Prognostic impact of chemoradiation-related lymphopenia in patients with gastric and gastroesophageal cancer

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Background: Limited data exists on how chemoradiation (CRT)-induced lymphopenia affects survival outcomes in patients with gastric and gastroesophageal junction (GEJ) cancer. We evaluated the association between severe lymphopenia and its association with survival in gastric and GEJ cancer patients treated with CRT. We hypothesized that severe lymphopenia would be a poor prognostic factor. Methods: We performed a retrospective analysis of 154 patients with stage 1-3 gastric or GEJ cancer who underwent CRT at our institution. Patients underwent photon-based radiation therapy (RT) with a median dose of 50.4 Gy (IQR 45.0-50.4 Gy) over 28 fractions and concurrent chemotherapy (CTX) with carboplatin/paclitaxel, 5-fluorouracil based regimen, or capecitabine. 49% received CTX prior to RT. 84% underwent surgical resection, 57% pre-CRT and 26% post-CRT. Absolute lymphocyte count (ALC) at baseline and at 2 months since initiating RT were analyzed. Severe lymphopenia, defined as Grade 3 or worse lymphopenia (ALC < 0.5 k/μl), was analyzed for any association with overall survival (OS). Results: Median time of follow up was 48 months. Median age was 65. 77% were male and 86% were Caucasian. ECOG PS was 0 or 1 in 90% and 2 in 10%. Tumor location was stomach in 38% and GEJ in 62%. Timing of CRT was preoperative among 68% and postoperative among 32%. The median ALC at baseline for the entire cohort was 1.6 k/ul (range 0.3-7.0 k/ul). At 2 months post-CRT, 49 (32%) patients had severe lymphopenia. Patients with severe lymphopenia post-CRT had a slightly lower baseline TLC compared to patients without severe lymphopenia (median TLC 1.4 k/ul vs. 1.6 k/ul; p = 0.005). There were no differences in disease and treatment characteristics between the two groups. On the multivariable Cox model, severe lymphopenia post-CRT was significantly associated with increased risk of death (HR = 3.99 [95% CI 1.55-10.28], p = 0.004). ECOG PS 2 (HR = 34.97 [95% CI 2.08-587.73], p = 0.014) and postoperative CRT (HR = 5.55 [95% CI 1.29-23.86], p = 0.021) also predicted worse OS. The 4-year OS among patients with severe lymphopenia was 41% vs. 61% among patients with vs. without severe lymphopenia (log-rank test p = 0.041). Conclusions: Severe lymphopenia significantly correlated with poorer OS in patients with gastric or GEJ cancer treated with CRT. CRT-induced lymphopenia may be an important prognostic factor for survival in this patient population. Closer observation in high-risk patients and treatment modifications may be potential approaches to mitigating CRT-induced lymphopenia.

Prognostic impact of chemoradiation-related lymphopenia in patients with locally advanced pancreatic cancer

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Background: Chemoradiation (CRT) induced lymphopenia is common and associated with poorer survival in multiple solid malignancies. The objective of this study was to evaluate the prognostic impact of lymphopenia in patients with nonmetastatic, unresectable pancreatic ductal adenocarcinoma (PDAC) treated by neoadjuvant FOLFIRINOX (5-fluorouracil [5FU]/leucovorin/irinotecan/oxaliplatin) followed by CRT. We hypothesized that severe lymphopenia would correlate with worse survival. Methods: The inclusion criteria for this single-institution retrospective study were: 1) biopsy-proven diagnosis of unresectable PDAC, 2) absence of distant metastasis, 3) receipt of neoadjuvant FOLFIRINOX followed by CRT, and 4) absolute lymphocyte count (ALC) available prior to and two months after initiating CRT. In general, CRT consisted of 5FU or capecitabine and RT with 58.8 Gy over 28 fractions. Lymphopenia was graded according to CTCAE v5.0. The primary variable of interest was lymphopenia at two months, dichotomized by ALC of < 0.5/μl (Grade 3 lymphopenia). The primary endpoint was overall survival (OS). Cox modeling and Kaplan-Meier methods were used to perform survival analyses. Results: A total of 138 patients were identified. Median follow-up for the entire cohort was 16 months. Median age was 65. Fifty-six percent were female, 86% were Caucasian, and 97% had ECOG ≤1. Median tumor size was 3.8 cm. Tumor location was pancreatic head in 63%, body in 22%, tail in 8%, and neck in 7%. Median baseline ALC for the entire cohort was 1.5 k/ul. Two months after initiating CRT, 106 (77%) had severe (Grade 3 or worse) lymphopenia. While there were no significant differences in baseline patient or disease characteristics, patients with severe lymphopenia received higher doses of RT with longer duration of treatment compared to those without severe lymphopenia. On multivariable Cox model, severe lymphopenia at two months was significantly associated with increased hazards of death (HR = 4.00 [95% CI 2.03-7.89], p < 0.001). Greater number of neoadjuvant FOLFIRINOX cycles received prior to CRT was associated with lower hazards of death (HR = 0.84 [95% CI 0.77-0.92], p < 0.001). The 12-month OS was 73% vs. 90% in the cohort with vs. without severe lymphopenia, respectively (log-rank p < 0.001). Conclusions: Treatment-related lymphopenia is common and severe lymphopenia may be a prognostic marker of poorer survival in locally advanced pancreatic cancer. Closer observation in high-risk patients and minimization of RT dose and duration are potential approaches to mitigating CRT-related lymphopenia. Our findings also suggest an important role of the host immunity in pancreatic cancer outcomes, supporting the ongoing efforts of immunotherapy trials in pancreatic cancer.

Circulating Tumor DNA Predicts Pathologic and Clinical Outcomes Following Neoadjuvant Chemoradiation and Surgery for Patients With Locally Advanced Rectal Cancer

PURPOSE

This study was designed to assess the ability of perioperative circulating tumor DNA (ctDNA) to predict surgical outcome and recurrence following neoadjuvant chemoradiation for locally advanced rectal cancer (LARC).

MATERIALS AND METHODS

Twenty-nine patients with newly diagnosed LARC treated between January 2014 and February 2018 were enrolled. Patients received long-course neoadjuvant chemoradiation prior to surgery. Plasma ctDNA was collected at baseline, preoperatively, and postoperatively. Next-generation sequencing was used to identify mutations in the primary tumor, and mutation-specific droplet digital polymerase chain reaction was used to assess mutation fraction in ctDNA.

RESULTS

The median age was 54 years. The overall margin-negative, node-negative resection rate was 73% and was significantly higher among patients with undetectable preoperative ctDNA (n = 17, 88%) versus patients with detectable preoperative ctDNA (n = 9, 44%; P = .028). Undetectable ctDNA was also associated with more favorable neoadjuvant rectal scores (univariate linear regression, P = .029). Recurrence-free survival (RFS) was calculated for the subset (n = 19) who both underwent surgery and had postoperative ctDNA available. At a median follow-up of 20 months, patients with detectable postoperative ctDNA experienced poorer RFS (hazard ratio, 11.56; P = .007). All patients (4 of 4) with detectable postoperative ctDNA recurred (positive predictive value = 100%), whereas only 2 of 15 patients with undetectable ctDNA recurred (negative predictive value = 87%).

CONCLUSION

Among patients treated with neoadjuvant chemoradiation for LARC, patients with undetectable preoperative ctDNA were more likely to have a favorable surgical outcome as measured by the rate of margin-negative, node-negative resections and neoadjuvant rectal score. Furthermore, we have confirmed prior reports indicating that detectable postoperative ctDNA is associated with worse RFS. Future prospective study is needed to assess the potential for ctDNA to assist with personalizing treatment for LARC.

Impact of Treatment Sequencing on Survival for Patients with Locally Advanced Gastric Cancer

BACKGROUND

Data are limited concerning the survival outcomes of locally advanced gastric cancer patients according to the multimodality therapy (MMT) administered.

METHODS

Single institution, retrospective analysis of 235 patients with locally advanced gastric cancer from 2001 to 2015. All patients met criteria for curative-intent surgery and chemotherapy ± radiation therapy. Treatment regimens were: (1) surgery first with adjuvant chemoradiation therapy (S + Adj); (2) perioperative chemotherapy + surgery (Periop); and (3) total neoadjuvant therapy followed by surgery (TNT + S).

RESULTS

One hundred twenty-eight (60.0%) patients received S + Adj, 69 (26.8%) Periop, and 38 (13.2%) TNT + S. Of the 235 patients, 222 (94.5%) received surgery. All intended therapy was received by 81.6% of TNT + S, 44.5% of S + Adj, and 42.0% of Periop patients. MMT was significantly more likely to be completed by TNT + S patients (HR 6.67, p < 0.001). At a median follow-up of 37 months, survival rates on an intention-to-treat basis with TNT + S, Periop, and S + Adj were 52.6%, 59.4%, and 45.3%, respectively. Regimen and completion of MMT significantly affected overall mortality risk. Compared with Periop, TNT + S had similar mortality risk (hazard ratio [HR] 1.28, p = 0.421), whereas S + Adj had increased mortality risk (HR 1.64, p = 0.027).

CONCLUSIONS

The choice of treatment sequencing has a major impact on completion rates of multimodal therapy in patients with locally advanced gastric cancer. Less than 50% of patients treated with upfront surgery or perioperative chemotherapy receive all intended therapies. TNT has higher intended therapy completion rates and comparable survival compared with perioperative therapy in our data. Further prospective investigations of TNT are warranted.

Intraoperative Radiation Mitigates the Effect of Microscopically Positive Tumor Margins on Survival Among Pancreatic Adenocarcinoma Patients Treated with Neoadjuvant FOLFIRINOX and Chemoradiation

BACKGROUND

Microscopically positive margins (R1) negatively impact survival in pancreatic ductal adenocarcinoma (PDAC). For patients with close/positive margins, intraoperative radiotherapy (IORT) can improve local control. The prognostic impact of an R1 resection in patients who receive total neoadjuvant therapy (TNT; FOLFIRINOX with chemoradiation) and IORT is unknown.

METHODS

Clinicopathologic data were retrospectively collected for borderline/locally advanced (BR/LA) PDAC patients who received TNT and underwent resection between 2011 and 2019. Disease-free (DFS) and overall survival (OS) measured from time of diagnosis were compared between groups.

RESULTS

Two hundred one patients received TNT and were resected, with a median DFS and OS of 24 months and 47 months, respectively. Eighty-eight patients (44%) received IORT; of these, 69 (78%) underwent an R0 and 19 (22%) an R1 resection. There was no significant difference in clinicopathologic factors between the IORT and no-IORT groups, except for resectability status (LA: IORT 69%, no-IORT 53%, p = 0.021) and surgeons' concern for a positive/close margin. R1 resection was associated with worse DFS and OS in the no-IORT population. However, among patients who received IORT, there was no difference in DFS (R0: 29 months, IQR 14-47 vs R1: 20 months, IQR 15-28; p = 0.114) or OS (R0: 48 months, IQR 25-not reached vs R1: 37 months, IQR 30-47; p = 0.307) between patients who underwent R0 vs R1 resection. In multivariate analysis, within the IORT group, R1 resection was not associated with DFS or OS.

CONCLUSION

IORT may mitigate the adverse effect of an R1 resection on DFS and OS in BR/LA PDAC patients receiving TNT.

Radiation Therapy for Rectal Cancer: Executive Summary of an ASTRO Clinical Practice Guideline

PURPOSE

This guideline reviews the evidence and provides recommendations for the indications and appropriate technique and dose of neoadjuvant radiation therapy (RT) in the treatment of localized rectal cancer.

METHODS

The American Society for Radiation Oncology convened a task force to address 4 key questions focused on the use of RT in preoperative management of operable rectal cancer. These questions included the indications for neoadjuvant RT, identification of appropriate neoadjuvant regimens, indications for consideration of a nonoperative or local excision approach after chemoradiation, and appropriate treatment volumes and techniques. Recommendations were based on a systematic literature review and created using a predefined consensus-building methodology and system for grading evidence quality and recommendation strength.

RESULTS

Neoadjuvant RT is recommended for patients with stage II-III rectal cancer, with either conventional fractionation with concurrent 5-FU or capecitabine or short-course RT. RT should be performed preoperatively rather than postoperatively. Omission of preoperative RT is conditionally recommended in selected patients with lower risk of locoregional recurrence. Addition of chemotherapy before or after chemoradiation or after short-course RT is conditionally recommended. Nonoperative management is conditionally recommended if a clinical complete response is achieved after neoadjuvant treatment in selected patients. Inclusion of the rectum and mesorectal, presacral, internal iliac, and obturator nodes in the clinical treatment volume is recommended. In addition, inclusion of external iliac nodes is conditionally recommended in patients with tumors invading an anterior organ or structure, and inclusion of inguinal and external iliac nodes is conditionally recommended in patients with tumors involving the anal canal.

CONCLUSIONS

Based on currently published data, the American Society for Radiation Oncology task force has proposed evidence-based recommendations regarding the use of RT for rectal cancer. Future studies will look to further personalize treatment recommendations to optimize treatment outcomes and quality of life.

Abstract PR-007: Single-nucleus and spatial transcriptomics of archival pancreatic ductal adenocarcinoma reveals multi-compartment reprogramming after neoadjuvant treatment

Molecular subtyping of pancreatic ductal adenocarcinoma (PDAC) remains in its nascent stages and does not currently inform clinical management or therapeutic development. Previously identified bulk expression subtypes in the untreated setting were influenced by contaminating stroma whereas single cell RNA-seq (scRNA-seq) of fresh tumors under-represented key cell types. Two consensus subtypes have arisen from these prior efforts: (1) classical-pancreatic, encompassing a spectrum of pancreatic lineage precursors, and (2) basal-like/squamous/quasi-mesenchymal, characterized by loss of endodermal identity and aberrations in chromatin modifiers. Basal-like tumors were associated with poorer responses to chemotherapy and worse survival in the metastatic setting but attempts to refine this binary classification have failed to further stratify patient survival. Recent clinical trials have supported the increasing adoption of neoadjuvant therapy to aggressively address the risk of micro-metastatic spread and to circumvent concerns of treatment tolerance in the postoperative setting. There is an urgent need to understand how preoperative treatment reprograms residual tumor cells to identify additional therapeutic vulnerabilities that can be exploited in combination with neoadjuvant CRT. Here, we developed a robust single-nucleus RNA-seq (snRNA-seq) technique for frozen archival PDAC specimens and used it to study both untreated tumors (n = 15) and those that received neoadjuvant CRT (n = 11). Gene expression programs learned across malignant cell and fibroblast profiles uncovered a clinically relevant molecular taxonomy with improved prognostic stratification (median survival: 11.2 months in highest risk group to 44.7 months in lowest risk group) compared to prior classifications. Moreover, in the neoadjuvant treatment context, there was lower expression of classical-like phenotypes in malignant cells in favor of basal-like phenotypes associated with TNF-NFkB and interferon signaling as well as the presence of novel acinar and neuroendocrine classical-like states, which may be more resilient to cytotoxic treatment. These results suggest that differentiated endodermal phenotypes are only prevalent enough to be detected under treatment selection pressure and when observed in treatment-naïve bulk studies, may reflect normal cell contamination. Spatially-resolved transcriptomics revealed an association between malignant cells expressing basal-like programs and higher immune infiltration with increased lymphocytic content, whereas those exhibiting classical-like programs were linked to sparser macrophage-predominant microniches, perhaps pointing to distinct therapeutic susceptibilities. Our refined molecular taxonomy and spatial resolution may help advance precision oncology in PDAC through informative stratification in clinical trials and insights into differential therapeutic targeting leveraging the immune system.

Citation Format: William L. Hwang, Karthik A. Jagadeesh, Jimmy A. Guo, Hannah I. Hoffman, Eugene Drokhlyansky, Nicholas Van Wittenberghe, Samouil Farhi, Denis Schapiro, Jason Reeves, Daniel R. Zollinger, George Eng, Jason M. Schenkel, William A. Freed-Pastor, Clifton Rodrigues, Domenic Abbondanza, Debora Ciprani, Jennifer Y. Wo, Theodore S. Hong, Andrew J. Aguirre, Orit Rozenblatt-Rosen, Mari Mino-Kenudson, Carlos Fernandez-del Castillo, Andrew S. Liss, Tyler E. Jacks, Aviv Regev. Single-nucleus and spatial transcriptomics of archival pancreatic ductal adenocarcinoma reveals multi-compartment reprogramming after neoadjuvant treatment [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr PR-007.

Chemoradiation-Related Lymphopenia and Its Association with Survival in Patients with Squamous Cell Carcinoma of the Anal Canal

BACKGROUND

Although treatment-related lymphopenia (TRL) is common and associated with poorer survival in multiple solid malignancies, few data exist for anal cancer. We evaluated TRL and its association with survival in patients with anal cancer treated with chemoradiation (CRT).

MATERIALS AND METHODS

A retrospective analysis of 140 patients with nonmetastatic anal squamous cell carcinoma (SCC) treated with definitive CRT was performed. Total lymphocyte counts (TLC) at baseline and monthly intervals up to 12 months after initiating CRT were analyzed. Multivariable Cox regression analysis was performed to evaluate the association between overall survival (OS) and TRL, dichotomized by grade (G)4 TRL (<0.2k/μL) 2 months after initiating CRT. Kaplan-Meier and log-rank tests were used to compare OS between patients with versus without G4 TRL.

RESULTS

Median time of follow-up was 55 months. Prior to CRT, 95% of patients had a normal TLC (>1k/μL). Two months after initiating CRT, there was a median of 71% reduction in TLC from baseline and 84% of patients had TRL: 11% G1, 31% G2, 34% G3, and 8% G4. On multivariable Cox model, G4 TRL at two months was associated with a 3.7-fold increased risk of death. On log-rank test, the 5-year OS rate was 32% in the cohort with G4 TRL versus 86% in the cohort without G4 TRL.

CONCLUSION

TRL is common and may be another prognostic marker of OS in anal cancer patients treated with CRT. The association between TRL and OS suggests an important role of the host immunity in anal cancer outcomes.

IMPLICATIONS FOR PRACTICE

This is the first detailed report demonstrating that standard chemoradiation (CRT) commonly results in treatment-related lymphopenia (TRL), which may be associated with a poorer overall survival (OS) in patients with anal squamous cell carcinoma. The association between TRL and worse OS observed in this study supports the importance of host immunity in survival among patients with anal cancer. These findings encourage larger, prospective studies to further investigate TRL, its predictors, and its relationship with survival outcomes. Furthermore, the results of this study support ongoing efforts of clinical trials to investigate the potential role of immunotherapy in anal cancer.

Patterns of Failure and the Need for Biliary Intervention in Resected Biliary Tract Cancers After Chemoradiation

BACKGROUND

This study assessed patterns of failure and rates of subsequent biliary intervention among patients with resected biliary tract cancers (BTCs) including gallbladder carcinoma (GBC) and extra- and intrahepatic cholangiocarcinoma (eCCA and iCCA) treated with adjuvant chemoradiation therapy (CRT).

METHODS

In this single-institution retrospective analysis of 80 patients who had GBC (n = 29), eCCA (n = 43), or iCCA (n = 8) treated with curative-intent resection and adjuvant CRT from 2007 to 2017, the median radiation dose was 50.4 Gy (range 36-65 Gy) with concurrent 5-fluorouracil (5-FU) chemotherapy. All but two of the patients received adjuvant chemotherapy. The 2-year locoregional failure (LRF), 2-year recurrence-free survival (RFS), and 2-year overall survival (OS), and univariate predictors of LRF, RFS, and OS were calculated for the entire cohort and for a subgroup excluding patients with iCCA (n = 72). The predictors of biliary interventions also were assessed.

RESULTS

Of the 80 patients (median follow-up period, 30.5 months; median OS, 33.9 months), 54.4% had American Joint Committee on Cancer (AJCC) stage 1 or 2 disease, 57.1% were lymph node-positive, and 66.3% underwent margin-negative resection. For the entire cohort, 2-year LRF was 23.8%, 2-year RFS was  43.7%, and 2-year OS was 62.1%.  When patients with iCCA were excluded, the 2-year LRF was 22.6%, the 2-year RFS was 43.9%, and the 2-year OS was 59.2%. In the overall and subgroup univariate analyses, lymph node positivity was associated with greater LRF, whereas resection margin was not. Biliary intervention was required for 12 (63.2%) of the 19 patients with LRF versus 11 (18%) of the 61 patients without LRF (P < 0.001). Of the 12 patients with LRF who required biliary intervention, 4 died of biliary complications.

CONCLUSIONS

The LRF rates remained significant despite adjuvant CRT. Lymph node positivity may be associated with increased risk of LRF. Positive margins were not associated with greater LRF, suggesting that CRT may mitigate LRF risk for this group. An association between LRF and higher rates of subsequent biliary interventions was observed, which may yield significant morbidity. Novel strategies to decrease the rates of LRF should be considered.

Pancreatic ductal adenocarcinoma: tumour regression grading following neoadjuvant FOLFIRINOX and radiation

AIMS

In the adjuvant setting, when compared to gemcitabine, patients with pancreatic ductal adenocarcinoma (PDAC) treated with FOLFIRINOX (Folinic Acid, Fluorouracil, Irinotecan, and Oxaliplatin) show superior survival. In this study, we quantitatively assess the pathological tumour response to chemoradiation in pancreatectomy specimens and reassess guidelines for tumour regression grading.

METHODS AND RESULTS

We evaluated 92 patients with borderline resectable/locally advanced PDAC following pancreatectomy and neoadjuvant treatment with FOLFIRINOX and radiation. Demographic data, CAP tumour regression grade (TRG) and overall survival (OS) were recorded. A quantitative analysis of residual tumour was performed on the slide with the highest tumour burden to derive a tumour-to-tumour bed ratio. On univariate analysis, only lymph node status (P = 0.043) and CAP TRG (P = 0.038) correlated with OS. Sixteen per cent of patients showed a complete pathological response. The optimal tumour-to-tumour bed ratio cut-point was 11.6%, and on a multivariate model was the only pathological parameter that correlated with OS (P = 0.016) (hazard ratio = 2.27).

CONCLUSIONS

The high proportion of patients with PDAC showing complete and near-complete pathological responses supports the use of FOLFIRINOX and radiation in the neoadjuvant setting. Several traditional pathology parameters fail to predict OS in patients treated with chemoradiation, while a quantitative tumour-to-tumour bed ratio is a powerful predictor of OS. The data support a two-tiered approach to TRG based on tumour-to-tumour bed ratio, and quantitative analysis merits further consideration.

Refusal of surgery for colon cancer: Sociodemographic disparities and survival implications among US patients with resectable disease

BACKGROUND

We aimed to identify factors associated with refusal of surgery among patients with colon cancer.

METHODS

This 2004-2016 NCDB retrospective study identified AJCC stage I-III colon cancer patients who were recommended surgery. Multivariable logistic regression defined adjusted odds ratios of refusing treatment, with sociodemographic and clinical covariates. Treatment propensity-adjusted Cox proportional hazard ratios defined differential survival stratified by clinical stage, controlling for potential confounders.

RESULTS

Of 170,594 patients recommended surgery, 1116 refused. Increased rates of surgery refusal were associated with older age, African American race, CDCC>3, and female sex. Decreased rates of surgery refusal were associated with higher income and private insurance. Stratifying by stage, refusal rates among African Americans remained disparately high. Refusal of surgery was associated with worse overall survival.

CONCLUSIONS

Disparate rates of refusal of surgery for resectable colon cancer by race and other sociodemographic factors highlight potential treatment adherence reinforcement beneficiaries, necessitating further study of shared decision-making.

Impact of adjuvant therapy in patients with invasive intraductal papillary mucinous neoplasms of the pancreas

BACKGROUND

There is limited data on the efficacy of adjuvant therapy (AT) in patients with invasive intraductal papillary mucinous neoplasms of the pancreas (IPMN). This single center retrospective cohort study aims to assess the impact of AT on survival in these patients.

METHODS

Patients undergoing surgery for invasive IPMN between 1993 and 2018 were included in the study. We compared the clinicopathologic features and evaluated overall survival (OS) using multivariate Cox regression adjusting for adjuvant therapy, age, T and N stage, perineural and lymphovascular invasion. We also assessed survival differences between surgery alone and AT in node negative (N0) and node positive (N+) subgroups.

RESULTS

103 patients were included in the study; 69 underwent surgery alone while 34 also received AT. Patients in the AT group were significantly younger, presented at higher T and N stages and had more perineural and lymphovascular invasion. Median OS in the surgery alone group was 134 months and 65 months in the AT group, p = 0.052. On multivariate analysis, AT was not associated with improved OS; hazard ratio (HR) = 1.03 (0.52-2.05). In N0 patients, compared to surgery alone, AT was associated with a worse median OS (65 vs 167 months, p = 0.03), whereas in N+ patients there was a non-significant improvement (50.5 vs 20.4 months, p = 0.315).

CONCLUSION

AT did not improve survival in the overall cohort even after multivariate analysis. N0 patients have excellent survival, and AT should probably be avoided in them, whereas it may be considered in patients with N+ disease.

Dosimetric Analysis and Normal-Tissue Complication Probability Modeling of Child-Pugh Score and Albumin-Bilirubin Grade Increase After Hepatic Irradiation

PURPOSE

This study aimed to develop robust normal-tissue complication probability (NTCP) models for patients with hepatocellular carcinoma treated with radiation therapy (RT) using Child-Pugh (CP) score and albumin-bilirubin (ALBI) grade increase as endpoints for hepatic toxicity.

METHODS AND MATERIALS

Data from 108 patients with hepatocellular carcinoma treated with RT between 2008 and 2017 were evaluated, of which 47 patients (44%) were treated with proton RT. Of these patients, 29 received stereotactic body RT and 79 moderately hypofractionated RT to median physical tumor doses of 43 Gy in 5 fractions and 59 Gy in 15 fractions, respectively. A generalized Lyman-Kutcher-Berman (LKB) model was used to model the NTCP using 2 clinical endpoints, both evaluated at 3 months after RT: CP score increase of ≥2 and ALBI grade increase of ≥1 from the pre-RT baseline. Confidence intervals on LKB fit parameters were determined using bootstrap resampling.

RESULTS

Compared with previous NTCP models, this study found a stronger correlation between normal liver volume receiving low doses of radiation (5-10 Gy) and a CP score or ALBI grade increase. A CP score increase exhibited a stronger correlation to normal liver volumes irradiated than an ALBI grade increase. LKB models for CP increase found values for the volume-effect parameter of a = 0.06 for all patients, and a = 0.02/0.09 when fit to photon/proton patients separately. Subset analyses for patients with superior initial liver functions showed consistent dose-volume effects (a = 0.1) and consistent dose-response relationships.

CONCLUSIONS

This study presents an update of liver NTCP models in the era of modern RT techniques using relevant endpoints of hepatic toxicity, CP score and ALBI grade increase. The results show a stronger influence of low-dose bath on hepatic toxicity than those found in previous studies, indicating that RT techniques that minimize the low-dose bath may be beneficial for patients.

Serial ctDNA Monitoring to Predict Response to Systemic Therapy in Metastatic Gastrointestinal Cancers

PURPOSE

ctDNA offers a promising, noninvasive approach to monitor therapeutic efficacy in real-time. We explored whether the quantitative percent change in ctDNA early after therapy initiation can predict treatment response and progression-free survival (PFS) in patients with metastatic gastrointestinal cancer.

EXPERIMENTAL DESIGN

A total of 138 patients with metastatic gastrointestinal cancers and tumor profiling by next-generation sequencing had serial blood draws pretreatment and at scheduled intervals during therapy. ctDNA was assessed using individualized droplet digital PCR measuring the mutant allele fraction in plasma of mutations identified in tumor biopsies. ctDNA changes were correlated with tumor markers and radiographic response.

RESULTS

A total of 138 patients enrolled. A total of 101 patients were evaluable for ctDNA and 68 for tumor markers at 4 weeks. Percent change of ctDNA by 4 weeks predicted partial response (PR, P < 0.0001) and clinical benefit [CB: PR and stable disease (SD), P < 0.0001]. ctDNA decreased by 98% (median) and >30% for all PR patients. ctDNA change at 8 weeks, but not 2 weeks, also predicted CB (P < 0.0001). Four-week change in tumor markers also predicted response (P = 0.0026) and CB (P = 0.022). However, at a clinically relevant specificity threshold of 90%, 4-week ctDNA change more effectively predicted CB versus tumor markers, with a sensitivity of 60% versus 24%, respectively (P = 0.0109). Patients whose 4-week ctDNA decreased beyond this threshold (≥30% decrease) had a median PFS of 175 days versus 59.5 days (HR, 3.29; 95% CI, 1.55-7.00; P < 0.0001).

CONCLUSIONS

Serial ctDNA monitoring may provide early indication of response to systemic therapy in patients with metastatic gastrointestinal cancer prior to radiographic assessments and may outperform standard tumor markers, warranting further evaluation.

Total Neoadjuvant Therapy With FOLFIRINOX in Combination With Losartan Followed by Chemoradiotherapy for Locally Advanced Pancreatic Cancer: A Phase 2 Clinical Trial

Importance

Patients with locally advanced pancreatic cancer have historically poor outcomes. Evaluation of a total neoadjuvant approach is warranted.

Objective

To evaluate the margin-negative (R0) resection rate of neoadjuvant FOLFIRINOX (fluorouracil, leucovorin, oxaliplatin, and irinotecan) and losartan followed by chemoradiotherapy for locally advanced pancreatic cancer.

Design, Setting, and Participants

A single-arm phase 2 clinical trial was conducted at a large academic hospital from August 22, 2013, to May 22, 2018, among 49 patients with previously untreated locally advanced unresectable pancreatic cancer as determined by multidisciplinary review. Patients had Eastern Cooperative Oncology Group performance status 0 or 1 and adequate hematologic, renal, and hepatic function. Median follow-up for the analysis was 17.1 months (range, 5.0-53.7) among 27 patients still alive at study completion.

Interventions

Patients received FOLFIRINOX and losartan for 8 cycles. Patients with radiographically resectable tumor after chemotherapy received short-course chemoradiotherapy (5 GyE × 5 with protons) with capecitabine. Patients with persistent vascular involvement received long-course chemoradiotherapy (50.4 Gy with a vascular boost to 58.8 Gy) with fluorouracil or capecitabine.

Main Outcomes and Measures

R0 resection rate.

Results

Of the 49 patients (26 women and 23 men; median age 63 years [range, 42-78 years]), 39 completed 8 cycles of FOLFIRINOX and losartan; 10 patients had fewer than 8 cycles due to progression (5 patients), losartan intolerance (3 patients), and toxicity (2 patients). Seven patients (16%) had short-course chemoradiotherapy while 38 (84%) had long-course chemoradiotherapy. Forty-two (86%) patients underwent attempted surgery, with R0 resection achieved in 34 of 49 patients (69%; 95% CI, 55%-82%). Overall median progression-free survival was 17.5 months (95% CI: 13.9-22.7) and median overall survival was 31.4 months (95% CI, 18.1-38.5). Among patients who underwent resection, median progression-free survival was 21.3 months (95% CI, 16.6-28.2), and median overall survival was 33.0 months (95% CI, 31.4 to not reached).

Conclusions and Relevance

Total neoadjuvant therapy with FOLFIRINOX, losartan, and chemoradiotherapy provides downstaging of locally advanced pancreatic ductal adenocarcinoma and is associated with an R0 resection rate of 61%.

Trial Registration

ClinicalTrials.gov identifier: NCT01821729.

Proton beam radiotherapy for anal and rectal cancers

Gastrointestinal cancers are bordered by radiosensitive visceral organs, resulting in a narrow therapeutic window. The search for more efficacious and tolerable therapies raises the possibility that proton beam therapy's (PBT) physical and dosimetric differences from conventional therapy may be better suited to treat both primary and recurrent disease, which carries its own unique challenges. Currently, the maximal efficacy of radiation plans for primary and recurrent anorectal cancer is constrained by delivery techniques and modalities which must consider feasibility challenges and toxicity secondary to exposure of organs at risk (OARs). Studies using volumetric modulated arc therapy (VMAT) and intensity modulated radiation therapy (IMRT) demonstrate that more precise dose delivery to target volumes improves local control rates and reduces complications. By reducing the low-to-moderate radiation dose-bath to bone marrow, small and large bowel, and skin, PBT may offer an improved side-effect profile. The potential to reduce toxicity, increase patient compliance, minimize treatment breaks, and enable dose escalation or hypofractionation is appealing. In cases where prognosis is favorable, PBT may mitigate long-term morbidity such as secondary malignancies, femoral fractures, and small bowel obstruction.

Predictors of Resectability and Survival in Patients With Borderline and Locally Advanced Pancreatic Cancer who Underwent Neoadjuvant Treatment With FOLFIRINOX

OBJECTIVE

The aim of this study was to determine (1) whether preoperative factors can predict resectability of borderline resectable (BR) and locally advanced (LA) pancreatic ductal adenocarcinoma (PDAC) after neoadjuvant FOLFIRINOX, (2) which patients might benefit from adjuvant therapy, and (3) survival differences between resected BR/LA patients who received neoadjuvant FOLFIRINOX and upfront resected patients.

BACKGROUND

Patients with BR/LA PDAC are often treated with FOLFIRINOX to obtain a margin-negative resection, yet selection of patients for resection remains challenging.

METHODS

Clinicopathologic data of PDAC patients surgically explored between 04/2011-11/2016 in a single institution were retrospectively collected.

RESULTS

Following neoadjuvant FOLFIRINOX, 141 patients were surgically explored (BR: 49%, LA: 51%) and 110 (78%) were resected. Resected patients had lower preoperative CA 19-9 levels (21 vs 40 U/mL, P = 0.03) and smaller tumors on preoperative computed tomography (CT) scan (2.3 vs 3.0 cm, P = 0.03), but no predictors of resectability were identified. Median overall survival (OS) was 34.2 months from diagnosis for all FOLFIRINOX patients and 37.7 months for resected patients. Among resected patients, preoperative CA 19-9 >100 U/mL and >8 months between diagnosis and surgery predicted a shorter postoperative disease-free survival (DFS); Charlson comorbidity index >1, preoperative CA 19-9 >100 U/mL and tumor size (>3.0 cm on CT or >2.5 cm on pathology) predicted decreased OS. DFS and OS were significantly better for BR/LA PDAC patients treated with neoadjuvant FOLFIRINOX compared with upfront resected patients (DFS: 29.1 vs 13.7, P < 0.001; OS: 37.7 vs 25.1 months from diagnosis, P = 0.01).

CONCLUSION

BR/LA PDAC patients with no progression on neoadjuvant FOLFIRINOX should be offered surgical exploration. Except size, traditional pathological parameters fail to predict survival among resected FOLFIRINOX patients. Resected FOLFIRINOX patients have survival that appears to be superior than that of resectable patients who go directly to surgery.

Hypofractionated Radiation Therapy for Unresectable/Locally Recurrent Intrahepatic Cholangiocarcinoma

OBJECTIVE

The aim of this study was to evaluate outcomes for patients with unresectable intrahepatic cholangiocarcinoma (ICC) treated with hypofractionated proton or photon radiation therapy (HF-RT).

METHODS

We retrospectively identified 66 patients with ICC who were treated with HF-RT from 2008 to 2018. Median age at RT was 76 years (range 30-92), including 27 patients (41%) aged ≥ 80 years. Median RT dose was 58.05 Gy (range 37.5-67.5), all delivered in 15 daily fractions. Thirty-two patients received proton RT and 34 patients received photon RT.

RESULTS

Median follow-up times from diagnosis and RT start were 21 months and 14 months, respectively. In total, five patients (7.6%) developed local failure. The 2-year outcomes were 84% local control (LC) and 58% OS. Among the 51 patients treated with definitive intent, the 2-year LC rate was 93% and the OS rate was 62%. On multivariate analysis for LC, older age was associated with a lower risk of local failure [hazard ratio (HR) 0.91; p = 0.02], while prior surgery (HR 16.5; p = 0.04) and macrovascular invasion (HR 123.93; p = 0.02) were independently associated with an increased risk of local failure. On multivariate analysis for OS, female sex (HR 0.33; p = 0.001) and prior chemotherapy (HR 0.38; p = 0.003) remained significantly associated with OS. On multivariate analysis for OS, compared with photon RT, there was a trend towards improved survival with proton RT (HR 0.50; p = 0.05). The rate of overall grade 3 + toxicity was 11%. One patient developed radiation-induced liver disease and was treated with corticosteroids.

CONCLUSIONS

HF-RT yields high rates of local control and is an effective modality to optimize biliary control for unresectable/locally recurrent ICC.

Author Correction: Liquid versus tissue biopsy for detecting acquired resistance and tumor heterogeneity in gastrointestinal cancers

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Management implications of fluorodeoxyglucose positron emission tomography/magnetic resonance in untreated intrahepatic cholangiocarcinoma

PURPOSE

Intrahepatic cholangiocarcinoma (ICC) is associated with a poor prognosis with surgical resection offering the best chance for long-term survival and potential cure. However, in up to 36% of patients who undergo surgery, more extensive disease is found at time of operation requiring cancellation of surgery. PET/MR is a novel hybrid technology that might improve local and whole-body staging in ICC patients, potentially influencing clinical management. This study was aimed to investigate the possible management implications of PET/MR, relative to conventional imaging, in patients affected by untreated intrahepatic cholangiocarcinoma.

METHODS

Retrospective review of the clinicopathologic features of 37 patients with iCCC, who underwent PET/MR between September 2015 and August 2018, was performed to investigate the management implications that PET/MR had exerted on the affected patients, relative to conventional imaging.

RESULTS

Of the 37 patients enrolled, median age 63.5 years, 20 (54%) were female. The same day PET/CT was performed in 26 patients. All patients were iCCC-treatment-naïve. Conventional imaging obtained as part of routine clinical care demonstrated early-stage resectable disease for 15 patients and advanced stage disease beyond the scope of surgical resection for 22. PET/MR modified the clinical management of 11/37 (29.7%) patients: for 5 patients (13.5%), the operation was cancelled due to identification of additional disease, while 4 "inoperable" patients (10.8%) underwent an operation. An additional 2 patients (5.4%) had a significant change in their operative plan based on PET/MR.

CONCLUSIONS

When compared with standard imaging, PET/MR significantly influenced the treatment plan in 29.7% of patients with iCCC.

TRIAL REGISTRATION

2018P001334.

Total Neoadjuvant Therapy With FOLFIRINOX Followed by Individualized Chemoradiotherapy for Borderline Resectable Pancreatic Adenocarcinoma: A Phase 2 Clinical Trial

Importance

Patients with borderline-resectable pancreatic ductal adenocarcinoma have historically poor outcomes with surgery followed by adjuvant chemotherapy. Evaluation of a total neoadjuvant approach with highly active therapy is warranted.

Objective

To evaluate the margin-negative (R0) resection rate in borderline-resectable pancreatic ductal adenocarcinoma after neoadjuvant FOLFIRINOX (fluorouracil, irinotecan, and oxaliplatin) therapy and individualized chemoradiotherapy.

Design, Setting, and Participants

A single-arm, phase 2 clinical trial was conducted at a large academic hospital with expertise in pancreatic surgery from August 3, 2012, through August 31, 2016, among 48 patients with newly diagnosed, previously untreated, localized pancreatic cancer determined to be borderline resectable by multidisciplinary review, who had Eastern Cooperative Oncology Group performance status 0 or 1 and adequate hematologic, renal, and hepatic function. Median follow-up for the analysis was 18.0 months among the 30 patients still alive at study completion.

Interventions

Patients received FOLFIRINOX for 8 cycles. Upon restaging, patients with resolution of vascular involvement received short-course chemoradiotherapy (5 Gy × 5 with protons) with capecitabine. Patients with persistent vascular involvement received long-course chemoradiotherapy with fluorouracil or capecitabine.

Main Outcomes and Measures

The primary outcome was R0 resection rate; secondary outcomes were median progression-free survival (PFS) and median overall survival (OS).

Results

Of the 48 eligible patients, 27 were men and 21 were women, with a median age of 62 years (range, 46-74 years). Of the 43 patients who planned to receive 8 preoperative cycles of chemotherapy, 34 (79%) were able to complete all cycles. Twenty-seven patients (56%) had short-course chemoradiotherapy, while 17 patients (35%) had long-course chemoradiotherapy. R0 resection was achieved in 31 of the 48 eligible patients (65%; 95% CI, 49%-78%). Among the 32 patients who underwent resection, the R0 resection rate was 97% (n = 31). Median PFS among all eligible patients was 14.7 months (95% CI, 10.5 to not reached), with 2-year PFS of 43%; median OS was 37.7 months (95% CI, 19.4 to not reached), with 2-year OS of 56%. Among patients who underwent resection, median PFS was 48.6 months (95% CI, 14.4 to not reached) and median OS has not been reached, with a 2-year PFS of 55% and a 2-year OS of 72%.

Conclusions and Relevance

Preoperative FOLFIRINOX followed by individualized chemoradiotherapy in borderline resectable pancreatic cancer results in high rates of R0 resection and prolonged median PFS and median OS, supporting ongoing phase 3 trials.

Trial Registration

ClinicalTrials.gov Identifier: NCT01591733.

Integrative Molecular Characterization of Resistance to Neoadjuvant Chemoradiation in Rectal Cancer

PURPOSE

Molecular properties associated with complete response or acquired resistance to concurrent chemotherapy and radiotherapy (CRT) are incompletely characterized.Experimental Design: We performed integrated whole-exome/transcriptome sequencing and immune infiltrate analysis on rectal adenocarcinoma tumors prior to neoadjuvant CRT (pre-CRT) and at time of resection (post-CRT) in 17 patients [8 complete/partial responders, 9 nonresponders (NR)].

RESULTS

CRT was not associated with increased tumor mutational burden or neoantigen load and did not alter the distribution of established somatic tumor mutations in rectal cancer. Concurrent KRAS/TP53 mutations (KP) associated with NR tumors and were enriched for an epithelial-mesenchymal transition transcriptional program. Furthermore, NR was associated with reduced CD4/CD8 T-cell infiltrates and a post-CRT M2 macrophage phenotype. Absence of any local tumor recurrences, KP/NR status predicted worse progression-free survival, suggesting that local immune escape during or after CRT with specific genomic features contributes to distant progression.

CONCLUSIONS

Overall, while CRT did not impact genomic profiles, CRT impacted the tumor immune microenvironment, particularly in resistant cases.

Clinical impact of PET/MR in treated colorectal cancer patients

PURPOSE

The primary aim of the present study was to evaluate if PET/MR induced management changes versus standard of care imaging (SCI) in treated colorectal cancer patients. The secondary aim was to assess the staging performance of PET/MR and of SCI versus the final oncologic stage.

METHODS

Treated CRC patients who underwent PET/MR with ¹⁸F-FDG and SCI between January 2016 and October 2018 were enrolled in this retrospective study. Their medical records were evaluated to ascertain if PET/MR had impacted on their clinical management versus SCI. The final oncologic stage, as reported in the electronic medical record, was considered the true stage of disease.

RESULTS

A total of 39 patients who underwent 42 PET/MR studies were included, mean age 56.7 years (range 39-75 years), 26 males, and 13 females. PET/MR changed clinical management 15/42 times (35.7%, standard error ± 7.4%); these 15 changes in management were due to upstaging in 9/42 (21.5%) and downstaging in 6/42 (14.2%). The differences in management prompted by SCI versus PET/MR were statistically significant, and PET/MR outperformed SCI (P value < 0.001; odds ratio = 2.8). In relation to the secondary outcome, PET/MR outperformed the SCI in accuracy of oncologic staging (P value = 0.016; odds ratio = 4.6).

CONCLUSIONS

PET/MR is a promising imaging tool in the evaluation of treated CRC and might change the management in these patients. However, multicenter prospective studies with larger patient samples are required in order to confirm these preliminary results.

Pencil Beam Scanning Proton Beam Chemoradiation Therapy With 5-Fluorouracil and Mitomycin-C for Definitive Treatment of Carcinoma of the Anal Canal: A Multi-institutional Pilot Feasibility Study

PURPOSE

Definitive chemoradiation with concurrent 5-fluorouracil (5-FU)/mitomycin C (MMC) is an effective treatment for localized anal cancer, but it is associated with significant acute long-term treatment-related toxicity. Pencil beam scanning proton beam (PBS-PT) radiation therapy may potentially reduce this toxicity. This is a multi-institutional pilot study evaluating the feasibility of definitive concurrent chemoradiation with PBS-PT in combination with 5-FU and MMC for carcinoma of the anal canal.

METHODS AND MATERIALS

Patients were enrolled on a National Cancer Institute-sponsored, prospective, multi-institutional, single-arm pilot study (NCT01858025). Key eligibility criteria included Eastern Cooperative Oncology Group 0 to 2, age ≥18 years, histologically confirmed invasive squamous cell carcinoma of the anal canal, and clinically staged T1-4, N0-3 disease. Patients were treated with PBS-PT per Radiation Therapy Oncology Group 0529 dose schema and concurrent 5-FU/MMC on day 1 and 29. The primary objective of this study was to determine feasibility of PBS-PT with concurrent 5-FU/MMC, defined as grade 3+ dermatologic toxicity less than 48% (reported grade 3+ dermatologic toxicity from Radiation Therapy Oncology Group 98-11). Secondary objectives were to determine the rates of overall grade 3+ toxicities, clinical complete response rate, and disease outcomes.

RESULTS

Between February 2014 and April 2017, we enrolled 25 patients into our study, all of whom were analyzed. Twenty-three patients (92%) completed treatment per protocol, and 2 patients died on treatment. Median time to completion of treatment was 42 days (range, 38-49). The grade 3+ radiation dermatitis rate was 24%. Median follow-up is 27 months (range, 21-50) among the 21 patients still alive. The overall rate of clinical complete response was 88%. The 2-year local failure, colostomy-free survival, progression-free survival, and overall survival are 12%, 72%, 80%, and 84%, respectively.

CONCLUSIONS

In our prospective, multi-institutional pilot study of PBS-PT with concurrent 5-FU/MMC, PBS-PT was found to be feasible. A phase 2 study of proton beam radiation therapy is currently underway.

Tolerability and Long-term Outcomes of Dose-Painted Neoadjuvant Chemoradiation to Regions of Vessel Involvement in Borderline or Locally Advanced Pancreatic Cancer

PURPOSE

We reviewed our experience involving patients with borderline resectable or locally advanced pancreatic cancer, treated with the dose-painted (DP) boost technique to regions of vessel involvement which preclude upfront surgical resection. We evaluated patient outcomes with respect to tolerability and treatment outcomes.

MATERIALS AND METHODS

We retrospectively reviewed 99 patients with borderline resectable (n=25) or locally advanced pancreatic cancer (n=74) treated with DP-neoadjuvant chemoradiation from 2010 to 2015. Tumor and regional lymph nodes were prescribed 50.4 Gy and the region around the involved blood vessel was boosted to 58.8 Gy in 28 fractions. The primary outcome was acute toxicity and late duodenal toxicity. Secondary outcomes included conversion to surgical resectability, local failure, disease-free survival, and overall survival (OS). Cox proportional hazards models were performed to evaluate for predictors of survival.

RESULTS

All but 1 patient completed chemoradiation. The rates of grade 2+ and 3+ nausea were 40% and 12%, respectively. With regards to late toxicity, 5 patients developed potential RT-related grade 3+ duodenal complications including duodenal ulceration/bleeding (n=3) and duodenal stricture (n=2). With a median follow-up of 15 months, the median OS was 18.1 months. Among 99 patients in our study, 37 patients underwent surgical resection. For patients who underwent surgical resection (n=37), the median OS was 30.9 months. On multivariate analysis, only normalization of CA 19-9 post-RT was associated with improved OS.

CONCLUSIONS

We found that DP-neoadjuvant chemoradiation to regions of vessel involvement is both feasible and well tolerated. In addition, we demonstrated that over one third of patients with initially deemed unresectable disease were able to undergo surgical resection after receiving neoadjuvant therapy including DP-chemoradiation.

Cost-effectiveness of Short-Course Radiation Therapy vs Long-Course Chemoradiation for Locally Advanced Rectal Cancer

IMPORTANCE

Although both short-course radiotherapy and long-course chemoradiotherapy have been practiced in parallel for more than 15 years, no cost-effectiveness analysis comparing these 2 approaches in patients with locally advanced rectal cancer has been published.

OBJECTIVE

To analyze the cost-effectiveness of short-course radiotherapy vs long-course chemoradiotherapy for the treatment of patients with locally advanced rectal cancer.

DESIGN, SETTING, AND PARTICIPANTS

This economic evaluation used a cost-effectiveness model simulating 10-year outcomes for 1 million hypothetical patients aged 65 years with locally advanced rectal cancer treated with either short-course radiotherapy or long-course chemoradiotherapy, followed by surgery and chemotherapy. Utilities and probabilities from the literature and costs from the Healthcare Bluebook and Medicare fee schedules were used to determine incremental cost-effectiveness ratios. It was assumed that long-course chemoradiotherapy would result in higher rates of low anterior resection (LAR). To model preference-sensitive care, a 2-way sensitivity analysis was conducted in which the utilities of the no-evidence-of-disease (NED) states with LAR and abdominoperineal resection (APR) were simultaneously varied. The analysis was repeated for patients with distal rectal tumors. Analysis was conducted from January to October 2018.

EXPOSURES

Short-course radiotherapy and long-course chemoradiotherapy.

MAIN OUTCOMES AND MEASURES

Incremental cost-effectiveness ratios.

RESULTS

Short-course radiotherapy was the cost-effective strategy compared with long-course chemoradiotherapy (incremental cost-effectiveness ratio, $133 495 per quality-adjusted life-year). Two-way sensitivity analysis revealed that the cost-effective approach for a given patient depended on the utilities for the NED-LAR and NED-APR states. Assuming that a greater proportion of patients with locally advanced distal tumors undergoing long-course chemoradiotherapy (39%) would proceed to LAR compared with those treated with short-course radiotherapy (19%), long-course chemoradiotherapy was the cost-effective approach (incremental cost-effectiveness ratio, $61 123 per quality-adjusted life-year).

CONCLUSIONS AND RELEVANCE

Short-course radiotherapy was the cost-effective strategy compared with long-course chemoradiotherapy for patients with locally advanced rectal cancer. The cost-effectiveness of short-course radiotherapy vs long-course chemoradiotherapy was sensitive to the utilities of the NED-LAR and NED-APR health states, highlighting the importance of care that is sensitive to patient preference. Long-course chemoradiotherapy was the cost-effective approach for patients with distal tumors.

High IDO1 Expression Is Associated with Poor Outcome in Patients with Anal Cancer Treated with Definitive Chemoradiotherapy

Despite increased incidence of anal squamous cell carcinoma (ASCC), treatment recommendations have remained unchanged for the past 35 years. This article profiles the tumor microenvironment of patients with localized ASCC, examining CD8, PD‐1, PD‐L1, IDO1 and HLA class I expression and, specifically, characterizes expression of IDO1 in the context of several key components of the immune microenvironment.

Background.

This study characterizes the tumor‐immune microenvironment in pretreatment, localized anal squamous cell carcinoma (ASCC), including two markers that have not previously been studied in ASCC: indoleamine 2,3 dioxygenase 1 (IDO1) and human leukocyte antigen (HLA) class I.

Materials and Methods.

Retrospective review identified 63 patients with ASCC receiving definitive chemoradiation between 2005 and 2016 with pretreatment tissue available. Immunohistochemistry was used to quantify cluster of differentiation 8 (CD8), programmed cell death protein 1, programmed death‐ligand 1, HLA class I, and IDO1. Cox proportional hazards models evaluated associations between outcomes and immune markers, controlling for clinical characteristics.

Results.

With a median follow‐up of 35 months, 3‐year overall survival was 78%. The only marker found to have a robust association with outcome was tumor IDO1. In general, the percentage of tumor cells expressing IDO1 was low (median 1%, interquartile range 0%–20%); however, patients with >50% of tumor cells expressing IDO1 had significantly worse overall survival (hazard ratio [HR] 4.7, p = .007) as well as higher local recurrence (HR 8.6, p = .0005) and distant metastasis (HR 12.7, p = .0002). Tumors with >50% IDO1 were also more likely to have the lowest quartile of CD8 infiltrate (<40 per high‐power field, p = .024).

Conclusion.

ASCC has a diverse immune milieu. Although patients generally do well with standard therapy, IDO1 may serve as a prognostic indicator of poor outcome and could help identify a patient population that might benefit from IDO‐targeted therapies.

Implications for Practice.

After definitive chemoradiation, patients with locally advanced anal cancer may experience significant treatment morbidity and high risk of recurrence. The goal of the current study is to identify novel prognostic factors in the tumor‐immune microenvironment that predict for poor outcomes after definitive chemoradiation. This study characterizes the tumor‐immune microenvironment in pre‐treatment, localized anal squamous cell carcinoma (ASCC), including two markers which have not previously been studied in ASCC: indoleamine 2,3 dioxygenase 1 (IDO1) and HLA class I. With a median follow‐up of 3 years, this study demonstrated that high IDO1 expression is correlated with significantly worse 3‐year overall survival (88% vs. 25%). Whereas recent studies of IDO1 inhibitors have shown mixed results, this study suggests that patients with anal cancer with high IDO1 expression have dismal prognosis and may represent a patient population primed for response to targeted IDO1 inhibition.

Outcomes following liver SBRT for metastatic pancreatic cancer

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Background: Traditionally, the role of localized therapy for metastatic pancreatic cancer (MPC) has been limited. However, with more effective systemic therapies, recent studies have explored a potential role for local therapies. We aimed to report outcomes following SBRT (stereotactic body radiation therapy) for liver metastases (LM) in setting of MPC and to identify predictors of response. Methods: 41 patients who underwent ablative RT to LM for MPC (2005-17) were retrospectively identified. Median RT dose was 50 Gy (range: 8-60 Gy), delivered in 5-6 fractions. Kaplan Meier method was used to calculate local control (LC), progression-free survival (PFS) and overall survival (OS). Univariate (UVA) and multivariate (MVA) Cox proportional hazards models were used to identify predictors of clinical outcomes. Results: Median follow up was 14.6 months. This cohort included 19 men and 22 women. 61% of pts had metachronous LM, 39% had synchronous LM. At time of RT, the treated lesion was stable /responding to chemotherapy (CTX) in 36.6% of pts; 46.3% were progressing with mixed response; 17% were off/refused CTX. Median number of prior CTX regimens was 2 (range: 0-5). Median number of LM was 1 (range: 1-4). Median pre-RT CEA was 7 ng/mL, median pre-RT CA19-9 was 354 U/ml. The 12-month outcomes were 75.8% LC, 16.5% PFS, and 36.3% OS. 8/41 (20%) patients were off CTX for ≥ 4 months. On UVA for LC, pre-RT CA19-9 (log10 scale) was associated with LC (HR 2.28, p = 0.03). Timing of LM, CTX response of LM, number of lesions, RT dose and CEA did not predict LC. On UVA for PFS, extrahepatic disease at time of RT was associated with worse PFS (HR: 2.47, p = 0.04), and response to CTX (progressive vs. stable/responding) approached significance (HR 1.83, p = 0.10). On UVA for OS, lower pre-RT CEA (HR 1.009, p = 0.03), lower pre-RT CA19-9 (HR 1.67, p = 0.01), and response to CTX (HR 6.42, p < 0.001) were associated with improved OS. On MVA for OS, response to CTX at time of liver RT remained significant for OS. Conclusions: SBRT of LM for MPC offers high rate of LC. In a small subset of patients, SBRT to LM may offer prolonged duration off systemic therapy. Lower pre-RT CA 19-9 and CEA, absence of extrahepatic disease, and stability/response of CTX at time of liver RT may select for patients most likely to benefit.

Protons versus Photons for Unresectable Hepatocellular Carcinoma: Liver Decompensation and Overall Survival

PURPOSE

Ablative radiation therapy is increasingly being used for hepatocellular carcinoma (HCC) resulting in excellent local control rates; however, patients without evidence of disease progression often die from liver failure. The clinical benefit of proton- over photon-based radiation therapy is unclear. We therefore sought to compare clinical outcomes of proton versus photon ablative radiation therapy in patients with unresectable HCC.

METHODS AND MATERIALS

This is a single-institution retrospective study of patients treated during 2008 to 2017 with nonmetastatic, unresectable HCC not previously treated with liver-directed radiation therapy and who did not receive further liver-directed radiation therapy within 12 months after completion of index treatment. The primary outcome, overall survival (OS), was assessed using Cox regression. Secondary endpoints included incidence of non-classic radiation-induced liver disease (defined as increase in baseline Child-Pugh score by ≥2 points at 3 months posttreatment), assessed using logistic regression, and locoregional recurrence, assessed using Fine-Gray regression for competing risks. All outcomes were measured from radiation start date.

RESULTS

The median follow-up was 14 months. Of 133 patients with median age 68 years and 75% male, 49 (37%) were treated with proton radiation therapy. Proton radiation therapy was associated with improved OS (adjusted hazard ratio, 0.47; P = .008; 95% confidence interval [CI], 0.27-0.82). The median OS for proton and photon patients was 31 and 14 months, respectively, and the 24-month OS for proton and photon patients was 59.1% and 28.6%, respectively. Proton radiation therapy was also associated with a decreased risk of non-classic radiation-induced liver disease (odds ratio, 0.26; P = .03; 95% CI, 0.08-0.86). Development of nonclassic RILD at 3 months was associated with worse OS (adjusted hazard ratio, 3.83; P < .001; 95% CI, 2.12-6.92). There was no difference in locoregional recurrence, including local failure, between protons and photons.

CONCLUSIONS

Proton radiation therapy was associated with improved survival, which may be driven by decreased incidence of posttreatment liver decompensation. Our findings support prospective investigations comparing proton versus photon ablative radiation therapy for HCC.

Elective nodal irradiation with simultaneous integrated boost stereotactic body radiotherapy for pancreatic cancer: Analyses of planning feasibility and geometrically driven DVH prediction model

PURPOSE

We evaluate the feasibility of the elective nodal irradiation strategy in stereotactic body radiotherapy (SBRT) for pancreatic cancer.

METHODS

Three simultaneous integrated boost (SIB)-SBRT plans (Boost1, Boost2, and Boost3) were retrospectively generated for each of 20 different patients. Boost1 delivered 33 and 25 Gy to PTV1 and PTV2, respectively. Boost2 delivered 40, 33, and 25 Gy to boostCTV, PTV1, and PTV2, respectively. Boost3 delivered 33 and 25 Gy to PTV1 and PTV3, respectively. PTV1 covered the initial standard SBRT plan (InitPlan) gross tumor volume (GTV). PTV2 covered CTVgeom which was created by a 10-mm expansion (15 mm posterior) of GTV. PTV3 covered CTVprop which included elective nodal regions. The boostCTV included GTV as well as involved vasculature. The planning feasibility in each scenario and dose-volume histograms (DVHs) were analyzed and compared with the InitPlan (delivered 33 Gy only to PTV1) by paired t-test. Next, a novel DVH prediction model was developed and its performance was evaluated according to the prediction accuracy (AC) of planning violations. Then, the model was used to simulate the impacts of GTV-to-organs at risk (OAR) distance and gastrointestinal (GI) OAR volume variations on planning feasibility.

RESULTS

Significant dose increases were observed in GI-OARs in SIB-SBRT plans when compared with InitPlan. All dose constraints were met in 63% of cases in InitPlan, Boost1, and Boost2, whereas Boost3 developed DVH violations in all cases. Utilizing previous patient anatomy, the novel DVH prediction model achieved a high AC in the prediction of violations for GI-OARs; the positive predictive value, negative predictive value, and AC were 66%, 90%, and 84%, respectively. Experiments with the model demonstrated that the larger proximity volume of GI-OAR at the shorter distance substantially impacted on planning violations.

CONCLUSIONS

SIB-SBRT plan with geometrically defined prophylactic areas can be dosimetrically feasible, but including all nodal areas with 25 Gy in five fractions appears to be unrealistic.

Enrichment of HER2 Amplification in Brain Metastases from Primary Gastrointestinal Malignancies

BACKGROUND

In nongastric gastrointestinal (GI) cancers, HER2-positive (HER2+) disease is not common. In breast cancer, HER2 status is associated with increased risk of brain metastases and response to HER2-targeted therapy. The purpose of this project was to compare HER2 status in GI cancer brain metastases versus matched prior sites of disease in order to determine if HER2+ disease is more common intracranially.

MATERIALS AND METHODS

We identified 28 patients with GI cancer who had craniotomy for brain metastases between 1999 and 2017 with intracranial metastatic tissue available at Massachusetts General Hospital. Twenty-four patients also had tissue from a prior site of disease. Fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) for HER2 were performed on all samples. A tumor was defined as HER2+ if it had 3+ staining by IHC or amplification by FISH.

RESULTS

A prior site of disease (including intracranial metastases) was HER2+ for 13% of evaluable patients: 3 of 11 patients with colorectal cancer and no patients with esophageal or pancreatic cancer. The most recent brain metastases were HER2+ for 32% of patients: 2 of 3 esophageal squamous cell carcinomas, 3 of 10 esophageal adenocarcinomas (ACs), 3 of 14 colorectal ACs, and 1 of 1 pancreatic AC. Only 37.5% of patients with HER2+ brain metastasis had concordant HER2+ prior tissue (κ = 0.38, p = .017).

CONCLUSION

In this cohort of patients with GI cancer with brain metastases, HER2+ status was more common intracranially compared with prior sites of disease. These findings suggest that testing HER2 in patients with GI cancer with brain metastases may lead to additional therapeutic options, regardless of HER2 status in previously examined tissue.

IMPLICATIONS FOR PRACTICE

HER2 amplification is a well-known driver of oncogenesis in breast cancer, with associated increased risk of brain metastases and response to HER2-directed therapy. In nongastric gastrointestinal (GI) cancers, HER2 amplification is not common and consequently is infrequently tested. The current study shows that brain metastases in patients with GI primary malignancies have a relatively high likelihood of being HER2 positive despite HER2 amplification or overexpression being less commonly found in matched tissue from prior sites of disease. This suggests that regardless of prior molecular testing, patients with GI cancer with brain metastases who have tissue available are likely to benefit from HER2 assessment to identify potential novel therapeutic options.

Association Between Very Small Tumor Size and Decreased Overall Survival in Node-Positive Pancreatic Cancer

BACKGROUND

In pancreatic adenocarcinoma (PDAC), increasing tumor size usually correlates with a worse prognosis. However, patients with a very small primary tumor who experience lymph node involvement may have a different disease biology. This study sought to determine the interaction between tumor size and lymph node involvement in terms of overall survival (OS).

METHODS

The study identified 17,073 patients with a diagnosis of M0 resected PDAC between 1983 and 2013 using the Surveillance, Epidemiology, and End Results database. The patients were stratified by lymph node involvement (N0 vs N+) and T stage (T1a-T1b vs T1c vs T2 vs T3 vs T4). The Kaplan-Meier method was used to estimate OS, and Cox regression analysis was used to compare survival between subgroups after adjustment for patient-specific factors.

RESULTS

Lymph node involvement and T stage significantly interacted (p < 0.001). Among the patients with node-negative disease, 5-year OS decreased monotonically with increasing T stage (59.1%, 30.6%, 22.9%, 16.6%, and 8.0%, respectively; p < 0.001). In contrast, among the patients with node-positive disease, those with T1a-T1b tumors (< 10 mm) had worse 5-year OS than those with T1c tumors (7.4% vs 17.6%; adjusted hazard ratio, 0.70; 95% confidence interval, 0.50-0.97; p = 0.034) and similar survival compared with those who had T2, T3, or T4 tumors (9.7%, 8.2%, and 4.8%, respectively; p > 0.2 in all cases).

CONCLUSIONS

Among patients with lymph node-positive PDAC, very small primary tumors are associated with decreased OS. This finding raises the possibility that small tumors capable of lymph node metastasis might represent more biologically aggressive cancers.

Primary tumor sidedness is an independent prognostic marker for survival in metastatic colorectal cancer: Results from a large retrospective cohort with mutational analysis

Recent reports demonstrate inferior outcomes associated with primary right‐sided vs left‐sided colorectal tumors in patients with metastatic colorectal cancer (mCRC). We sought to describe our experience with mCRC patients on whom we have molecular data to determine whether primary tumor sidedness was an independent prognostic marker for overall survival (OS). mCRC patients with documented primary tumor sidedness who received mutational profiling between 2009 and 2014 were identified (n = 367, median follow‐up 30.4 months). Mutational profiling for >150 mutations across commonly mutated cancer genes including RAS, PIK3CA, BRAF, and PTEN as well as treatment data, including receipt of a biologic agent, were collected. Univariable/multivariable models were used to analyze relationships between collected data and OS. Among 367 patients, sidedness breakdown was as follows: 234 left (64%), 133 right (36%). 56% were male, with a median age at diagnosis of 57 (range 24‐89). A total of 143 patients had RAS mutations. Five‐year OS was 41%, median OS was 54 months (range 1‐149). Five‐year OS for left‐ vs right‐sided tumors was 46% vs 24% (P < .0001). On univariable analysis, among both RAS wildtype and mutant tumors, left‐sided tumors continued to have improved OS vs right‐sided tumors (HR: 0.49, 95% CI: 0.34‐0.69 RAS wildtype; HR: 0.61, 95% CI: 0.40‐0.95 RAS mutant). Left‐sidedness was an important prognostic factor for OS among RAS wildtype patients despite treatment with or without a biologic agent (P < .05). Left‐sidedness remained significant for improved OS on multivariable analysis (P < .0001). Left‐sided primary tumor remained most important prognostic factor for OS, even when adjusting for mutational status and receipt of biologic agent.

Liver reirradiation for patients with hepatocellular carcinoma and liver metastasis

PURPOSE

This study aimed to assess the safety and efficacy of administering liver reirradiation to patients with primary liver tumors or liver metastasis.

METHODS AND MATERIALS

A total of 49 patients (with 64 individual tumors) who received liver reirradiation at our institution between June 2008 and December 2016 were identified for retrospective review. Patients were treated to the same, different, or a combination of previously treated liver tumors for recurrent primary (53%) or metastatic (47%) disease using photons or protons. Clinical and treatment-related factors were compiled and patients were monitored for toxicity and evidence of classic or nonclassic radiation-induced liver disease. Survival was estimated with the Kaplan-Meier method and cumulative incidence of local failure (LF) was used to estimate LF using the Response Evaluation Criteria in Solid Tumors version 1.1.

RESULTS

The median age at the time of reirradiation was 72 years and the median interval between radiation courses was 9 months. At a median follow-up of 10.5 months, 36 patients (73%) had died, 9 patients (18%) were alive, and 4 patients (8%) were lost to follow-up. The median survival for the cohort was 14 months. The overall 1-year estimate of LF was 46.4%. The 1-year estimates of LF for liver metastases and hepatocellular carcinoma were 61.0% and 32.5%, respectively. The average prescription dose was similar between the reirradiation and initial courses (equivalent dose in 2 Gy fractions EQD2: 65.0 vs 64.3 Gy_{α/β = 10}, respectively) but the average dose to the untreated liver was lower at the time of reirradiation (EQD2: 10.5 vs 13.9 Gy_{α/β = 3}, respectively, P = .01). Among patients with hepatocellular carcinoma, the average normal liver dose was significantly larger for patients who exhibited a worsening of Child-Pugh score after reirradiation compared with those who did not (1210 cGy vs 759 cGy, P = .04). With regard to toxicity, 85.7% of patients experienced grade 1 to 2 toxicity, 4.1% developed grade 3, and only 2 patients (4.1%) met the criteria for radiation-induced liver disease after reirradiation.

CONCLUSIONS

Liver reirradiation may be an effective and safe option for select patients; however, further prospective study is necessary to establish treatment guidelines and recommended dosing.

Differential Association Between Circulating Lymphocyte Populations With Outcome After Radiation Therapy in Subtypes of Liver Cancer

PURPOSE

Irradiation may have significant immunomodulatory effects that impact tumor response and could potentiate immunotherapeutic approaches. The purposes of this study were to prospectively investigate circulating lymphoid cell population fractions during hypofractionated proton therapy (HPT) in blood samples of liver cancer patients and to explore their association with survival.

METHODS AND MATERIALS

We collected serial blood samples before treatment and at days 8 and 15 of HPT from 43 patients with liver cancer-22 with hepatocellular carcinoma (HCC) and 21 with intrahepatic cholangiocarcinoma (ICC)-enrolled in a phase 2 clinical trial. All patients received 15 fractions of proton therapy to a median dose of 58 Gy (relative biological effectiveness). We used flow cytometry to measure the changes in the fractions of total CD3⁺, CD4⁺, and CD8⁺ T cells; CD4⁺ CD25⁺ T cells; CD4⁺ CD127⁺ T cells; CD3⁺ CD8⁺ CD25⁺ activated cytotoxic T lymphocytes (CTLs); and CD3^- CD56⁺ natural killer cells.

RESULTS

With a median follow-up period of 42 months, median overall survival (OS) in the study cohort was 30.6 months for HCC and 14.5 months for ICC patients. Longer OS was significantly correlated with greater CD4⁺ CD25⁺ T-cell (P = .003) and CD4⁺ CD127⁺ T-cell (P = .01) fractions at baseline only in ICC patients. In HCC patients, the fraction of activated CTLs mid treatment (at day 8) was significantly associated with OS (P = .007). These findings suggest a differential relevance of immunomodulation by HPT in these liver cancers.

CONCLUSIONS

Antitumor immunity may depend on maintenance of a sufficiently high number of activated CTLs during HPT in HCC patients and CD4⁺ CD25⁺ T cells and CD4⁺ CD127⁺ T cells prior to treatment in ICC patients. These results could guide the design of future studies to determine the optimal treatment schedules when combining irradiation with specific immunotherapy approaches.

Preoperative chemoradiotherapy versus postoperative chemoradiotherapy for local advanced gastric or Siewert II/III GEJ cancer: A retrospective analysis

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Background: Radiation therapy has improved survival in gastric cancer in some randomized trials. However, post-operative fields have been difficult tolerate, and completion rates have been low. Preoperative therapy may afford the opportunity to radical therapy, and potentially improve the resectability in advanced patients. Methods: Patients with Siewert II/III GE junction or gastric cancer treated at Massachusetts General Hospital were evaluated with Institutional Review Board approval. Clinical parameters and prognostic factors including gender, age, clinical stage, pathological stage, radiation parameters, concurrent chemotherapy, non-radiation chemotherapy, toxicity and survival were included in the analysis. Results: From Jul 2005 to Jan 2017, we enrolled 88 patients had chemoradiotherapy (CRT) and surgery, 48 preoperative and 40 postoperative CRT patients. In the preoperative group, 16.7% (8/48) had nodes outside a standard D2 dissection range, and the pathologic complete regression (pCR) rate was 18.8% (9/48). Median preoperative and postoperative radiation dose was 50.4 Gy and 45 Gy. Two-drug regimen was the most commonly used preoperative concurrent chemotherapy: 60.5% and single drug was the most commonly used postoperative concurrent chemotherapy: 97.5%. Except concurrent chemotherapy, 25 preoperative CRT patients received induction FOLFOX (median 8 cycles); 9 postoperative CRT patients also received 5-FU and 23 received FOLFOX (or EOX) chemotherapy. The estimated 3-year relapse-free survival (RFS) and overall survival (OS) in the preoperative and postoperative group was 51% vs. 34.3% (p = 0.286), and 71.2% vs. 45.9% (p = 0.179), respectively. In preoperative CRT group, there was more hematological toxicity but less gastrointestinal toxicity than postoperative CRT group, more distant metastasis but less peritoneal recurrence rate. Conclusions: Compared to postoperative chemoradiotherapy, preoperative chemoradiotherapy option has the trend of better tolerance, higher RFS and OS in patients with local advanced gastric cancer. Different chemoradiotherapy strategy may lead to different recurrence patterns.

HER2 positivity in brain metastases from gastrointestinal primary malignancies

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Background: HER2 amplification in gastrointestinal (GI) cancers, beyond gastric cancer, is uncommon and as a result infrequently tested. In breast cancer, HER2 amplification has been associated with brain metastases (BM) with associated prognostic value and therapeutic opportunity. The purpose of this project was to determine if HER2 amplification is more frequent in GI cancer patients with brain metastases. Methods: Retrospective review of our institution’s medical record system identified all patients with GI primary malignancies who had resection of BM between 1999-2015 with tissue available. Fluorescence in-situ hybridization for HER2 amplification and immunohistochemistry for HER2 expression was performed on each sample and quantified by a board-certified pathologist. Results: Twenty-five GI cancer patients with BM were identified: 40% esophageal adenocarcinoma (AC), 12% esophageal squamous cell carcinoma (SCC), 44% colorectal AC and 4% pancreatic AC. At diagnosis 36% had metastatic disease. A BM was the isolated first site of metastasis in: 11/13 esophageal cancers, 1/11 colorectal cancers and 1/1 pancreatic cancer. Two esophageal cancer patients and one colon cancer patient had BM at diagnosis but otherwise median time to BM was 30 months (range 4-127 months). There was a median of 1 BM with a maximum of 4 lesions per patient. The most common intracranial site was the cerebellum (40%) with a median metastasis size of 27 mm (range 5-55 mm). Overall, HER2 was amplified in 24% (n=6) with 4 of these patients having paired primary tumor tissue available. None of the primary tumor tissue was HER2 amplified. No colorectal cancer patients had HER2 amplification but 67% of esophageal SCC, 30% of esophageal AC and the only pancreatic AC patient had Her2 amplified and overexpressed brain metastases. Conclusions: HER2 amplification was enriched in esophageal SCC and AC patients who developed resectable BM despite none of these patients having HER2 amplification in their primary tissue. HER2 amplification testing in esophageal cancer patients with BM (regardless of histology) may lead to additional therapeutic options, even if primary tissue was negative for HER2 amplification.

The immune milieu of anal squamous cell carcinoma and implications of IDO expression on outcome

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Background: Recent studies have examined the immune microenvironment in anal squamous cell carcinoma (ASCC) with focus on T-cell infiltrate and PD-1/-L1 expression. This study examines a variety of immune markers in our institution’s pre-treatment localized ASCC cohort including indoleamine-2,3-dioxygenase 1 (IDO1) and class I HLA (hc10) which have not been previously studied in ASCC. Methods: Retrospective review identified 48 patients with localized ASCC treated at our institution with definitive chemoradiation between 2006-2016 with ≥6 months of follow-up in survivors and tissue locally available. Immunohistochemistry (IHC) for the immune markers CD8, PD1, PDL1, HLA class I (hc10) and IDO1 was performed and scored by two pathologists. Univariate and multivariate analyses were performed using a Cox proportional hazards model. Results: Of the 48 patients studied, distribution by stage was: I-14.5%, II-33%, IIIA-14.5%, IIIB-35%, unknown-2% with 27% having HIV or being on immunosuppressive medication. The distribution of immune marker staining was: median (med) CD8 72/hpf (0-319/hpf), med PD1 16/hpf (0-178/hpf), med PDL1 1% (0-40%), and med IDO1 3% (0-100%). Hc10 staining showed > 50% loss of HLA class I in 12.5% of patients. Spearman correlation calculations suggested that patients with high CD8 tended to have higher PD1 (R = 0.47, p = 0.0006) and tumor PDL1 (R = 0.36, p = 0.04) though hc10 and IDO1 expression were not correlated. Median follow-up for surviving patients was 35 months (6-102 months). CD8, PD1, PDL1 and hc10 expression did not correlate with clinical outcomes. However, IDO1 staining in > 50% of tumor cells was associated with worse outcomes, even when adjusted in a multivariable model for higher T-stage and nodal positivity: HR for progression 5.7 (95% CI 1.5-20.7, p = 0.008) and HR for death 5.6 (95% CI 1.5-21.5, p = 0.01). No other clinical variables were associated with outcome. Conclusions: ASCC has a diverse immune milieu. While patients generally do well with standard therapy, IDO1 may serve as a prognostic indicator of poor outcome and suggest a patient population in which IDO-directed therapies may prove particularly valuable.

Phase II Study of Proton-Based Stereotactic Body Radiation Therapy for Liver Metastases: Importance of Tumor Genotype

Background

We evaluated the efficacy and safety of risk-adapted, proton-based stereotactic body radiation therapy (SBRT) for liver metastases from solid tumors.

Methods

This single-arm phase II single institutional study (NCT01239381) included patients with limited extrahepatic disease, 800 mL or greater of uninvolved liver, and no cirrhosis or Child-Pugh A, who had received proton-based SBRT to one to four liver metastases from solid tumors. Treatment comprised 30 to 50 Gray equivalent (GyE) in five fractions based on the effective volume of liver irradiated. Sample size was calculated to determine if local control (LC) at one year was greater than 70%. The cumulative incidence of local failure was used to estimate LC. The association of tumor characteristics, including genetic alterations in common cancer genes such as BRAF, EGFR, HER2, KRAS, NRAS, PIK3CA, and TP53 with local tumor control, was assessed. All statistical tests were two-sided.

Results

Eighty-nine patients were evaluable (colorectal, n = 34; pancreatic, n = 13; esophagogastric, n = 12; other, n = 30). Median tumor size was 2.5 cm (range = 0.5-11.9 cm). Median dose was 40 GyE (range = 30-50 GyE), and median follow-up was 30.1 months (range = 14.7-53.8 months). There was no grade 3 to 5 toxicity. Median survival time was 18.1 months. The one- and three-year LC rates were 71.9% (95% confidence limit [CL] = 62.3% to 80.9%) and 61.2% (95% CL = 50.8% to 71.8%), respectively. For large tumors (≥6 cm), one-year LC remained high at 73.9% (95% CL = 54.6% to 89.8%). Mutation in the KRAS oncogene was the strongest predictor of poor LC (P = .02). Tumor with both mutant KRAS and TP53 were particularly radioresistant, with a one-year LC rate of only 20.0%, compared with 69.2% for all others (P = .001).

Conclusions

We report the largest prospective evaluation to date of liver SBRT for hepatic metastases, and the first with protons. Protons were remarkably well tolerated and effective even for metastases that were 6 cm or larger. KRAS mutation is a strong predictor of poor LC, stressing the need for tumor genotyping prior to SBRT and treatment intensification in this patient subset.

A retrospective comparison of neoadjuvant chemoradiotherapy regimens for locally advanced esophageal cancer

Preoperative chemoradiotherapy (CRT) with carboplatin/paclitaxel has been shown to increase survival in patients with esophageal cancer, including gastroesophageal junction (GE) junction cancer, over surgery alone; however, there have been no studies comparing the different neoadjuvant CRT regimens. We retrospectively evaluated the long-term results of trimodality therapy for patients with locally advanced esophageal cancer treated on several chemotherapy regimens. Between 1999 and 2014, 215 patients with locally advanced esophageal cancer underwent neoadjuvant CRT followed by surgical resection. The median age was 62 years (range 21-84), 80.5% were men and 86% had adenocarcinoma. The following chemotherapy regimens were administered: cisplatin/5FU (14.9%), cisplatin/irinotecan (35.8%), carboplatin/paclitaxel (35.8%), and other (9.7%). The majority of patients (92.1%) received a radiation dose of 50.4 Gy. Predictors of toxicities and surgical complications were assessed using logistic regression. Overall survival (OS) and recurrence-free survival (RFS) were estimated using the Kaplan-Meier method and proportional hazards regression was used to model time-to-event outcomes. The median follow-up among surviving patients was 4.1 years (range 0.4,13). The median OS was 3.0 years from time of diagnosis and OS was 36.8% at 5 years. RFS was 34.9% at 5 years. After neoadjuvant CRT, 34.7% of patients achieved a pathologic complete response including 60.7% of squamous cell carcinoma patients and 18.4% of adenocarcinoma patients (P < 0.001) and 66% were downstaged. Of the variables examined, pathologic stage, preoperative baseline cardiac comorbidity, postoperative cardiac or pulmonary complications, and chemotherapy regimen were associated with OS. Using cisplatin and 5FU as the reference regimen, patients treated with carboplatin/paclitaxel had significantly improved OS (HR = 0.47, P = 0.017 after adjusting for surgery type, radiation modality, baseline cardiac comorbidity, and preoperative stage) with 5-year OS rate of 66%. The most common surgical complications were cardiac in 61 patients (28.5%) and pulmonary in 52 patients (24.3%). Cardiac complications were associated with age (OR 1.05, P = 0.007) and cardiac comorbidity (OR 2.6, P = 0.02) and pulmonary complications with female gender (OR 3.98, P < 0.001). Forty-four patients (20.5%) required readmission within 30 days of discharge, and readmission was associated with cardiac comorbidity (OR 2.7, P = 0.017). Three patients died within 30 days of surgery. We observed an association between neoadjuvant carboplatin/paclitaxel and improved overall survival that requires confirmation in a prospective randomized trial.

The Impact of Pathologic Complete Response in Patients with Neoadjuvantly Treated Locally Advanced Rectal Cancer-a Large Single-Center Experience

Small cohort studies demonstrated better oncologic outcomes for patients with pathologic complete response (PathCR) after neoadjuvant treatment for locally advanced rectal cancer. This study reviews long-term outcomes of a large cohort of clinically stage II/III rectal cancer patients who received neoadjuvant chemoradiation and surgery. This is a retrospective analysis of a single-center cohort, including all clinical stage II/III rectal cancer patients who received neoadjuvant chemoradiation and surgery between 2004 and 2014 (n = 271). Cox regressions were done to assess the influence of PathCR on recurrence-free survival (RFS) and overall survival (OS), adjusting for postoperative chemotherapy, clinical AJCC staging, comorbidity, and age where appropriate. PathCR patients had significantly lower distant recurrence rates (4 vs. 15.8%; P = 0.028) and lower disease-specific mortality rates (0 vs. 8.1%; P = 0.052), compared to patients with residual disease. PathCR was associated with longer RFS (HR, 5.6 [95% CI 1.3-23.1] P = 0.018) and longer OS (HR, 3.4 [1.31-10.0] P = 0.014) compared to having pathological residual disease. This large single-center study shows that patients with PathCR have significant longer RFS and OS than patients with residual disease on pathology after neoadjuvant chemoradiation.