Elective clinical target volumes for conformal therapy in anorectal cancer: a radiation therapy oncology group consensus panel contouring atlas

PURPOSE

To develop a Radiation Therapy Oncology Group (RTOG) atlas of the elective clinical target volume (CTV) definitions to be used for planning pelvic intensity-modulated radiotherapy (IMRT) for anal and rectal cancers.

METHODS AND MATERIALS

The Gastrointestinal Committee of the RTOG established a task group (the nine physician co-authors) to develop this atlas. They responded to a questionnaire concerning three elective CTVs (CTVA: internal iliac, presacral, and perirectal nodal regions for both anal and rectal case planning; CTVB: external iliac nodal region for anal case planning and for selected rectal cases; CTVC: inguinal nodal region for anal case planning and for select rectal cases), and to outline these areas on individual computed tomographic images. The imaging files were shared via the Advanced Technology Consortium. A program developed by one of the co-authors (I.E.N.) used binomial maximum-likelihood estimates to generate a 95% group consensus contour. The computer-estimated consensus contours were then reviewed by the group and modified to provide a final contouring consensus atlas.

RESULTS

The panel achieved consensus CTV definitions to be used as guidelines for the adjuvant therapy of rectal cancer and definitive therapy for anal cancer. The most important difference from similar atlases for gynecologic or genitourinary cancer is mesorectal coverage. Detailed target volume contouring guidelines and images are discussed.

CONCLUSION

This report serves as a template for the definition of the elective CTVs to be used in IMRT planning for anal and rectal cancers, as part of prospective RTOG trials.

Long-course oxaliplatin-based preoperative chemoradiation versus 5 × 5 Gy and consolidation chemotherapy for cT4 or fixed cT3 rectal cancer: results of a randomized phase III study

BACKGROUND

Improvements in local control are required when using preoperative chemoradiation for cT4 or advanced cT3 rectal cancer. There is therefore a need to explore more effective schedules.

PATIENTS AND METHODS

Patients with fixed cT3 or cT4 cancer were randomized either to 5 × 5 Gy and three cycles of FOLFOX4 (group A) or to 50.4 Gy in 28 fractions combined with two 5-day cycles of bolus 5-Fu 325 mg/m(2)/day and leucovorin 20 mg/m(2)/day during the first and fifth week of irradiation along with five infusions of oxaliplatin 50 mg/m(2) once weekly (group B). The protocol was amended in 2012 to allow oxaliplatin to be then foregone in both groups.

RESULTS

Of 541 entered patients, 515 were eligible for analysis; 261 in group A and 254 in group B. Preoperative treatment acute toxicity was lower in group A than group B, P = 0.006; any toxicity being, respectively, 75% versus 83%, grade III-IV 23% versus 21% and toxic deaths 1% versus 3%. R0 resection rates (primary end point) and pathological complete response rates in groups A and B were, respectively, 77% versus 71%, P = 0.07, and 16% versus 12%, P = 0.17. The median follow-up was 35 months. At 3 years, the rates of overall survival and disease-free survival in groups A and B were, respectively, 73% versus 65%, P = 0.046, and 53% versus 52%, P = 0.85, together with the cumulative incidence of local failure and distant metastases being, respectively, 22% versus 21%, P = 0.82, and 30% versus 27%, P = 0.26. Postoperative and late complications rates in group A and group B were, respectively, 29% versus 25%, P = 0.18, and 20% versus 22%, P = 0.54.

CONCLUSIONS

No differences were observed in local efficacy between 5 × 5 Gy with consolidation chemotherapy and long-course chemoradiation. Nevertheless, an improved overall survival and lower acute toxicity favours the 5 × 5 Gy schedule with consolidation chemotherapy.

CLINICAL TRIAL NUMBER

The trial is registered as ClinicalTrials.gov number NCT00833131.

Effect of prehabilitation on objectively measured physical fitness after neoadjuvant treatment in preoperative rectal cancer patients: a blinded interventional pilot study

BACKGROUND

Patients requiring surgery for locally advanced rectal cancer often additionally undergo neoadjuvant chemoradiotherapy (NACRT), of which the effects on physical fitness are unknown. The aim of this feasibility and pilot study was to investigate the effects of NACRT and a 6 week structured responsive exercise training programme (SRETP) on oxygen uptake [Formula: see text] at lactate threshold ([Formula: see text]) in such patients.

METHODS

We prospectively studied 39 consecutive subjects (27 males) with T3-4/N+ resection margin threatened rectal cancer who completed standardized NACRT. Subjects underwent cardiopulmonary exercise testing at baseline (pre-NACRT), at week 0 (post-NACRT), and week 6 (post-SRETP). Twenty-two subjects undertook a 6 week SRETP on a training bike (three sessions per week) between week 0 and week 6 (exercise group). These were compared with 17 contemporaneous non-randomized subjects (control group). Changes in [Formula: see text] at [Formula: see text] over time and between the groups were compared using a compound symmetry covariance linear mixed model.

RESULTS

Of 39 recruited subjects, 22 out of 22 (exercise) and 13 out of 17 (control) completed the study. There were differences between the exercise and control groups at baseline [age, ASA score physical status, World Health Organisation performance status, and Colorectal Physiologic and Operative Severity Score for the Enumeration of Mortality and Morbidity (CR-POSSUM) predicted mortality]. In all subjects, [Formula: see text] at [Formula: see text] significantly reduced between baseline and week 0 [-1.9 ml kg(-1) min(-1); 95% confidence interval (CI) -1.3, -2.6; P<0.0001]. In the exercise group, [Formula: see text] at [Formula: see text] significantly improved between week 0 and week 6 (+2.1 ml kg(-1) min(-1); 95% CI +1.3, +2.9; P<0.0001), whereas the control group values were unchanged (-0.7 ml kg(-1) min(-1); 95% CI -1.66, +0.37; P=0.204).

CONCLUSIONS

NACRT before rectal cancer surgery reduces physical fitness. A structured exercise intervention is feasible post-NACRT and returns fitness to baseline levels within 6 weeks.

CLINICAL TRIAL REGISTRATION NCT

01325909.

An overview of 25 years of incidence, treatment and outcome of colorectal cancer patients

Regarding the continuous changes in the diagnostic process and treatment of colorectal cancer (CRC), it is important to evaluate long-term trends which are relevant in giving direction for further research and innovations in cancer patient care. The aim of this study was to analyze developments in incidence, treatment and survival for patients diagnosed with CRC in the Netherlands. For this population-based retrospective cohort study, all patients diagnosed with CRC between 1989 and 2014 in the Netherlands were identified using data of the nationwide population-based Netherlands Cancer Registry (n = 267,765), with follow-up until January 1, 2016. Analyses were performed for trends in incidence, mortality, stage distribution, treatment and relative survival measured from the time of diagnosis. The incidence of both colon and rectal cancer has risen. The use of postoperative chemotherapy for Stage III colon cancer increased (14-60%), as well as the use of preoperative (chemo)radiotherapy for rectal cancer (2-66%). The administration of systemic therapy and metastasectomy increased for Stage IV disease patients. The 5-year relative survival increased significantly from 53 to 62% for colon cancer and from 51 to 65% for rectal cancer. Ongoing advancements in treatment, and also improvement in other factors in the care of CRC patients-such as diagnostics, dedicated surgery and pre- and postoperative care-lead to a continuous improvement in the relative survival of CRC patients. The increasing incidence of CRC favors the implementation of the screening program, of which the effects should be monitored closely.

Local Cancer Recurrence: The Realities, Challenges, and Opportunities for New Therapies

Locoregional recurrence negatively impacts both long-term survival and quality of life for several malignancies. For appropriate-risk patients with an isolated, resectable, local recurrence, surgery represents the only potentially curative therapy. However, oncologic outcomes remain inferior for patients with locally recurrent disease even after macroscopically complete resection. Unfortunately, these operations are often extensive, with significant perioperative morbidity and mortality. This review highlights selected malignancies (mesothelioma, sarcoma, lung cancer, breast cancer, rectal cancer, and peritoneal surface malignancies) in which surgical resection is a key treatment modality and local recurrence plays a significant role in overall oncologic outcome with regard to survival and quality of life. For each type of cancer, the current, state-of-the-art treatment strategies and their outcomes are assessed. The need for additional therapeutic options is presented given the limitations of the current standard therapies. New and emerging treatment modalities, including polymer films and nanoparticles, are highlighted as potential future solutions for both prevention and treatment of locally recurrent cancers. Finally, the authors identify additional clinical and research opportunities and propose future research strategies based on the various patterns of local recurrence among the different cancers.

Inflammatory fibroblasts mediate resistance to neoadjuvant therapy in rectal cancer

Standard cancer therapy targets tumor cells without considering possible damage on the tumor microenvironment that could impair therapy response. In rectal cancer patients we find that inflammatory cancer-associated fibroblasts (iCAFs) are associated with poor chemoradiotherapy response. Employing a murine rectal cancer model or patient-derived tumor organoids and primary stroma cells, we show that, upon irradiation, interleukin-1α (IL-1α) not only polarizes cancer-associated fibroblasts toward the inflammatory phenotype but also triggers oxidative DNA damage, thereby predisposing iCAFs to p53-mediated therapy-induced senescence, which in turn results in chemoradiotherapy resistance and disease progression. Consistently, IL-1 inhibition, prevention of iCAFs senescence, or senolytic therapy sensitizes mice to irradiation, while lower IL-1 receptor antagonist serum levels in rectal patients correlate with poor prognosis. Collectively, we unravel a critical role for iCAFs in rectal cancer therapy resistance and identify IL-1 signaling as an attractive target for stroma-repolarization and prevention of cancer-associated fibroblasts senescence.

Long-course preoperative chemoradiation versus 5 × 5 Gy and consolidation chemotherapy for clinical T4 and fixed clinical T3 rectal cancer: long-term results of the randomized Polish II study

BACKGROUND

This trial evaluated whether preoperative short-course radiotherapy and consolidation chemotherapy (CCT) were superior to chemoradiation in rectal cancers with clinical (c)T4 or fixed cT3. Previously, we reported early results showing no differences in the radical surgery rate (primary end point). In the short-course/CCT group, we observed lower acute toxicity of preoperative treatment and better overall survival (OS). We updated results to determine whether the benefit in OS was sustained and to evaluate late complications.

PATIENTS AND METHODS

Patients with cT4 or fixed cT3 rectal cancer were randomized either to preoperative 5 × 5 Gy and three cycles of FOLFOX4 or to chemoradiation (50.4 Gy with bolus 5-Fu, leucovorin and oxaliplatin).

RESULTS

Patients (N = 515) were eligible for analysis, 261 in the short-course/CCT group and 254 in the chemoradiation group. The median follow-up was 7.0 years. The difference in OS was insignificant [hazard ratio (HR) 0.90; 95% confidence interval (CI) 0.70-1.15; P = 0.38). However, the difference in early OS favouring short-course/CCT previously reported was observed again, being 9% at 3 years (95% CI 0.5% to 17%). This difference disappeared later; at 8 years OS was 49% in both groups. There was no difference in disease-free survival (HR 0.95; 95% CI 0.75-1.19; P = 0.65) at 8 years 43% versus 41% in the short-course/CCT group versus the chemoradiation group, respectively. The corresponding values for cumulative incidences of local failure and distant metastases did not differ and were HR = 1.08, 95% CI 0.70-1.23, P = 0.60, 35% versus 32% and HR = 1.10, 95% CI 0.68-1.23, P = 0.54, 36% versus 34%, respectively. The rate of late complications was similar (P = 0.66), grade 3+ being 11% versus 9% in the short-course/CCT group versus the chemoradiation group, respectively.

CONCLUSION

The superiority of preoperative short-course/CCT over chemoradiation was not demonstrated.

CLINICAL TRIAL NUMBER

The trial is registered as ClinicalTrials.gov number NCT00833131.

Adjuvant 5FU plus levamisole in colonic or rectal cancer: improved survival in stage II and III

Based on the first favourable results of adjuvant therapy of 5FU plus levamisole in Dukes C colonic cancer in 1990, we conducted a prospective trial. 1029 patients were randomised to receive one year 5FU plus levamisole or no further treatment following curative surgery for stage II or III colon (n = 730) or rectal cancer (n = 299). 45% were in stage II and 55% in stage III. With a median follow-up of 4 years and 9 months a significant reduction in odds of death (25%, SD 9%, P = 0.007) was observed for those with adjuvant treatment (65% at 5 year) compared to the observation group (55%). Improved relative survival was present in stage III (56% vs 44%), and in stage II patients (78% vs 70%). In rectal cancer a non-significant difference in disease-free or overall survival was observed. Distant metastases developed in 76%, while local recurrence alone occurred in 14%. An early start of adjuvant treatment (< 4 weeks) did not affect results. Compliance to 5FU plus levamisole was 69%. Severe toxicity did not occur. In conclusion, one year 5FU plus levamisole was of benefit in stage II and III colonic cancer; in rectal cancer a significant positive effect could not be demonstrated.

Are Colon and Rectal Cancer Two Different Tumor Entities? A Proposal to Abandon the Term Colorectal Cancer

Colon cancer (CC) and rectal cancer (RC) are synonymously called colorectal cancer (CRC). Based on our experience in basic and clinical research as well as routine work in the field, the term CRC should be abandoned. We analyzed the available data from the literature and results from our multicenter Research Group Oncology of Gastrointestinal Tumors termed FOGT to confirm or reject this hypothesis. Anatomically, the risk of developing RC is four times higher than CC, while physical activity helps to prevent CC but not RC. Obvious differences exist in molecular carcinogenesis, pathology, surgical topography and procedures, and multimodal treatment. Therefore, we conclude that CC is not the same as RC. The term "CRC" should no longer be used as a single entity in basic and clinical research as well as other areas of classification.

Pattern of distant metastases in colorectal cancer: a SEER based study

More and more evidences suggest that primary colon and rectum tumors should not be considered as a single disease entity. In this manuscript, we evaluate the metastatic patterns of colon and rectum cancers and analyze the potential distribution of metastatic disease in these two malignancies. Data queried for this analysis include colorectal adenocarcinoma (2010-2011) from the Surveillance, Epidemiology, and End Results Program (SEER) database. Metastatic distribution information was provided for liver, lung, bone and brain. All of statistical analyses were performed using the Intercooled Stata 13.0 (Stata Corporation, College Station, TX). All statistical tests were two-sided. Totally, there were 46,027 eligible patients for analysis. We found that colon cancer had a higher incident rate of liver metastasis than rectum cancer (13.8% vs 12.3%), while rectum cancer had a higher incident rate of lung (5.6% vs 3.7%) and bone (1.2% vs 0.8%) metastasis than colon cancer, P<0.001. Colorectal cancer patients with lung metastasis had a higher risk of bone (10.0% vs 4.5%) or brain metastasis (3.1% vs 0.1%) than patients without lung metastases. The 1-year cause-specific survival was not significant different for bone or brain metastasis patients with and without lung metastasis (32.9% vs 38.7%, P=0.3834 for bone, 25.8% vs 36.9%, P=0.6819 for brain). Knowledge of these differences in metastatic patterns may help to better guide pre-treatment evaluation of colorectal cancer patients, especially in making determinations regarding curative-intent interventions.

Level of arterial ligation in rectal cancer surgery: low tie preferred over high tie. A review

Consensus does not exist on the level of arterial ligation in rectal cancer surgery. From oncologic considerations, many surgeons apply high tie arterial ligation (level of inferior mesenteric artery). Other strategies include ligation at the level of the superior rectal artery, just caudally to the origin of the left colic artery (low tie), and ligation at a level without any intraoperative definition of the inferior mesenteric or superior rectal arteries. Publications concerning the level of ligation in rectal cancer surgery were systematically reviewed. Twenty-three articles that evaluated oncologic outcome (n = 14), anastomotic circulation (n = 5), autonomous innervation (n = 5), and tension on the anastomosis/anastomotic leakage (n = 2) matched our selection criteria and were systematically reviewed. There is insufficient evidence to support high tie as the technique of choice. Furthermore, high tie has been proven to decrease perfusion and innervation of the proximal limb. It is concluded that neither the high tie strategy nor the low tie strategy is evidence based and that low tie is anatomically less invasive with respect to circulation and autonomous innervation of the proximal limb of anastomosis. As a consequence, in rectal cancer surgery low tie should be the preferred method.

Physical activity, sedentary behavior, and the risk of colon and rectal cancer in the NIH-AARP Diet and Health Study

OBJECTIVE

In order to prospectively investigate physical activity at varying intensities and sedentary behavior in relation to colorectal cancer.

METHODS

We considered 488,720 participants of the NIH-AARP Diet and Health Study who were aged 50-71 years at baseline in 1995-1996. Through 31 December, 2003, we identified 3,240 and 1,482 colorectal cancers among men and women, respectively. We estimated multivariable relative risks (RR) and 95% confidence intervals (CI) of colorectal cancer using Cox regression.

RESULTS

Engaging in exercise/sports five or more times per week compared to never or rarely exercising was associated with a reduced risk of colon cancer among men (p = 0.001; RR = 0.79, 95% CI = 0.68-0.91) and a suggestive decrease in risk among women (p = 0.376; RR = 0.85, 95% CI = 0.70-1.04). Engaging in exercise/sports was also associated with a decreased risk of rectal cancer in men (P = 0.074; RR comparing extreme categories = 0.76, 95% CI = 0.61-0.94). In men, we observed inverse relations of both low intensity (p = 0.017; RR = 0.81, 95% CI = 0.65-1.00 for > or =7 h/week) and moderate to vigorous intensity activity (p = 0.037; RR = 0.82, 95% CI = 0.67-0.99 for > or =7 h/week) to colon cancer risk. In contrast, sedentary behavior (time spent watching television/videos) was positively associated with colon cancer (p < 0.001; RR = 1.61, 95% CI = 1.14-2.27 for > or =9 h/day) among men. Similar, but less pronounced relations were observed in women.

CONCLUSION

Engaging in physical activity of any intensity is associated with reductions in colon and rectal cancer risk. Conversely, time spent sedentary is associated with increased colon cancer risk.

Comprehensive Genomic Landscapes in Early and Later Onset Colorectal Cancer

PURPOSE

The incidence rates of colorectal cancers are increasing in young adults. The objective of this study was to investigate genomic differences between tumor samples collected from younger and older patients with colorectal cancer.

EXPERIMENTAL DESIGN

DNA was extracted from 18,218 clinical specimens, followed by hybridization capture of 3,769 exons from 403 cancer-related genes and 47 introns of 19 genes commonly rearranged in cancer. Genomic alterations (GA) were determined, and association with patient age and microsatellite stable/microsatellite instability high (MSS/MSI-H) status established.

RESULTS

Overall genomic alteration rates in the younger (<40) and older (≥50) cohorts were similar in the majority of the genes analyzed. Gene alteration rates in the microsatellite stable (MSS) younger and older cohorts were largely similar, with several notable differences. In particular, TP53 (FDR < 0.01) and CTNNB1 (FDR = 0.01) alterations were more common in younger patients with colorectal cancer, and APC (FDR < 0.01), KRAS (FDR < 0.01), BRAF (FDR < 0.01), and FAM123B (FDR < 0.01) were more commonly altered in older patients with colorectal cancer. In the MSI-H cohort, the majority of genes showed similar rate of alterations in all age groups, but with significant differences seen in APC (FDR < 0.01), BRAF (FDR < 0.01), and KRAS (FDR < 0.01).

CONCLUSIONS

Tumors from younger and older patients with colorectal cancer demonstrated similar overall rates of genomic alteration. However, differences were noted in several genes relevant to biology and response to therapy. Further study will need to be conducted to determine whether the differences in gene alteration rates can be leveraged to provide personalized therapies for young patients with early-onset sporadic colorectal cancer.

Histological categorisation of fibrotic cancer stroma in advanced rectal cancer

BACKGROUND AND AIMS

Based on conflicting reports regarding the role of the fibrotic stromal response in cancer development--namely, that a desmoplastic reaction can favour either the host or the tumour--it is clear that the role of the stromal response is varied. We have classified the fibrotic stroma of rectal adenocarcinoma penetrating the muscularis propria, based on histologically identified stromal components.

METHODS

Three categories of stroma were used: mature-when the stroma was composed of mature collagen fibres (fine and elongated fibres into multiple layers); intermediate-when keloid-like collagen was intermingled with mature fibres; and immature-consisting of a myxoid stroma in which no mature fibres were included.

RESULTS

In a data set of 862 patients, 53% of patients had mature fibrotic cancer stroma, 33% had intermediate stroma, and 15% had immature stroma. Five year survival rates decreased as follows: mature stroma (80%), intermediate stroma (55%), and immature stroma (27%). The adverse tumour phenotype, tumour cell budding (conspicuous isolated cells or small clusters of cancer cells), was observed in the cancer fronts in tumours with unfavourable fibrotic stroma (p<0.0001). Based on multivariate analysis, categorised fibrotic stroma was selected as an independent prognostic parameter (hazard ratio 1.39; 95% confidence interval 1.17-1.64) together with tumour differentiation. By immunohistochemical examination, as maturation of the fibrotic stroma decreased, stromal T cells became significantly sparser. Furthermore, myofibroblasts were distributed extensively in immature fibrotic stroma compared with mature and intermediate fibrotic stroma.

CONCLUSION

The morphological categorisation of fibrotic cancer stroma highlights the role of the stromal response in relation to the behaviour and host immune reactions of rectal adenocarcinoma and would be a useful tool for predicting patient prognostic outcome.

Aspirin use and risk of colorectal cancer according to BRAF mutation status

IMPORTANCE

Aspirin use reduces the risk of colorectal carcinoma. Experimental evidence implicates a role of RAF kinases in up-regulation of prostaglandin-endoperoxide synthase 2 (PTGS2, cyclooxygenase 2), suggesting that BRAF-mutant colonic cells might be less sensitive to the antitumor effects of aspirin than BRAF-wild-type neoplastic cells.

OBJECTIVE

To examine whether the association of aspirin intake with colorectal cancer risk differs according to status of tumor BRAF oncogene mutation.

DESIGN AND SETTING

We collected biennial questionnaire data on aspirin use and followed up participants in the Nurses' Health Study (from 1980) and the Health Professionals Follow-up Study (from 1986) until July 1, 2006, for cancer incidence and until January 1, 2012, for cancer mortality. Duplication-method Cox proportional cause-specific hazards regression for competing risks data was used to compute hazard ratios (HRs) for colorectal carcinoma incidence according to BRAF mutation status.

MAIN OUTCOMES AND MEASURES

Incidence of colorectal cancer cases according to tumor BRAF mutation status.

RESULTS

Among 127,865 individuals, with 3,165,985 person-years of follow-up, we identified 1226 incident rectal and colon cancers with available molecular data. Compared with nonuse, regular aspirin use was associated with lower BRAF-wild-type cancer risk (multivariable HR, 0.73; 95% CI, 0.64 to 0.83; age-adjusted incidence rate difference [RD], -9.7; 95% CI, -12.6 to -6.7 per 100,000 person-years). This association was observed irrespective of status of tumor PTGS2 expression or PIK3CA or KRAS mutation. In contrast, regular aspirin use was not associated with a lower risk of BRAF-mutated cancer (multivariable HR, 1.03; 95% CI, 0.76 to 1.38; age-adjusted, incidence RD, 0.7; 95% CI, -0.3 to 1.7 per 100,000 person-years: P for heterogeneity = .037, between BRAF-wild-type vs BRAF-mutated cancer risks). Compared with no aspirin use, aspirin use of more than 14 tablets per week was associated with a lower risk of BRAF-wild-type cancer (multivariable HR, 0.43; 95% CI, 0.25 to 0.75; age-adjusted incidence RD, -19.8; 95% CI, -26.3 to -13.3 per 100,000 person-years). The relationship between the number of aspirin tablets per week and colorectal cancer risk differed significantly by BRAF mutation status (P for heterogeneity = .005).

CONCLUSIONS AND RELEVANCE

Regular aspirin use was associated with lower risk of BRAF-wild-type colorectal cancer but not with BRAF-mutated cancer risk. These findings suggest that BRAF-mutant colon tumor cells may be less sensitive to the effect of aspirin. Given the modest absolute risk difference, further investigations are necessary to determine clinical implications of our findings.

Predictive and Prognostic Molecular Biomarkers for Response to Neoadjuvant Chemoradiation in Rectal Cancer

The standard of care in locally advanced rectal cancer is neoadjuvant chemoradiation (nCRT) followed by radical surgery. Response to nCRT varies among patients and pathological complete response is associated with better outcome. However, there is a lack of effective methods to select rectal cancer patients who would or would not have a benefit from nCRT. The utility of clinicopathological and radiological features are limited due to lack of adequate sensitivity and specificity. Molecular biomarkers have the potential to predict response to nCRT at an early time point, but none have currently reached the clinic. Integration of diverse types of biomarkers including clinicopathological and imaging features, identification of mechanistic link to tumor biology, and rigorous validation using samples which represent disease heterogeneity, will allow to develop a sensitive and cost-effective molecular biomarker panel for precision medicine in rectal cancer. Here, we aim to review the recent advance in tissue- and blood-based molecular biomarker research and illustrate their potential in predicting nCRT response in rectal cancer.

Tumor hypoxia detected by positron emission tomography with 60Cu-ATSM as a predictor of response and survival in patients undergoing Neoadjuvant chemoradiotherapy for rectal carcinoma: a pilot study

PURPOSE

The response of rectal cancers to neoadjuvant chemoradiotherapy is variable. Tumor hypoxia reduces the effectiveness of both radiation therapy and chemotherapy and is a well-known risk factor for tumor radioresistence. We hypothesized that imaging with the novel hypoxia-detecting agent, (60)Cu-diacetyl-bis (N(4)-methylthiosemicarbazone) ((60)Cu-ATSM), previously validated in cervical and lung cancers, would predict the response of rectal cancers to neoadjuvant chemoradiotherapy and prognosis.

METHODS

Patients with locally invasive (T2-4) primary or node-positive rectal cancer located <12 cm from the anal verge were recruited for this pilot study. Pretreatment tumor size and stage were determined by endorectal ultrasonography, CT, and magnetic resonance imaging. Eleven patients also underwent clinical positron emission tomography with (18)F-fluorodeoxyglucose at the discretion of the treating clinician. The primary tumor was imaged by positron emission tomography with (60)Cu-ATSM, and accumulation of the tracer was measured semiquantitatively by determining the tumor-to-muscle activity ratio. Neoadjuvant chemoradiotherapy was then administered (within 2 weeks of (60)Cu-ATSM-positron emission tomography) and consisted of 45 Gy given in 25 fractions to the pelvis with continuous intravenous infusion of 5-fluorouracil (225 mg/m(2)/day). Proctectomy was performed six to eight weeks after neoadjuvant chemoradiotherapy and the tumor submitted to pathology for size measurement and staging. Tumor-to-muscle activity ratios were compared with tumor (18)F-fluorodeoxyglucose uptake, tumor response to neoadjuvant chemoradiotherapy, and with patient survival.

RESULTS

Nineteen patients were enrolled in the study, two of whom were excluded from final analysis (1 death during neoadjuvant chemoradiotherapy and 1 tumor perforation during neoadjuvant chemoradiotherapy requiring emergent surgery). Of the 17 remaining patients, 14 had a reduction in tumor size and 13 were downstaged. The median tumor-to-muscle activity ratio of 2.6 discriminated those with worse prognosis from those with better prognosis. Both overall and progression-free survivals were worse with hypoxic tumors (tumor-to-muscle activity ratio >2.6) than with nonhypoxic tumors (tumor-to-muscle activity ratio <or=2.6; both P < 0.05). In addition, 2 of the 3 tumors with no change in size had tumor-to-muscle activity ratios >2.6 (positive predictive value 66 percent), whereas 6 of 14 with decreased size had tumor-to-muscle activity ratios >2.6 (negative predictive value 57 percent). Three of the 4 tumors not downstaged had tumor-to-muscle activity ratios >2.6 (positive predictive value 75 percent), whereas 5 of 13 downstaged tumors had tumor-to-muscle activity ratios >2.6 (negative predictive value 62 percent). The mean tumor-to-muscle activity ratio for downstaged tumors (2.2) was significantly lower than that of nondownstaged tumors (3.3) (P = 0.03). The difference in mean tumor-to-muscle activity ratio between downsized (2.3) and nondownsized (2.9) tumors did not reach statistical significance (P = 0.36). Tumor (18)F-fluorodeoxyglucose uptake (n = 11) did not correlate with (60)Cu-ATSM uptake (r = 0.4; P = 0.9) and there was no significant difference in mean tumor (18)F-fluorodeoxyglucose uptake between patients with hypoxic tumors and those with normoxic tumors (P = 0.3).

CONCLUSIONS

The results of this small pilot study suggest that (60)Cu-ATSM-PET may be predictive of survival and, possibly, tumor response to neoadjuvant chemoradiotherapy in patients with rectal cancer. A larger Phase II study is warranted to validate these results.

Total neoadjuvant therapy for rectal cancer: An emerging option

The treatment of locally advanced rectal cancer (LARC) has benefited from improved surgical techniques and from the implementation of neoadjuvant chemoradiotherapy (CRT), which have markedly decreased the rates of local recurrence. However, distant metastatic disease remains the most significant cause of death for these patients. Although adjuvant chemotherapy (ChT) after neoadjuvant CRT and definitive surgery is commonly recommended, the value of adjuvant systemic therapy remains less clear. Trials evaluating adjuvant ChT for rectal cancer have been handicapped by poor compliance rates and inconsistent survival results. Shifting systemic therapy delivery to the neoadjuvant setting has the promise to improve compliance rates, reduce toxicity, and decrease distant relapse rates. Recently, multiple prospective trials have reported on the use of total neoadjuvant therapy (TNT) for patients with LARC, incorporating both ChT and CRT in the neoadjuvant setting. Here, the authors review the promising results from those trials. Because the studies have largely focused on pathologic outcomes (primarily pathologic complete response rates), ongoing phase 2 and 3 trials are now underway assessing the long-term disease-related outcomes with TNT. In addition to improving survival, TNT has the potential to increase the pool of patients with LARC who are eligible for organ preservation, which is also being evaluated. Cancer 2017;123:1497-1506. © 2017 American Cancer Society.

Textural Parameters of Tumor Heterogeneity in ¹⁸F-FDG PET/CT for Therapy Response Assessment and Prognosis in Patients with Locally Advanced Rectal Cancer

(18)F-FDG PET/CT is effective in the assessment of therapy response. Changes in glucose uptake or tumor size are used as a measure. Tumor heterogeneity was found to be a promising predictive and prognostic factor. We investigated textural parameters for their predictive and prognostic capability in patients with rectal cancer using histopathology as the gold standard. In addition, a comparison to clinical outcome was performed.

METHODS

Twenty-seven patients with rectal cancer underwent (18)F-FDG PET/CT before, 2 wk after the start, and 4 wk after the completion of neoadjuvant chemoradiotherapy. In all PET/CT scans, conventional parameters (tumor volume, diameter, maximum and mean standardized uptake values, and total lesion glycolysis [TLG]) and textural parameters (coefficient of variation [COV], skewness, and kurtosis) were determined to assess tumor heterogeneity. Values on pretherapeutic PET/CT as well as changes early in the course of therapy and after therapy were compared with histopathologic response. In addition, the prognostic value was assessed by correlation with time to progression and survival time.

RESULTS

The COV showed a statistically significant capability to assess histopathologic response early in therapy (sensitivity, 68%; specificity, 88%) and after therapy (79% and 88%, respectively). Thereby, the COV had a higher area under the curve in receiver-operating-characteristic analysis than did any analyzed conventional parameter for early and late response assessment. The COV showed a statistically significant capability to evaluate disease progression and to predict survival, although the latter was not statistically significant.

CONCLUSION

Tumor heterogeneity assessed by the COV, being superior to the investigated conventional parameters, is an important predictive factor in patients with rectal cancer. Furthermore, it can provide prognostic information. Therefore, its application is an important step for personalized treatment of rectal cancer.

Consolidation mFOLFOX6 Chemotherapy After Chemoradiotherapy Improves Survival in Patients With Locally Advanced Rectal Cancer: Final Results of a Multicenter Phase II Trial

BACKGROUND

Adding modified FOLFOX6 (folinic acid, fluorouracil, and oxaliplatin) after chemoradiotherapy and lengthening the chemoradiotherapy-to-surgery interval is associated with an increase in the proportion of rectal cancer patients with a pathological complete response.

OBJECTIVE

The purpose of this study was to analyze disease-free and overall survival.

DESIGN

This was a nonrandomized phase II trial.

SETTINGS

The study was conducted at multiple institutions.

PATIENTS

Four sequential study groups with stage II or III rectal cancer were included.

INTERVENTION

All of the patients received 50 Gy of radiation with concurrent continuous infusion of fluorouracil for 5 weeks. Patients in each group received 0, 2, 4, or 6 cycles of modified FOLFOX6 after chemoradiation and before total mesorectal excision. Patients were recommended to receive adjuvant chemotherapy after surgery to complete a total of 8 cycles of modified FOLFOX6.

MAIN OUTCOME MEASURES

The trial was powered to detect differences in pathological complete response, which was reported previously. Disease-free and overall survival are the main outcomes for the current study.

RESULTS

Of 259 patients, 211 had a complete follow-up. Median follow-up was 59 months (range, 9-125 mo). The mean number of total chemotherapy cycles differed among the 4 groups (p = 0.002), because one third of patients in the group assigned to no preoperative FOLFOX did not receive any adjuvant chemotherapy. Disease-free survival was significantly associated with study group, ypTNM stage, and pathological complete response (p = 0.004, <0.001, and 0.001). A secondary analysis including only patients who received ≥1 cycle of FOLFOX still showed differences in survival between study groups (p = 0.03).

LIMITATIONS

The trial was not randomized and was not powered to show differences in survival. Survival data were not available for 19% of the patients.

CONCLUSIONS

Adding modified FOLFOX6 after chemoradiotherapy and before total mesorectal excision increases compliance with systemic chemotherapy and disease-free survival in patients with locally advanced rectal cancer. Neoadjuvant consolidation chemotherapy may have benefits beyond increasing pathological complete response rates. See Video Abstract at http://links.lww.com/DCR/A739.

STAT3 inhibition sensitizes colorectal cancer to chemoradiotherapy in vitro and in vivo

Increased activity of signal transducer and activator of transcription 3 (STAT3) is common in human malignancies, including colorectal cancers (CRCs). We have recently reported that STAT3 gene expression correlates with resistance of CRC cell lines to 5-fluorouracil (5-FU)-based chemoradiotherapy (CT/RT). This is of considerable clinical importance, because a large proportion of rectal cancers are resistant to preoperative multimodal treatment. To test whether STAT3 contributes to CT/RT-resistance, we first confirmed that STAT3 protein expression correlated positively with increasing resistance. While STAT3 was not constitutively active, stimulation with interleukin-6 (IL-6) resulted in remarkably higher expression levels of phosphorylated STAT3 in CT/RT-resistant cell lines. A similar result was observed when we determined IL-6-induced expression levels of phosphorylated STAT3 following irradiation. Next, STAT3 was inhibited in SW480 and SW837 using siRNA, shRNA and the small-molecule inhibitor STATTIC. Successful silencing and inhibition of phosphorylation was confirmed using Western blot analysis and a luciferase reporter assay. RNAi-mediated silencing as well as STATTIC treatment resulted in significantly decreased clonogenic survival following exposure to 3 µM of 5-FU and irradiation in a dose-dependent manner, with dose-modifying factors of 1.3-2.5 at a surviving fraction of 0.37. Finally, STAT3 inhibition led to a profound CT/RT-sensitization in a subcutaneous xenograft model, with a significantly delayed tumor regrowth in STATTIC-treated mice compared with control animals. These results highlight a potential role of STAT3 in mediating treatment resistance and provide first proof of concept that STAT3 represents a promising novel molecular target for sensitizing resistant rectal cancers to CT/RT.

Can chemoradiation allow for omission of lateral pelvic node dissection for locally advanced rectal cancer?

OBJECTIVES

We evaluated the relationship between pretreatment clinical parameters and lateral pelvic node (LPN) recurrence in patients with rectal cancer treated with a combination of curative resection and chemoradiotherapy (CRT) and attempted to identify the patients who might benefit from LPN dissection.

METHODS

This study involved 900 patients between June 2001 and June 2009. Pretreatment clinical parameters including radiological size of LPN were analyzed to identify risk factors associated with long-term outcomes.

RESULTS

Locoregional recurrence developed in 65 patients (7.2%); 42 (64.6%) had LPN recurrence, 20 (47.6%) of which had no distant metastasis. Multivariate analysis showed that LPN short-axis diameter (<5, 5-<10, and ≥10 mm) was significantly associated with LPN recurrence-free survival (5-year survival rate (5YSR), 98.2, 91.7, and 40.1%, respectively, P < 0.05), locoregional recurrence-free survival (5YSR, 95.5, 87.6, and 40.1%, respectively, P < 0.05), relapse-free survival (5YSR, 76.8, 72.5, and 30.3, respectively, P < 0.05), and overall survival (5YSR, 86.3, 83.0, and 57.5%, respectively, P < 0.05).

CONCLUSIONS

Patients with an LPN short-axis diameter ≥10 mm represent a potential subgroup at a high risk of LPN recurrence, even after CRT. Further study is needed to confirm whether LPN dissection is beneficial for these patients.

Postoperative complications in patients with rectal cancer are associated with delays in chemotherapy that lead to worse disease-free and overall survival

OBJECTIVE

The objective of this study was to identify the risk factors for delays in chemotherapy after rectal cancer surgery and evaluate the effects of delayed therapy on long-term outcomes. We also sought to clarify what time frame should be used to define delayed adjuvant chemotherapy.

BACKGROUND

Postoperative complications have been found to influence the timing of chemotherapy in patients with colon cancer. Delays in chemotherapy have been shown to be associated with worse overall and disease-free survival in patients with colorectal cancer, although the timing of delay has not been agreed upon in the literature.

STUDY DESIGN

We performed a retrospective review of a prospectively maintained rectal cancer database. Univariate analysis was used to identify risk factors for delayed chemotherapy. Kaplan-Meier curves were generated to compare overall and disease-free survival in patients based on complications and timing of chemotherapy.

SETTINGS

This study was performed at the University of Wisconsin Hospital, Madison, Wisconsin, between 1995 and 2012.

PATIENTS

Patients with rectal cancer who underwent proctectomy with curative intent were included in this study.

OUTCOME MEASURES

Timing of chemotherapy, 30-day complications, and 30-day readmissions were the main outcome measures.

RESULTS

Postoperative complications and 30-day readmissions were associated with delays in chemotherapy ≥8 weeks after surgery. Patients who received chemotherapy ≥8 weeks postoperatively were found to have worse local and distant recurrence rates and worse overall survival in comparison with patients who received chemotherapy within 8 weeks of surgery.

LIMITATIONS

The limitations of this study include its retrospective nature and that it was performed at a single institution.

CONCLUSIONS

We found complications and readmissions to be risk factors for delayed chemotherapy. Patients who received therapy ≥8 weeks postoperatively had worse disease-free and overall survival.

A comparison of colon and rectal somatic DNA alterations

PURPOSE

Differences in acquired mutations in colon and rectal tumors may account for differences in risk factors. In this study, we examined similarities and differences in somatic alterations in colon and rectal tumors.

METHODS

Cases were identified from two large population-based case-control studies of colon cancer and rectal cancer. We sequenced Exons 5 to 8 of the p53 gene and Codons 12 and 13 of the Ki-ras gene to identify tumor mutations. Microsatellite instability was determined based on BAT26 and TGFbetaRII analysis; CpG island methylator phenotype was determined based on having two or more of the following markers methylated p16, MLH1, MINT1, MINT2, and MINT31.

RESULTS

p53 mutations were observed in 39.7% of proximal, 51.0% of distal, and 46.6% of rectal tumors; Ki-ras mutations were observed in 36.0% of proximal, 26.9% of distal, and 30.5% of rectal tumors. Although 40.9% of proximal tumors were considered CpG island methylator phenotype positive (having two or more of five markers methylated), only 12.9% of distal and 11.9% of rectal tumors were CpG island methylator phenotype positive. Likewise, microsatellite instability was observed in 23.7% of proximal and only 3.8% of distal and 2.0% of rectal tumors. More than 50% of distal colon or rectal tumors had only one acquired mutation, whereas only 35.1% of proximal tumors had one mutation. The most common single mutation for colon and rectal tumors was p53 followed by Ki-ras mutations.

CONCLUSIONS

Our findings suggest that unique mutational pathways are involved in the development of most colorectal tumors. Proximal colon cancers are more likely than rectal and distal colon tumors to have microsatellite instability, CpG island methylator phenotype, and Ki-ras mutations, whereas rectal and distal colon tumors are more likely than proximal colon tumors to have a p53 mutation. Overall, rectal and distal colon tumors share similar mutational frequencies which are different from those observed in proximal colon tumors.