Biomarkers and Molecular Imaging as Predictors of Response to Neoadjuvant Chemoradiotherapy in Patients With Locally Advanced Rectal Cancer

Targeted Next-Generation Sequencing-Based Multiple Gene Mutation Profiling of Patients with Rectal Adenocarcinoma Receiving or Not Receiving Neoadjuvant Chemoradiotherapy

This study investigated whether oncogenic and tumor-suppressive gene mutations are involved in the differential outcomes of patients with rectal carcinoma receiving neoadjuvant chemoradiotherapy (nCRT). Genomic DNA was obtained from formalin-fixed paraffin-embedded (FFPE) specimens of patients with rectal carcinoma who received a complete nCRT course. Gene mutation status was examined in specimens from patients before and after nCRT by using the AmpliSeq platform. Our data revealed that the nonsynonymous p53, APC, KRAS, CDKN2A, and EGFR mutations were observed in 93.1%, 65.5%, 48.6%, and 31% of the patients with rectal adenocarcinoma, respectively. BRAF, FBXW7, PTEN, and SMAD4 mutations were observed in 20.7% of patients with rectal carcinoma. The following 12 gene mutations were observed more frequently in the patients exhibiting a complete response than in those demonstrating a poor response before nCRT: ATM, BRAF, CDKN2A, EGFR, FLT3, GNA11, KDR, KIT, PIK3CA, PTEN, PTPN11, SMAD4, and TP53. In addition, APC, BRAF, FBXW7, KRAS, SMAD4, and TP53 mutations were retained after nCRT. Our results indicate a complex mutational profile in rectal carcinoma, suggesting the involvement of BRAF, SMAD4, and TP53 genetic variants in the outcomes of patients with nCRT.

Nucleic acid-based markers of response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer

The progress that has been made in the treatment of rectal cancer has mostly resulted from multimodality strategy approach that combines surgery, chemotherapy and radiotherapy. In locally advanced rectal cancer (LARC), surgery remains the primary treatment, while neoadjuvant chemoradiotherapy (nCRT) is used to downsize or downstage the tumor before surgical resection. Highly variable response to nCRT observed in LARC patients raises the need for biomarkers to enable prediction and evaluation of treatment response in a more efficient and timely manner than currently available tools. The search for predictive biomarkers continues beyond blood proteins, which have failed in subsequent validation studies. This review presents nucleic acids-based markers and their predictive potential in LARC patients. Most of the candidate biomarkers come from relatively small single-institution studies. The only candidate biomarker that emerged as relevant in more than a single study was elevated levels of Fusobacterium nucleatum nucleic acids in tumor tissue. Considering that this marker is easily accessible through non-invasive analysis of faecal samples, its predictive potential is worth further validation. The other candidate nucleic acid-based biomarkers require more consistent studies on larger cohorts before they can be considered for use in clinical setting.

The "Immunoscore" in rectal cancer: could we search quality beyond quantity of life?

Because of the function and anatomical environment of the rectum, therapeutic strategies for local advanced rectal cancer (LARC) must deal with two challenging stressors that are a high-risk of local and distal recurrences and a high-risk of poor quality of life (QoL). Over the last three decades, advances in screening tests, therapies, and combined-modality treatment options and strategies have improved the prognosis of patients with LARC. However, owing to the heterogeneous nature of LARC and genetic status, the patient may not respond to a specific therapy and may be at increased risk of side-effects without the life-prolonging benefit. Indeed, each therapy can cause its own side-effects, which may worsen by a combination of treatments resulting in long-term poor QoL. In LARC, QoL has become even more essential with the increasing incidence of rectal cancer in young individuals. Herein, we analyzed the value of the Immunoscore-Biopsy (performed on tumor biopsy at diagnosis) in predicting outcomes, alone or in association with clinical and imaging data, for each therapy used in LARC.

Evaluation of Efficacy and Tolerance of Radical Radiotherapy and Radiochemotherapy in Treatment of Locally Advanced, Unresectable Rectal Cancer

Background: A retrospective evaluation of tolerance and efficacy of two schemes of neoadjuvant treatment in patients (pts) with unresectable rectal cancer: radiochemotherapy (CRT) and radiotherapy (RT), including conventional and accelerated hyperfractionation. Material and Method: A total of 145 consecutive pts with unresectable, locally advanced rectal cancer. The schemes used are RT in 73 (50%) or CRT in 72 (50%). In CRT, 54 Gy in 1.8 Gy fractions was given with chemotherapy, In the RT group, conventional fractionation (CFRT) and hyperfractionated accelerated radiotherapy (HART). HART was introduced at first as an alternative to CFRT, after radiobiological studies suggesting a therapeutic gain of hyperfractionation in other cancers, and second to administer relatively high dose needed in unresectable cancer, which is not feasible in hypofractionation because of critical organs sensitivity to high fraction doses (fd). HART was an alternative option in pts with medical contraindications to chemotherapy and to shorten overall treatment time with greater radiobiological effectiveness than CFRT. Results: Objective response (OR) in the RT and CRT group was 60% versus 75%. Resection rate (RR) in RT and CRT: 37% versus 65%. Tumor mobility and laparotomy-based unresectability were significant factors for OR. Performance status (PS), tumor mobility, and neoadjuvant treatment method were significant for RR.

Current State of Neoadjuvant Radiotherapy for Rectal Cancer

Colorectal cancer is the third most commonly diagnosed cancer, with rectal cancer accounting for 30% of cases. The current standard of care curative treatment for locally advanced rectal cancer is (chemo)radiotherapy followed by surgery and adjuvant chemotherapy. Although neoadjuvant radiotherapy has reduced the risk of local recurrence to less than 10%, the risk of distant metastasis remained high at 30% affecting patient survival. In addition, there is a recognition that there is heterogeneity in tumor biology and treatment response with good responders potentially suitable for treatment de-escalation. Therefore, new treatment sequencing and regimens were investigated. Here, we reviewed the evidence for current neoadjuvant treatment options in patients with locally advanced rectal adenocarcinoma, and highlight the new challenges in this new treatment landscape.

Molecular and Dynamic Evaluation of Proteins Related to Resistance to Neoadjuvant Treatment with Chemoradiotherapy in Circulating Tumor Cells of Patients with Locally Advanced Rectal Cancer

The heterogeneity of response to neoadjuvant chemoradiotherapy (NCRT) is still a challenge in locally advanced rectal cancer (LARC). The evaluation of thymidylate synthase (TYMS) and RAD23 homolog B (RAD23B) expression in circulating tumor cells (CTCs) provides complementary clinical information. CTCs were prospectively evaluated in 166 blood samples (63 patients) with LARC undergoing NCRT. The primary objective was to verify if the absence of RAD23B/TYMS in CTCs would correlate with pathological complete response (pCR). Secondary objectives were to correlate CTC kinetics before (C1)/after NCRT (C2), in addition to the expression of transforming growth factor-β receptor I (TGF-βRI) with survival rates. CTCs were isolated by ISET and evaluated by immunocytochemistry (protein expression). At C1, RAD23B was detected in 54.1% of patients with no pCR and its absence in 91.7% of patients with pCR (p = 0.014); TYMS^- was observed in 90% of patients with pCR and TYMS⁺ in 51.7% without pCR (p = 0.057). Patients with CTC2 > CTC1 had worse disease-free survival (DFS) (p = 0.00025) and overall survival (OS) (p = 0.0036) compared with those with CTC2 ≤ CTC1. TGF-βRI expression in any time correlated with worse DFS (p = 0.059). To conclude, RAD23B/TYMS and CTC kinetics may facilitate the personalized treatment of LARC.

Prognostic Impact of Carcinoembryonic Antigen Levels in Rectal Cancer Patients Who Had Received Neoadjuvant Chemoradiotherapy

PURPOSE

Carcinoembryonic antigen (CEA) is a useful marker for rectal cancer. The aim of this study was to investigate the prognostic impact of CEA level according to neoadjuvant chemoradiotherapy (nCRT) in rectal cancer patients who underwent radical surgery.

METHODS

A total of 245 patients with rectal cancer who underwent radical surgery were retrospectively evaluated. Serum CEA level was measured preoperatively and postoperatively. We compared survival outcomes based on CEA level before and after surgery according to nCRT.

RESULTS

Of the 245 patients, elevation of CEA level was observed preoperatively in 79 and postoperatively in 30, respectively. Eighty-seven (35.5%) patients received nCRT, and elevated CEA level was a significant prognostic factor both before and after surgery. In patients who had not received nCRT, an elevated CEA level was a significant prognostic factor before surgery but was not significant after surgery. In a multivariate analysis for prognostic factors, elevation of preoperative CEA level was an independent prognostic factor of disease-free survival (DFS) regardless of nCRT. Postoperative CEA level was an independent prognostic factor of DFS in patients who had received nCRT but was not a factor in patients who had not received nCRT.

CONCLUSION

Serum CEA level was an independent prognostic factor both preoperatively and postoperatively in rectal cancer patients who had received nCRT.

A Comprehensive Evaluation of Associations Between Routinely Collected Staging Information and The Response to (Chemo)Radiotherapy in Rectal Cancer

Simple Summary

Rectal cancer patients are often treated with radiotherapy, either alone or combined with chemotherapy, prior to surgery to enable radical surgery on a non-resectable tumor or to lower the recurrence risk. For some patients, the tumor disappears completely after preoperative treatment, while others experience little or no benefit. Accurate prediction of therapy response before treatment is of great importance for a personalized treatment approach and intentional organ preservation. We performed a comprehensive evaluation of the predictive capacity of all routinely collected staging information at diagnosis in a population-based, completely staged patient material of 383 patients representing a real-life clinical situation. Size or stage of the rectal tumor were independent predictors of excellent response irrespective of preoperative treatment, with small/early-stage tumors being significantly more likely to reach a complete response. Levels of the tumor marker carcinoembryonic antigen (CEA) above upper normal limit halved the chance of response.

Abstract

Radiotherapy (RT) or chemoradiotherapy (CRT) are frequently used in rectal cancer, sometimes resulting in complete tumor remission (CR). The predictive capacity of all clinical factors, laboratory values and magnetic resonance imaging parameters performed in routine staging was evaluated to understand what determines an excellent response to RT/CRT. A population-based cohort of 383 patients treated with short-course RT (5 × 5 Gy in one week, scRT), CRT, or scRT with chemotherapy (scRT+CT) and having either had a delay to surgery or been entered into a watch-and-wait program were included. Complete staging according to guidelines was performed and associations between investigated variables and CR rates were analyzed in univariate and multivariate analyses. In total, 17% achieved pathological or clinical CR, more often after scRT+CT and CRT than after scRT (27%, 18% and 8%, respectively, p < 0.001). Factors independently associated with CR included clinical tumor stage, small tumor size (<3 cm), tumor level, and low CEA-value (<3.8 μg/L). Size or stage of the rectal tumor were associated with excellent response in all therapy groups, with small or early stage tumors being significantly more likely to reach CR (p = 0.01 (scRT), p = 0.01 (CRT) and p = 0.02 (scRT+CT). Elevated level of carcinoembryonic antigen (CEA) halved the chance of response. Extramural vascular invasion (EMVI) and mucinous character may indicate less response to RT alone.

A Nine-Gene Signature for Predicting the Response to Preoperative Chemoradiotherapy in Patients with Locally Advanced Rectal Cancer

Preoperative chemoradiotherapy (PCRT) and subsequent surgery is the standard multimodal treatment for locally advanced rectal cancer (LARC), albeit PCRT response varies among the individuals. This creates a dire necessity to identify a predictive model to forecast treatment response outcomes and identify patients who would benefit from PCRT. In this study, we performed a gene expression study using formalin-fixed paraffin-embedded (FFPE) tumor biopsy samples from 156 LARC patients (training cohort n = 60; validation cohort n = 96); we identified the nine-gene signature (FGFR3, GNA11, H3F3A, IL12A, IL1R1, IL2RB, NKD1, SGK2, and SPRY2) that distinctively differentiated responders from non-responders in the training cohort (accuracy = 86.9%, specificity = 84.8%, sensitivity = 81.5%) as well as in an independent validation cohort (accuracy = 81.0%, specificity = 79.4%, sensitivity = 82.3%). The signature was independent of all pathological and clinical features and was robust in predicting PCRT response. It is readily applicable to the clinical setting using FFPE samples and Food and Drug Administration (FDA) approved hardware and reagents. Predicting the response to PCRT may aid in tailored therapies for respective responders to PCRT and improve the oncologic outcomes for LARC patients.

Pathologic Complete Response Despite Nodal Yield Has Best Survival in Locally Advanced Rectal Cancer

BACKGROUND

Controversy exists regarding the ability of neoadjuvant chemoradiation (nCR) to diminish lymph node yield (LNY) and how that relationship is influenced by tumor response in patients undergoing proctectomy for locally advanced rectal cancer.

MATERIALS AND METHODS

The National Cancer Database was used to identify patients with rectal adenocarcinomas from 2004 to 2014. Patients that received nCR were compared with those that underwent surgery alone. LNY was stratified into <12 and ≥12 groups to determine their differences in stage specific overall survival.

RESULTS

Of 56,812 patients 46.5% underwent surgery alone and 53.5% were administered nCR. There were more patients with LNY<12 in the nCR group compared to surgery alone, across all stages (44.1% versus 36.5%, P < 0.001). nCR improved OS regardless of LNY (P < 0.001). Although patients with LNY≥12 had improved overall survival, patients who had a pathologic complete response (pCR) achieved the greatest survival. In patients that did not achieve a pCR, LNY≥12 was a marker of improved OS but LNY did not impact OS in patients that attained pCR (P < 0.001).

CONCLUSIONS

Although nCR diminished LNY, LNY≥12 improved OS demonstrating the importance of quality total mesorectal excision. However, LNY did not impact patients that achieved pCR. These patients, who achieved the best OS, demonstrated that tumors' biologic response to nCR had the greatest impact on patient outcomes.

Accurate outcome prediction after neo-adjuvant radio-chemotherapy for rectal cancer based on a TCP-based early regression index

•

A TCP-based early regression index (ERI_TCP) was previously introduced.

•

ERI_TCP was associated to improved survival after neo-adjuvant therapy for rectal cancer.

•

Distant-metastasis-free survival was predicted by ERI_TCP and 5-FU dose.

•

The resulting AUC (0.86) was significantly higher than models not including T ERI_TCP.

•

ERI_TCP is a promising tool for therapy personalization.

Background and purpose

An early tumor regression index (ERI_TCP) was previously introduced and found to predict pathological response after neo-adjuvant radio-chemotherapy of rectal cancer. ERI_TCP was tested as a potential biomarker in predicting long-term disease-free survival.

Materials and methods

Data of 65 patients treated with an early regression-guided adaptive boosting technique (ART) were available. Overall, loco-regional relapse-free and distant metastasis-free survival (OS, LRFS, DMFS) were considered. Patients received 41.4 Gy in 18 fractions (2.3 Gy/fr), including ART concomitant boost on the residual GTV during the last 6 fractions (3 Gy/fr, D_mean: 45.6 Gy). Chemotherapy included oxaliplatin and 5-fluorouracil (5-FU). T2-weighted MRI taken before (MRI_pre) and at half therapy (MRI_half) were available and GTVs were contoured (V_pre, V_half). The parameter ERI_TCP = −ln[(1 − (V_half/V_pre))^Vpre] was calculated for all patients. Cox regression models were assessed considering several clinical and histological variables. Cox models not including/including ERI_TCP (CONV_model and REGR_model respectively) were assessed and their discriminative power compared.

Results

At a median follow-up of 47 months, OS, LRFS and DMFS were 94%, 95% and 78%. Due to too few events, multivariable analyses focused on DMFS: the resulting CONV_model included pathological complete remission or clinical complete remission followed by surgery refusal (HR: 0.15, p = 0.07) and 5-FU dose >90% (HR: 0.29, p = 0.03) as best predictors, with AUC = 0.75. REGR_model included ERI_TCP (HR: 1.019, p < 0.0001) and 5-FU dose >90% (HR: 0.18, p = 0.005); AUC was 0.86, significantly higher than CONV_model (p = 0.05). Stratifying patients according to the best cut-off value for ERI_TCP and to 5-FU dose (> vs <90%) resulted in 47-month DMFS equal to 100%/69%/0% for patients with two/one/zero positive factors respectively (p = 0.0002). ERI_TCP was also the only variable significantly associated to OS (p = 0.01) and LRFS (p = 0.03).

Conclusion

ERI_TCP predicts long-term DMFS after radio-chemotherapy for rectal cancer: an independent impact of the 5-FU dose was also found. This result represents a first step toward application of ERI_TCP in treatment personalization: additional confirmation on independent cohorts is warranted.

Molecular and Kinetic Analyses of Circulating Tumor Cells as Predictive Markers of Treatment Response in Locally Advanced Rectal Cancer Patients

Neoadjuvant chemoradiation (NCRT) followed by total mesorectal excision is the standard treatment for locally advanced rectal cancer (LARC). To justify a non-surgical approach, identification of pathologic complete response (pCR) is required. Analysis of circulating tumor cells (CTCs) can be used to evaluate pCR. We hypothesize that monitoring of thymidylate synthase (TYMS) and excision repair protein, RAD23 homolog B (RAD23B), can be used to predict resistance to chemotherapy/radiotherapy. Therefore, the aims of this study were to analyze CTCs from patients with LARC who underwent NCRT plus surgery for expression of TYMS/RAD23B and to evaluate their predictive value. Blood samples from 30 patients were collected prior to NCRT (S1) and prior to surgery (S2). CTCs were isolated and quantified by ISET^®, proteins were analyzed by immunocytochemistry, and TYMS mRNA was detected by chromogenic in situ hybridization. CTC counts decreased between S1 and S2 in patients exhibiting pCR (p = 0.02) or partial response (p = 0.01). Regarding protein expression, TYMS was absent in 100% of CTCs from patients with pCR (p = 0.001) yet was expressed in 83% of non-responders at S2 (p < 0.001). Meanwhile, RAD23B was expressed in CTCs from 75% of non-responders at S1 (p = 0.01) and in 100% of non-responders at S2 (p = 0.001). Surprisingly, 100% of non-responders expressed TYMS mRNA at both timepoints (p = 0.001). In addition, TYMS/RAD23B was not detected in the CTCs of patients exhibiting pCR (p = 0.001). We found 83.3% of sensitivity for TYMS mRNA at S1 (p = 0.001) and 100% for TYMS (p = 0.064) and RAD23B (p = 0.01) protein expression at S2. Thus, TYMS mRNA and/or TYMS/RAD23B expression in CTCs, as well as CTC kinetics, have the potential to predict non-response to NCRT and avoid unnecessary radical surgery for LARC patients with pCR.

Circulating Biomarkers for Response Prediction of Rectal Cancer to Neoadjuvant Chemoradiotherapy

Rectal cancer response to neoadjuvant Chemoradiotherapy (pCRT) is highly variable. In fact, it has been estimated that only about 21 % of patients show pathologic Complete Response (pCR) after therapy, while in most of the patients a partial or incomplete tumour regression is observed. Consequently, patients with a priori chemoradioresistant tumour should not receive the treatment, which is associated with substantial adverse effects and does not guarantee any clinical benefit. For Locally Advanced Rectal Cancer Patients (LARC), a standardized neoadjuvant treatment protocol is applied, the identification and the usefulness of prognostic or predictive biomarkers can improve the antitumoural treatment strategy, modifying the sequence, dose, and combination of radiotherapy, chemotherapy and surgical resection. For these reasons, a growing number of studies are actually focussed on the discovery and investigation of new predictive biomarkers of response to pCRT. In this review, we have selected the most recent literature (2012-2017) regarding the employment of blood-based biomarkers potentially predicting pCR in LARC patients and we have critically discussed them to highlight their real clinical benefit and the current limitations of the proposed methodological approaches.

Recent advances of neoadjuvant chemoradiotherapy in rectal cancer: Future treatment perspectives

Neoadjuvant chemoradiotherapy (nCRT) has been widely used as a multidisciplinary approach for stage II/III rectal cancer. However, its safety and efficacy are controversial because previous studies have shown conflicting outcomes. The present review aimed to elucidate the benefits and limitations of nCRT for patients with rectal cancer. Future perspectives of nCRT are also described. No recent randomized trials have been able to show a survival benefit, although many studies have demonstrated good local control with the use of fluoropyrimidine (e.g. 5-fluorouracil [FU] or capecitabine)-based nCRT. Addition of oxaliplatin (OX) to FU-based nCRT might improve overall survival by preventing distant metastasis, as shown in recent meta-analyses. However, control of adverse effects is an important concern with this treatment. New treatment strategies such as nonoperative management (watch and wait policy) and total neoadjuvant therapy (TNT) are promising, but the establishment of reliable diagnostic methods of metastasis is essential. Development of new biomarkers is also necessary to select patients who are more likely to benefit from nCRT.

Higher nuclear EGFR expression is a better predictor of survival in rectal cancer patients following neoadjuvant chemoradiotherapy than cytoplasmic EGFR expression

The aim of the present study was to investigate the prognostic value of cytoplasmic (−C) and nuclear epidermal growth factor receptor (EGFR-N) expression in rectal cancer patients following neoadjuvant concurrent chemoradiotherapy (CCRT). A total of 172 newly diagnosed rectal cancer patients post-neoadjuvant CCRT and curative surgery, treated between January 1998 to December 2008, were included. Pathological tissues used for evaluation were biopsy specimens obtained prior to CCRT, and specimens collected at surgery. EGFR expression in the nucleus and cytoplasm was assessed by immunohistochemistry tests. An intensity of 3+ EGFR reactivity in the cytoplasm (and/or membrane) of tumor cells was defined as overexpression of EGFR-C. The cutoff percentage of immunoreactive tumor cells for EGFR-N overexpression was 50%. Expression levels of EGFR-C and EGFR-N were further analyzed by clinicopathological features for 5-year survival disease-specific survival (DSS), local recurrence-free survival (LRFS) and metastasis-free survival (MeFS). The results revealed that 20.9 and 23.3% of the cohort had high EGFR-N and EGFR-C expression, respectively. EGFR-N overexpression was significantly associated with advanced pre-treatment tumor stage (T3 and 4; P=0.017) and post-treatment tumor stage (T3 and 4; P<0.001). In univariate analysis, EGFR-N overexpression was significantly associated with poorer DSS (P=0.0005), MeFS (P=0.0182), and LRFS (P=0.0014). Furthermore, it remained an independent prognosticator of worse DSS [P=0.007, hazard ratio (HR)=2.755] and LRFS (P=0.0164, HR=3.026) in multivariate analysis. Overexpression of EGFR-N, and not EGFR-C, may help identify rectal cancer patients who have an increased risk of local recurrence and poor survival following neoadjuvant CCRT.

Systematic review of treatment intensification using novel agents for chemoradiotherapy in rectal cancer

BACKGROUND

With the well established shift to neoadjuvant treatment for locally advanced rectal cancer, there is increasing focus on the use of radiosensitizers to improve the efficacy and tolerability of radiotherapy. There currently exist few randomized data exploring novel radiosensitizers to improve response and it is unclear what the clinical endpoints of such trials should be.

METHODS

A qualitative systematic review was performed according to the PRISMA guidelines using preset search criteria across the PubMed, Cochrane and Scopus databases from 1990 to 2017. Additional results were generated from the reference lists of included papers.

RESULTS

A total of 123 papers were identified, of which 37 were included; a further 60 articles were obtained from additional referencing to give a total of 97 articles. Neoadjuvant radiosensitization for locally advanced rectal cancer using fluoropyrimidine-based chemotherapy remains the standard of treatment. The oral derivative capecitabine has practical advantages over 5-fluorouracil, with equal efficacy, but the addition of a second chemotherapeutic agent has yet to show a consistent significant efficacy benefit in randomized clinical assessment. Preclinical and early-phase trials are progressing with promising novel agents, such as small molecular inhibitors and nanoparticles.

CONCLUSION

Despite extensive research and promising preclinical studies, a definite further agent in addition to fluoropyrimidines that consistently improves response rate has yet to be found.

Genetic variations using whole-exome sequencing might predict response for neoadjuvant chemoradiotherapy in locally advanced rectal cancer

A good pathologic response to neoadjuvant chemoradiotherapy (CRT) in locally advanced rectal cancer (LARC) is associated with a better prognosis. However, there is no effective method to predict CRT response in LARC patients. Therefore, this study used whole-exome sequencing (WES) to identify novel biomarker predicting CRT benefit in LARC. Two independent tumor tissue sets were used to evaluate the genetic differences between the good CRT response group (15 patients achieved a pathologic complete response (pCR)) and the poor CRT response group (15 patients with pathologic stage III). After applying WES to the discovery set of 30 patients, additional samples (n = 67) were genotyped for candidate variants using TaqMan or Sanger sequencing for validation. Overall, this study included a total of 97 LARC patients. In the discovery and validation set, there was no known genetic mutation to predict response between two groups, while five candidate variants (BCL2L10 rs2231292, DLC1 rs3816748, DNAH14 rs3105571, ITIH5 rs3824658, and RAET1L rs912565) were found to be significantly associated with pCR. In the dominant model, the GC/CC genotype of DLC1 rs3816748 (p = 0.032), AC/CC genotype of DNAH14 rs3105571 (p = 0.009), and TT genotype of RAET1 rs912565 (p < 0.0001) were associated with a higher pCR rate. In the recessive model, BCL2L10 rs2231292 (p = 0.036) and ITIH5 rs3824658 (p = 0.003) were significantly associated with pCR. In the co-dominant model, 4 candidate variants (DLC1 rs3816748, DNAH14 rs3105571, ITIH5 rs3824658, and RAET1L rs912565) were significantly correlated with pCR. However, none of the candidate variants was associated with relapse-free or overall survival. The present results suggest that genetic variations of the BCL2L10 rs2231292, DLC1 rs3816748, DNAH14 rs3105571, ITIH5 rs3824658, and RAET1L rs912565 genes can be used as biomarkers predicting the CRT response for patients with LARC.

Associations of Genetic Variations in MicroRNA Seed Regions With Acute Adverse Events and Survival in Patients With Rectal Cancer Receiving Postoperative Chemoradiation Therapy

PURPOSE

The aim of this study was to investigate the associations between single nucleotide polymorphisms (SNPs) in the seed regions of microRNAs and acute adverse events (AEs) and survival in patients with rectal cancer receiving postoperative chemoradiation therapy.

METHODS AND MATERIALS

Eighteen SNPs were genotyped in 365 patients with rectal cancer receiving postoperative chemoradiation therapy. The associations between genotypes and AEs were estimated by odds ratios and 95% confidence intervals (CIs), which were computed by using multivariate logistic regression models. The hazard ratios and 95% CIs to assess the death of patients for different genotypes were calculated by Cox proportional regression models. Overall survival and disease-free survival of patients with different genotypes were estimated by Kaplan-Meier plots, and the statistical significance was determined by using the log-rank test.

RESULTS

In these patients, the most common grade ≥2 AEs were diarrhea (44.1%), leukopenia (29.6%), and dermatitis (18.9%). With false discovery rate correction, SNP rs2273626 was significantly associated with a decreased risk of grade ≥2 leukopenia (odds ratio, 0.48; 95% CI, 0.31-0.74; P = .0009). In addition, SNP rs202195689 was associated with overall survival and disease-free survival in patients receiving postoperative chemoradiation therapy, with the hazard ratios for death being 2.02 (95% CI, 1.36-3.01; P = .0006) and 1.91 (95% CI, 1.36-2.70; P = .0002), respectively. However, no significant association between these SNPs and diarrhea and dermatitis was observed.

CONCLUSIONS

These results suggest that rs2273626 and rs202195689 in microRNA seed regions might serve as independent biomarkers for predicting AEs and prognosis in patients with rectal cancer receiving postoperative chemoradiation therapy. Independent replication of these findings is required to confirm these results.

Protein phosphatase 2A (PP2A) inhibitor CIP2A indicates resistance to radiotherapy in rectal cancer

Preoperative (chemo)radiotherapy, (C)RT, is an essential part of the treatment of rectal cancer patients, but tumor response to this therapy among patients is variable. Thus far, there are no clinical biomarkers that could be used to predict response to (C)RT or to stratify patients into different preoperative treatment groups according to their prognosis. Overexpression of cancerous inhibitor of protein phosphatase 2A (CIP2A) has been demonstrated in several cancers and is frequently associated with reduced survival. Recently, high CIP2A expression has also been indicated to contribute to radioresistance in head and neck squamous cell carcinoma, but few studies have examined the connection between CIP2A and radiation response regarding other malignancies. We have evaluated CIP2A protein expression levels in relation to tumor regression after preoperative (C)RT and survival of rectal adenocarcinoma patients. The effects of CIP2A knockdown by siRNA on cell survival were further investigated in colorectal cancer cells exposed to radiation. Patients with low‐CIP2A‐expressing tumors had more frequently moderate or excellent response to long‐course (C)RT than patients with high‐CIP2A‐expressing tumors. They also had higher 36‐month disease‐specific survival (DSS) rate in categorical analysis. In the multivariate analysis, low CIP2A expression level remained as an independent predictive factor for increased DSS. Suppression of CIP2A transcription by siRNA was found to sensitize colorectal cancer cells to irradiation and decrease their survival in vitro. In conclusion, these results suggest that by contributing to radiosensitivity of cancer cells, low CIP2A protein expression level associates with a favorable response to long‐course (C)RT in rectal cancer patients.

Preoperative chemoradiotherapy for rectal cancer: the sensitizer role of the association between miR-375 and c-Myc

Administration of chemoradiation before tumor resection has revolutionized the management of locally advanced rectal cancer, but many patients have proven resistant to this preoperative therapy. Our group recently reported a negative correlation between c-Myc gene expression and this resistance. In the present study, integrated analysis of miRNA and mRNA expression profiles was conducted in 45 pre-treatment rectal tumors in order to analyze the expressions of miRNAs and c-Myc and their relationship with clinicopathological factors and patient survival. Twelve miRNAs were found to be differentially expressed by responders and non-responders to the chemoradiation. Functional classification revealed an association between the differentially expressed miRNAs and c-Myc. Quantitative real-time PCR results showed that miRNA-148 and miRNA-375 levels were both significantly lower in responders than in non-responders. Notably, a significant negative correlation was found between miRNA-375 expression and c-Myc expression. According to these findings, miRNA-375 and its targeted c-Myc may be useful as a predictive biomarker of the response to neoadjuvant treatment in patients with locally advanced rectal cancer.

High-Dose-Rate Brachytherapy in the Management of Operable Rectal Cancer: A Systematic Review

PURPOSE

To evaluate the role of high-dose-rate endorectal brachytherapy (HDREBT) in the preoperative and definitive management of operable rectal cancer in terms of clinical outcomes and toxicities using a systematic review.

METHODS AND MATERIALS

A review of published articles from January 1990 to December 2016 was conducted using the PubMed, Embase, and Scopus databases using the search terms "rectal" or "rectum" in combination with "brachytherapy," "high dose rate," "HDR," and "endorectal." Additional publications were identified by scanning references. Only studies published in English reporting clinical outcomes with ≥30 patients treated with HDREBT were included.

RESULTS

The search identified 1688 articles, of which 22 met our inclusion criteria. Twelve studies were included in this systematic review. Following preoperative HDREBT with chemoradiation therapy (CRT), the pathologic complete response (pCR) rate ranged between 18% and 31% (weighted mean rate, 22.2%); R0 resection rate, between 80% and 99% (weighted mean rate, 95.5%); and sphincter-preservation rate, between 29% and 54% (weighted mean rate, 46.4%). The weighted mean 2-year progression-free survival and overall survival (OS) rates were 68.1% and 81.5%, respectively. After preoperative HDREBT alone, the pCR rate ranged between 10.4% and 27% (weighted mean rate, 23.8%), the R0 rate was 96.5% (1 study), and the sphincter-preservation rate ranged between 53.8% and 75.8% (weighted mean rate, 59.4%). The weighted mean 5-year progression-free survival and OS rates were 66.6% and 70.8%, respectively. There was only 1 study of HDREBT for nonsurgical management of rectal cancer, which reported a 2-year OS rate of 100%.

CONCLUSIONS

Preoperative HDREBT either alone or in combination with CRT may result in a better pCR but may not necessarily translate into better survival, which is similar to outcomes seen following preoperative CRT alone. There were significant variations across studies in terms of patient selection, treatment approaches, and evaluation of clinical outcomes, suggesting the need for an international consensus on the dosimetric parameters and techniques of HDREBT, timing and methods of response assessment, definitions and assessment of toxicities, and optimal timing of surgery before further prospective studies. Future studies should include evaluation of the role of HDREBT in the nonsurgical curative treatment of screen-detected early cancers and organ preservation in lower rectal cancers.

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.

Pre-treatment platelet counts as a prognostic and predictive factor in stage II and III rectal adenocarcinoma

AIM

To investigate if pre-treatment platelet counts could provide prognostic information in patients with rectal adenocarcinoma that received neo-adjuvant treatment.

METHODS

Platelet number on diagnosis of stage II and III rectal cancer was evaluated in 51 patients receiving neo-adjuvant treatment and for whom there were complete follow-up data on progression and survival, as well as pathologic outcome at the time of surgery. Pathologic responses on the surgical specimen of patients with lower platelet counts (150-300 × 10⁹/L) were compared with these of patients with higher platelet counts (> 300 × 10⁹/L) by the χ² test. Overall and progression free survival Kaplan-Meier curves of the two groups were constructed and compared with the Log-Rank test.

RESULTS

A significant difference was present between the two groups in regards to pathologic response with patients with lower platelet counts being more likely to exhibit a good or complete response to neo-adjuvant treatment than patients with higher platelet counts (P = 0.015). Among other factors evaluated, there was also a significant difference between the carcinoembryonic antigen (CEA) at presentation of patients that exhibited a good or complete response and those that had no response or a minimal to moderate response. Patients with a good or complete response were more likely to present with a CEA of less than 5 μg/L (P = 0.00066). There was no significant difference in overall and progression free survival between the two platelet count groups (Log-Rank tests P = 0.42 and P = 0.35, respectively).

CONCLUSION

In this retrospective analysis of stage II and III rectal cancer patients, platelet counts at the time of diagnosis had prognostic value for neo-adjuvant treatment pathologic response. Pre-treatment CEA also held prognostic value in regards to treatment effect.

miR-17-92a-1 cluster host gene (MIR17HG) evaluation and response to neoadjuvant chemoradiotherapy in rectal cancer

Neoadjuvant chemoradiotherapy (NCRT) followed by surgery is the gold standard for the treatment of patients with locally advanced rectal cancer (LARC). However, response is variable, and no predictive markers have been validated. The amplification of 13q31-34 seemed to distinguish between nonresponders and responders to NCRT. The miR-17-92a-1 cluster host gene (MIR17HG), which is involved in the development, progression, and aggressiveness of colorectal cancer, and the ABCC4 gene, an ATP-binding cassette transporter, are located at this region. Moreover, the transcription factor c-Myc is closely related to MIR17HG. The aim of this study was to examine the role of MIR17HG, ABCC4, and CMYC gene copy numbers (CNs) in determining response to NCRT. We analyzed DNA CN of pretherapy biopsies from 108 LARC patients and the expression of microRNA (miR)-17, miR-18a, miR-19a, miR-19b-1, miR-20a, and miR-92a-1 in 34 biopsies. MIR17HG, CMYC, and ABCC4 gene CNs were frequently altered in pretreatment tumors, amplification being the most frequent alteration. With regard to response to therapy, 41% of responders showed MIR17HG deletion, while MIR17HG amplification was observed in 41% of nonresponders. With regard to pathological T stage (ypT), a higher percentage of ypT3-4 than ypT0-2 tumors showed MIR17HG amplification. Finally, a higher, albeit nonsignificant, variability in the expression of MIR17HG cluster members was detected in nonresponders compared to responders. No association was observed between clinical pathological parameters and ABCC4 or CMYC CN. Our data did not highlight a significant association between MIR17HG, CMYC, and ABCC4 gene CNs and response to NCRT in LARC. However, MIR17HG gene amplification would seem to be related to a lack of response. Evaluation of the expression of MIR17HG cluster members is warranted in a larger case series, together with functional studies, to evaluate the potential of this gene as a new predictive marker.

Predictive value of blood lipid association with response to neoadjuvant chemoradiotherapy in colorectal cancer

The aim of this research was to explore whether blood lipid parameters could predict tumor regression grading (TRG) and compare with the predictive value of carcinoembryonic antigen (CEA) in patients with locally advanced colorectal cancer (LARC) treated with neoadjuvant chemoradiotherapy (nCRT). Between June 2011 and January 2015, the records of 176 patients with primary colorectal adenocarcinoma treated with nCRT followed by radical surgery were reviewed retrospectively. Total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), high-density lipoprotein (HDL), and pre-CEA were measured before nCRT, and post-CEA was measured before surgery. A total of 129 (73.3 %) good responders (TRG 3-4) and 47 (26.7 %) poor responders (TRG 0-2) were assessed after the nCRT. TC, LDL, HDL, and ΔCEA were 6.56 ± 0.95, 3.08 ± 0.72, and 1.43 ± 0.25 mmol/L and -0.69 ± 8.33 μg/mL in poor responders compared with 5.15 ± 1.29, 2.39 ± 0.5, and 1.37 ± 0.32 mmol/L and 16.67 ± 30.18 μg/mL in good responders, respectively (p < 0.05). TG, pre-CEA, and post-CEA were not significantly different. Multivariate logistic regression analysis revealed TC and ΔCEA as independent factors in predicting TRG; TC showed a sensitivity of 62.79 %, a specificity of 91.49 %, a Youden index of 0.543, a cutoff value of 5.52, and an AUC of 0.800 compared with ΔCEA (sensitivity 76.74 %, specificity 65.96 %, Youden index 0.427, and AUC 0.761). TC has a better predictive value than ΔCEA and hence might serve as a predictor of TRG in LARC patients.