Neoadjuvant treatment of rectal cancer: where are we now?

Tumor Immune Microenvironment Biomarkers for Recurrence Prediction in Locally Advanced Rectal Cancer Patients after Neoadjuvant Chemoradiotherapy

BACKGROUND/OBJECTIVES

The tumor microenvironment (TME) has emerged as a significant prognostic factor. This study aimed to identify prognostic factors by combining clinicopathologic parameters and the TME biomarkers in patients who underwent surgery following neoadjuvant chemoradiotherapy (nCRT) for locally advanced rectal cancer (LARC).

METHODS

CD8+ T cells, CXCR3, CXCL10, and α-smooth muscle actin (α-SMA) were analyzed via immunohistochemical staining. We also incorporated AI-powered digital pathology to assess the spatial TME. The associations between these biomarkers, clinicopathologic parameters, and survival outcomes were evaluated.

RESULTS

CD8+ T cell expression, CXCR3 expression in tumor-infiltrating lymphocytes (TILs), and immune phenotypes were correlated. LARC patients with a high expression of CD8+ T cells, CXCR3 in TILs, and an inflamed phenotype had a significantly better prognosis than their counterparts did. In the multivariate analysis, the expression of CD8+ T cells and the inflamed/immune-excluded phenotype were significant tumor immune microenvironment (TiME) biomarkers for recurrence-free survival (RFS) but not for overall survival (OS). Notably, patients with the immune-desert phenotype had a poor prognosis regardless of pathologic stage, even if postoperative chemotherapy was administered (p < 0.001).

CONCLUSIONS

CD8+ T cells and AI-powered immune phenotypes, alongside clinical factors, can guide personalized treatment in LARC patients receiving nCRT. A therapeutic strategy to modify the TiME after nCRT could help reduce recurrence after surgery.

Novel regimens and treatment strategies in neoadjuvant therapy for colorectal cancer: A systematic review

Objective

The objective of this systematic review was to describe novel regimens and treatment strategies in neoadjuvant therapy for colorectal cancer (CRC). The aim was to summarize the current advancements in neoadjuvant chemotherapy (NACT) for CRC, including the use of cytotoxic drugs, targeted treatments, and immunotherapy. The analysis aimed to provide insights into the potential benefits and drawbacks of these novel approaches and highlight the need for further research to optimize NACT use in CRC and improve patient outcomes.

Methods

From October 20, 2023, to December 10, 2023, a comprehensive literature search was conducted across multiple databases, including PubMed, Ovid, Web of Science, the Cochrane Library, Cumulative Index to Nursing and Allied Health Literature, Embase, and Scopus. Studies addressing the use of and treatment strategies for CRC and neoadjuvant therapies were included. Screening was conducted in two steps, initially by title and abstract and then by full-text articles. English-language articles were considered, while preprints, non-English publications, and articles published as grey literature were excluded from the study. A total of 85 studies were selected for further analysis after screening and filtering.

Results

After filtering out duplicates and items that were irrelevant to our research query from the initial database search's 510 results, 397 unique articles were found. Eighty-five studies were chosen for additional analysis after the articles underwent two rounds of screening.

Conclusion

The review concluded that neoadjuvant therapy for CRC has evolved beyond conventional approaches and holds promise for improving patient outcomes. Future prospects for advancing neoadjuvant approaches are promising, with ongoing clinical trials investigating the refinement of strategies, identification of predictive biomarkers, and optimization of patient selection. The adoption of novel regimens, precision medicine, and immunotherapy offers opportunities to redefine treatment paradigms and enhance patient care in CRC.

Predictive effect of the systemic inflammation response index (SIRI) on the efficacy and prognosis of neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer

BACKGROUND

Inflammation is a part of tumours, and inflammatory cells can affect the proliferation, invasion, and development of tumour cells. An increasing number of peripheral blood inflammatory markers have been found to play very important roles in the treatment and prognosis of cancer patients. The systemic inflammatory response index (SIRI) is a newer inflammatory marker, and its role in colorectal cancer, especially in locally advanced rectal cancer, is still unclear.

METHODS

From 2015 to 2020, 198 patients with locally advanced rectal cancer (LARC) who underwent surgery following neoadjuvant chemoradiotherapy (Neo-CRT) were analysed. Patients were categorized into good- and poor- response groups according to their pathological results, and clinical characteristics and baseline parameters were compared between the two groups. The optimal cutoff values for inflammatory indicators were determined using receiver operating characteristic (ROC) analysis. Univariate and multivariate analyses were performed using the Cox proportional hazard model. Survival analysis was performed via the Kaplan‒Meier method.

RESULTS

After patients were grouped into good and poor response groups, indicator differences were found in CEA, neutrophil-to-lymphocyte ratio (NLR), systemic immune-inflammation index (SII), and SIRI. According to the ROC analysis, the NLR (P = 0.015), SII (P = 0.001), and SIRI (P = 0.029) were significant prognostic factors. After univariate and multivariate analyses of the Cox proportional hazards regression model, only the SIRI was found to be an independent prognostic factor for overall survival (OS) and disease-free survival (DFS). Finally, Kaplan‒Meier survival curves also confirmed the ability of the SIRI to predict survival.

CONCLUSION

The preoperative SIRI can be used to predict the response to Neo-CRT in LARC patients and is an independent predictor of OS and DFS in postoperative patients. A high SIRI was associated with poor radiotherapy response and predicted poor OS and DFS.

Trends in rectal cancer incidence, relative survival, and mortality in Denmark during 1978-2018

OBJECTIVE

Rectal cancer is common in developed countries, though incidence varies globally. We assessed time trends in incidence, relative survival and mortality in Denmark.

METHODS

Rectal cancer cases ( N  = 50 461) diagnosed in 1978-2018 were identified in the Danish Cancer Registry. We calculated age-standardized incidence rates, overall and according to sex and age. Average annual percentage changes (AAPC) were estimated using Poisson regression. We estimated 5-year relative survival and evaluated the effect of age, calendar year of diagnosis, sex and stage of disease on mortality using the Cox proportional hazards model.

RESULTS

The incidence of rectal cancer tended to decrease in all age groups and both sexes during 1978-1997, but increased since 1998, more in men (AAPC = 2.05%; 95% CI,1.80; 2.31) than in women (AAPC = 0.99%; 95% CI,0.68; 1.30). It increased in men until 79 years and in women up to 59 years. Mortality decreased over time when adjusting for age, stage and sex. Overall, men had the highest 5-year mortality after adjusting for age, calendar period and stage. Five-year relative survival improved (1978-2018) for all stages. Initially, the overall 5-year relative survival tended to be better for women, but in recent years, it has been similar in both sexes.

CONCLUSION

Incidence of rectal cancer increased in the last two decades, most markedly in women 59 years and younger. Mortality decreased when adjusting for age and stage. Relative survival improved over time more for men than for women, so in recent years, it has been virtually identical in men and women.

Circulating miRNA Signature Predicts Response to Preoperative Chemoradiotherapy in Locally Advanced Rectal Cancer

Patients with locally advanced rectal cancer (LARC) are recommended to receive preoperative chemoradiotherapy (PCRT) followed by surgery. Response to PCRT varies widely: 60%-70% of patients with LARC do not derive therapeutic benefit from PCRT, whereas 15%-20% of patients achieve pathologic complete response (pCR). We sought to develop a liquid biopsy assay for identifying response to PCRT in patients with LARC.

MATERIALS AND METHODS

We analyzed two genome-wide microRNA (miRNA) expression profiling data sets from tumor tissue samples for in silico discovery (GSE68204) and validation (GSE29298). We prioritized biomarkers in pretreatment plasma specimens from clinical training (n = 41; 15 responders and 26 nonresponders) and validation (n = 65; 29 responders and 36 nonresponders) cohorts of patients with LARC. We developed an integrated miRNA panel and established a risk assessment model, which was combined with the miRNA panel and carcinoembryonic antigen levels.

RESULTS

Our comprehensive discovery effort identified an 8-miRNA panel that robustly predicted response to PCRT, with an excellent accuracy in the discovery (area under the curve [AUC] = 0.95) and validation (AUC = 0.92) cohorts. We successfully established a circulating miRNA panel with remarkable diagnostic accuracy in the clinical training (AUC = 0.82) and validation (AUC = 0.81) cohorts. Moreover, the predictive accuracy of the panel was significantly superior to conventional clinical factors in both cohorts (P < .01) and the risk assessment model was superior (AUC = 0.83). Finally, we applied our model to detect patients with pathologic complete response and showed that it was dramatically superior to currently used pathologic features (AUC = 0.92).

CONCLUSION

Our novel risk assessment signature for predicting response to PCRT has a potential for clinical translation as a liquid biopsy assay in patients with LARC.

Mucinous Adenocarcinoma Predicts Poor Response and Prognosis in Patients With Locally Advanced Rectal Cancer: A Pooled Analysis of Individual Participant Data From 3 Prospective Studies

PURPOSE

To evaluate the predictive implications and prognosis of mucinous adenocarcinoma (MAC) in locally advanced rectal cancer (LARC) with intensified neoadjuvant treatment.

METHODS

Individual patient data of LARC patients from 3 prospective clinical trials was analyzed. Neoadjuvant treatment regimens comprised chemoradiotherapy (CRT) with fluorouracil (5-FU) or mFOLFOX6, neoadjuvant chemotherapy alone with mFOLFOX6 or mFOLFOXIRI. The postoperative pathological result, local recurrence and disease-free survival (DFS) were retrospectively analyzed in patients with MAC and adenocarcinoma (AC) with neoadjuvant treatment.

RESULTS

Totally, 743 patients were recruited, with 620 patients eligible for analysis. Fifty-three (8.5%) patients were MAC. The pathological complete response (pCR) rate and tumor downstaging rate (ypStage 0-I) between MAC and AC patients was 7.5% vs. 22.0% (P = .01) and 20.8% vs. 48.7% (P < .001), respectively. Among patients receiving preoperative CRT with 5FU or mFOLFOX6, the pCR rate and tumor downstaging rate between MAC and AC patients was 11.1% vs. 27.3% (P = .03) and 23.7% vs. 52.6% (P = .001), respectively. Regarding neoadjuvant chemotherapy alone with mFOLFOX6 or mFOLFOXIRI, the pCR rate and tumor downstaging rate was 0 vs.13.2% (P = .11) and 11.8% vs. 42.5% (P = .03) between MAC and AC group, respectively. With the median follow-up time of 38.9 months, the 3-year DFS and 3-year locoregional recurrence rate was 58.4% vs. 77.6% (P = .02) and 26.0% vs. 5.7% (P = .001) in the MAC and AC group, respectively. MAC (hazard ratio [HR] 1.85, 95% confidence interval [CI], 1.15-2.98), PNI (HR 3.23, 95% CI, 1.85-5.72) and LVI (HR 2.04, 95% CI, 1.02-4.08) were independent prognosis factors and were associated with worse DFS.

CONCLUSIONS

Patients with MAC of the rectum are associated with a lower pCR rate and tumor downstaging rate, higher incidence of local recurrence, and poorer DFS with neoadjuvant treatment.

Can pretreatment blood biomarkers predict pathological response to neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer?

Aims: To investigate the value of previously described pretreatment hematological and biochemical biomarkers as predictors of pathological response. Methods: The authors performed a retrospective analysis of 191 patients with locally advanced rectal cancer who underwent long-course neoadjuvant chemoradiotherapy at two Portuguese centers. The authors performed logistic regression analysis to search for predictive markers of pathological complete and good response. Results: High platelet-neutrophil index (p = 0.042) and clinical tumor stage >2 (p = 0.015) were predictive of poor response. None of the analyzed biomarkers predicted pathological complete response in this study. Conclusion: A high platelet-neutrophil index before neoadjuvant chemoradiotherapy could help predict poorer pathological response in patients with locally advanced rectal cancer. However, no other blood biomarker predicted incomplete or poor response in this study.

Pathological response post neoadjuvant therapy for locally advanced rectal cancer is an independent predictor of survival

AIM

Neoadjuvant treatment (NaT) for locally advanced rectal cancer prior to surgery has led to improved outcomes. However, the relationship between pathological response to NaT and survival is not entirely clear. The aim of this study was to assess the degree of pathological response to NaT on survival outcomes.

METHODS

Clinical and pathological data were collected from a prospectively maintained pathology database between 2005 and 2017. The primary outcome was the overall survival based on pathological response categorized as complete, good partial, partial and minimal. Univariate and multivariate analyses were conducted to identify variables predictive of survival. Cox proportional hazard ratios were used for survival.

RESULTS

A total of 596 patients had surgery following NaT for locally advanced rectal cancer. The median follow-up was 4.57 years (interquartile range 2.21-8.15 years). The overall survival for complete pathological response was 75.6% vs. 37.3% for minimal response (P < 0.001). The overall survival at the end of the study in the good partial vs. partial response groups was 58.9% vs. 39% (P < 0.001). On multivariate analysis, the degree of pathological response remains an independent variable for overall and disease-specific survival across all categories.

DISCUSSION

In addition to other pathological variables, the degree of pathological response to NaT is an independent predictor for survival outcomes. Future verification of these findings elsewhere could support NaT response being used for adjuvant therapy decision making.

CEA Decline Predicts Tumor Regression and Prognosis in Locally Advanced Rectal Cancer Patients with Elevated Baseline CEA

Purpose: To investigate the value of carcinoembryonic antigen (CEA) decline in predicting pathological tumor regression and outcome for locally advanced rectal cancer (LARC) patients who received neoadjuvant therapy with elevated baseline CEA.

Methods: LARC patients with elevated pre-treatment CEA who received neoadjuvant therapy and radical tumor resection were retrospectively collected. Serum CEA level during treatment were recorded and the predictive value of pre-treatment CEA, post-treatment CEA and CEA ratio (CEA^{post-treatment} /CEA^{pre-treatment}) for tumor regression grade (TRG), overall survival and diseases free survival were estimated by logistic regression or cox proportional hazard regression.

Results: Two hundred and eighty-four LARC patients with elevated pre-treatment CEA were enrolled and the baseline, post-treatment CEA level and CEA ratio were 11.87 (5.02-731.31) ng/ml, 4.23 (0.50-173.80) ng/ml and 0.31(0.01-2.55) respectively. CEA level in 59.2% of the patients declined to normal after neoadjuvant therapy. Multivariate analysis showed that CEA ratio was an independent predictor for TRG (OR=3.463, 95% CI: 1.269-9.446, P=0.015) and tumor downstage (OR=0.393, 95% CI: 0.187-0.829, P=0.014). Patients with normalized post-treatment CEA level had better overall survival (P=0.010) and disease free survival (P=0.003) than those with elevated CEA level. Higher post-treatment CEA was an independent unfavored predictor for overall survival in LARC patients with elevated pre-treatment CEA (OR=1.042, 95% CI: 1.017-1.067, P=0.001).

Conclusion: Post/pre-treatment CEA ratio predicted tumor regression in term of TRG and tumor downstage for LARC patients with elevated pre-treatment CEA and higher post-treatment CEA predicted poor overall survival.

Factors influencing recurrence of stage I-III rectal cancer in regional Australia

BACKGROUND

As treatments for rectal cancer improve with developments in surgical techniques, radiotherapy and chemotherapy, the nature of recurrences are evolving. We used a comprehensive database of a large Australian population with stage I-III rectal adenocarcinoma to identify timing and prognostic significance of recurrences, and factors associated with risk of developing recurrent disease.

METHODS

All patients with locoregional rectal cancer treated with curative intent in our health district from 2006 to 2017 were included. Multivariate analysis using Cox regression models were used to identify factors associated with recurrence.

RESULTS

A total of 483 patients were included. Recurrence occurred in 117 (24.2%) of 483 patients, being locoregional in 15 (3.1%) patients, distant in 85 patients (17.6%) and both locoregional and distant in 17 (3.5%) patients. Compared to those with locoregional recurrence, those with both locoregional and distant recurrence had worse cancer-specific survival. On univariate analysis, factors associated with recurrence included stage, grade, radiotherapy, chemotherapy, surgery type and distal tumour location. Factors which remained significant on multivariate analysis included higher grade and stage.

CONCLUSION

In the era of multimodality therapy for rectal cancer, recurrences are predominantly distant. Traditional predictors including higher stage, grade and distal tumour location remain independently associated with recurrence, despite current treatment paradigms.

Model-Based Dose Calculation Algorithms for Brachytherapy Dosimetry

The purpose of this study was to review the limitations of dose calculation formalisms for photon-emitting brachytherapy sources based on the American Association of Physicists in Medicine (AAPM) Task Group No. 43 (TG-43) report and to provide recommendations to transition to model-based dose calculation algorithms. Additionally, an overview of these algorithms and approaches is presented. The influence of tissue and seed/applicator heterogeneities on brachytherapy dose distributions for breast, gynecologic, head and neck, rectum, and prostate cancers as well as eye plaques and electronic brachytherapy treatments were investigated by comparing dose calculations based on the TG-43 formalism and model-based dose calculation algorithms.

Nomogram for predicting pathological complete response and tumor downstaging in patients with locally advanced rectal cancer on the basis of a randomized clinical trial

Background

Preoperative fluoropyrimidine with radiotherapy was regarded as the standard of care for locally advanced rectal cancer (LARC). The model for predicting pCR in LARC patients was based on standard treatment only. This study aimed to establish a nomogram with pretherapeutic parameters and different neoadjuvant regimens for predicting pathologic complete response (pCR) and tumor downstaging or good response (ypT0-2N0M0) after receiving neoadjuvant treatment in patients with LARC based on a randomized clinical trial.

Methods

Between January 2011 and February 2015, 309 patients with rectal cancer were enrolled from a prospective randomized study (NCT01211210). All pretreatment clinical parameters were collected to build a nomogram for predicting pCR and tumor downstaging. The model was subjected to bootstrap internal validation. The predictive performance of the model was assessed with concordance index (C-index) and calibration plots.

Results

Of the 309 patients, 53 (17.2%) achieved pCR and 132 (42.7%) patients were classified as tumor downstaging with ypT0-2N0M0. Based on the logistic-regression analysis and clinical consideration, tumor length (P = 0.005), tumor circumferential extent (P = 0.036), distance from the anal verge (P = 0.019), and neoadjuvant treatment regimen (P < 0.001) showed independent association with pCR following neoadjuvant treatment. The tumor length (P = 0.015), tumor circumferential extent (P = 0.001), distance from the anal verge (P = 0.032), clinical T category (P = 0.012), and neoadjuvant treatment regimen (P = 0.001) were significantly associated with good tumor downstaging (ypT0-2N0M0). Nomograms were developed to predict the probability of pCR and tumor downstaging with a C-index of 0.802 (95% confidential interval [CI], 0.736–0.867) and 0.730 (95% CI, 0.672–0.784). Internal validation revealed good performance of the calibration plots.

Conclusions

The nomogram provided individual prediction responses to different preoperative treatment for patients with rectal cancer. This model might help physicians in selecting an optimized treatment, but warrants further external validation.

Baseline and early 3D-CUBE volume reconstruction of locally advanced rectal cancer to predict tumor response after neoadjuvant chemotherapy

PURPOSE

To explore whether volumetric measurements of 3D-CUBE sequences based on baseline and early treatment time can predict neoadjuvent chemotherapy (NCT) efficacy of locally advanced rectal cancer (LARC).

MATERIAL AND METHOD

73 patients with LARC were enrolled from February 2014 to January 2018. All patients underwent MRIs during the baseline period before NCT (BL-NCT) and the first month of NCT (FM-NCT), and tumor volume (TV) was measured using 3D-CUBE, and tumor volume reduction (TVR) and tumor volume reduction rate (TVRR) were calculated. In addition, tumor invasion depth, tumor maximal length, range of tumor involvement in the circumference of intestinal lumen and distance from inferior part of tumor to the anal verge were measured using baseline high-spatial-resolution T2-weighted MRIs. All patients were categorized into sensitive and insensitive groups based on post-surgical pathology after completion of the full courses of NCT. The receiver operating characteristic (ROC) curve was used to analyze the value of different MRI parameters in predicting efficacy of NCT.

RESULTS

Statistically significant differences in TV of BL-NCT, TVR and TVRR from BL-NCT to FM-NCT were detected between sensitive and insensitive groups (P < 0.05, respectively). The areas under the curves (AUC) of ROC of TVR and TVRR in predicting efficacy of NCT (0.890 [95% CI, 0.795∼0.951], 0.839 [95% CI, 0.735∼0.915]) were significantly better than that of TV (0.660 [95% CI, 0.540∼0.767]) (P < 0.05, respectively).

CONCLUSION

Reconstruction of 3D-CUBE volume in the first month of NCT is necessary, and both TVR and TVRR can be used as early predictors of NCT efficacy.

Preoperative assessment of lymph node metastasis in clinically node-negative rectal cancer patients based on a nomogram consisting of five clinical factors

Background

Currently, reliable approaches for accurate assessment of lymph node metastases (LNM), which is an important indication of preoperative chemoradiotherapy (CRT), are not available for clinically node-negative rectal cancer patients. This study aims to identify clinical factors associated with LNM and to establish a nomogram for LNM prediction in clinically node-negative rectal cancer patients.

Methods

The least absolute shrinkage and selection operator (LASSO) aggression and multivariate logistic regression analyses were applied to identify clinical factors associated with LNM. A nomogram was established to predict the probability of LNM in clinically node-negative rectal cancer patients based on the multivariate logistic regression model.

Results

Six potential risk factors were selected on the basis of LASSO aggression analysis, and five of them were identified as independent risk factors for LNM based on multivariate analysis, including MRI-reported tumor location, clinical T classification, MRI-reported tumor diameter, white blood cell count (WBC), and preoperative elevated tumor markers. A nomogram consisting of the five clinical factors was established and showed good discrimination. Decision curve analysis demonstrated that the established nomogram was reliable and accurate for LNM prediction in clinically node-negative rectal cancer patients.

Conclusions

A nomogram based on five clinical factors, including MRI-reported tumor location, clinical T classification, MRI-reported tumor diameter, WBC, and preoperative elevated tumor markers, are useful for assessing LNM in clinically node-negative rectal cancer patients, which is important for preoperative CRT regimens.

Pretreatment blood biomarkers predict pathologic responses to neo-CRT in patients with locally advanced rectal cancer

Aim: To evaluate the value of pretreatment blood biomarkers in predicting pathologic responses to neoadjuvant chemoradiotherapy (neo-CRT) in patients with locally advanced rectal cancer. Materials & methods: We conducted logistic regression analysis and receiver operating characteristic to assess the predictive value of blood biomarkers. The outcome was defined by the pathologic complete response and good response. Results: Carcinoembryonic antigen (CEA) (p < 0.001), neutrophil-to-lymphocyte ratio (p = 0.024), platelet-to-lymphocyte ratio (p = 0.006) and lymphocyte-to-monocyte ratio (LMR) (p < 0.001) were significant predictors of pathologic complete response, with area under the curve of 0.785, 0.794, 0.740 and 0.913, respectively; CEA (p = 0.007) and LMR (p < 0.001) correlated significantly with good response, with area under the curve of 0.743 and 0.771, respectively. Conclusion: Lower LMR and higher CEA, neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio before treatment could predict poorer pathologic response to neo-CRT in patients with locally advanced rectal cancer.

Neoadjuvant Radiochemotherapy Significantly Alters the Phenotype of Plasmacytoid Dendritic Cells and 6-Sulfo LacNAc+ Monocytes in Rectal Cancer

Neoadjuvant radiochemotherapy (nRCT) can significantly influence the tumor immune architecture that plays a pivotal role in regulating tumor growth. Whereas, various studies have investigated the effect of nRCT on tumor-infiltrating T cells, little is known about its impact on the frequency and activation status of human dendritic cells (DCs). Plasmacytoid DCs (pDCs) essentially contribute to the regulation of innate and adaptive immunity and may profoundly influence tumor progression. Recent studies have revealed that higher pDC numbers are associated with poor prognosis in cancer patients. 6-sulfo LacNAc-expressing monocytes (slanMo) represent a particular proinflammatory subset of human non-classical blood monocytes that can differentiate into DCs. Recently, we have reported that activated slanMo produce various proinflammatory cytokines and efficiently stimulate natural killer cells and T lymphocytes. slanMo were also shown to accumulate in clear cell renal cell carcinoma (ccRCC) and in metastatic lymph nodes from cancer patients. Here, we investigated the influence of nRCT on the frequency of rectal cancer-infiltrating pDCs and slanMo. When evaluating rectal cancer tissues obtained from patients after nRCT, a significantly higher density of pDCs in comparison to pre-nRCT tissue samples was found. In contrast, the density of slanMo was not significantly altered by nRCT. Further studies revealed that nRCT significantly enhances the proportion of rectal cancer-infiltrating CD8⁺ T cells expressing the cytotoxic effector molecule granzyme B. When exploring the impact of nRCT on the phenotype of rectal cancer-infiltrating pDCs and slanMo, we observed that nRCT markedly enhances the percentage of inducible nitric oxide synthase (iNOS)- or tumor necrosis factor (TNF) alpha-producing slanMo. Furthermore, nRCT significantly increased the percentage of mature CD83⁺ pDCs in rectal cancer tissues. Moreover, the proportion of pDCs locally expressing interferon-alpha, which plays a major role in antitumor immunity, was significantly higher in post-nRCT tissues compared to pre-nRCT tumor specimens. These novel findings indicate that nRCT significantly influences the frequency and/or phenotype of pDCs, slanMo, and CD8⁺ T cells, which may influence the clinical response of rectal cancer patients to nRCT.

Nomograms for predicting pathological response to neoadjuvant treatments in patients with rectal cancer

BACKGROUND

In recent decades, neoadjuvant therapy (NT) has been the standardized treatment for locally advanced rectal cancer (LARC). Approximately 8%-35% of patients with LARC who received NT were reported to have achieved a complete pathological response (pCR). If the pathological response (PR) can be accurately predicted, these patients may not need surgery. In addition, no response after NT implies that the tumor is destructive, resistant to both chemotherapy and radiotherapy, and prone to having a high metastatic potential. Therefore, developing accurate models to predict PR has great clinical significance and can help achieve individualized treatment in LARC patients.

AIM

To establish nomograms for predicting PR to different NT regimens based on pretreatment parameters for patients with LARC.

METHODS

Rectal cancer patients were identified from the database of The Sixth Affiliated Hospital, Sun Yat-sen University from January 2012 to December 2016. Logistic regression and nomograms were developed to predict the probability of pCR and good downstaging to ypT0-2N0M0 (ypTNM 0-I), respectively, based on pretreatment parameters for all LARC patients. Nomograms were also developed for three NT regimens (capecitabine/deGramont-RT, mFOLFOX6, and mFOLFOX6-RT) to predict pCR probability.

RESULTS

Four hundred and three patients were included in this study; 72 (17.9%) had pCR at the final pathology report, and 177 (43.9%) achieved good downstaging to ypT0-2N0M0 (ypTNM 0-I). The nomogram for predicting pCR probability showed that NT regimens, tumor differentiation, mesorectal fascia (MRF) status, and tumor length significantly influenced pCR probability. When predicting the probability of good downstaging, tumor differentiation, MRF status, and clinical T stage were the significant factors. Nomograms were developed based on NT regimens. For the capecitabine/de Gramont-RT group, the multivariate analysis showed that the neutrophil-lymphocyte ratio (NLR) was the only significant factor, thus we could not develop a nomogram for this regimen. For the mFOLFOX6-RT group, the analysis showed that the significant factors were tumor length and MRF status; and for the mFOLFOX6 group, the significant factors were tumor length and tumor differentiation.

CONCLUSION

We established accurate nomograms for predicting the PR to preoperative NT regimens based on pretreatment parameters for LARC patients.

Association of tumor differentiation and prognosis in patients with rectal cancer undergoing neoadjuvant chemoradiation therapy

Background and objective

Neoadjuvant chemoradiation therapy (NCRT) followed by radical resection has been a common practice for patients with locally advanced rectal cancer. This study aimed to analyse the association of tumor differentiation and prognosis in rectal-cancer patients undergoing NCRT.

Methods

Patients with locally advanced, non-mucinous rectal cancer who underwent NCRT followed by radical resection between 2007 and 2017 were identified from an electronic health record system at the Sixth Affiliated Hospital of Sun Yat-sen University (Guangzhou, China). Multivariable logistic regression and multivariate Cox regression were performed to analyse the association of response to NCRT and survival with clinicopathological characteristics of all these patients.

Results

We identified 325 patients (241 males and 84 females; mean age, 54.4 ± 11.2 years) who underwent NCRT followed by radical resection, including 26 (8.0%) with poorly-differentiated rectal cancer, 182 (56.0%) with moderately-differentiated cancer and 117 (36.0%) with well differentiated cancer. Propensity score matching analysis and multivariable logistic regression analysis results showed that tumor differentiation was significantly associated with response to NCRT. In the poor differentiation and non-poor differentiation groups, the 3-year overall survival (OS) rates were 74.6 and 93.5%, respectively, whereas the 3-year local recurrence rates were 18.6 and 3.7%, respectively. Multivariable Cox regression analyses revealed that poor differentiation was an independent risk factor for local recurrence and OS.

Conclusions

Among the patients with locally advanced, non-mucinous rectal cancer, the patients with poorly-differentiated cancer who underwent NCRT had a worse response to NCRT and poorer prognosis than those with moderately- and well-differentiated diseases.

Is it Possible to Successfully Treat Locally Advanced Colon Cancer Using Pre-Operative Chemoradiotherapy?

Pre-operative chemoradiotherapy (CRT) is a preferable treatment option for patients with locally advanced rectal cancer. However, few data are available regarding pre-operative CRT for locally advanced colon cancer. Here, we describe two cases of successful treatment with pre-operative CRT and establish evidence supporting this treatment option in patients with locally advanced colon cancer. In the first case, a 65-year-old woman was diagnosed with ascending colon cancer with duodenal invasion. In the second case, a 63-year-old man was diagnosed with a colonic-duodenal fistula due to transverse colon cancer invasion. These case reports will help to establish a treatment consensus for pre-operative CRT in patients with locally advanced colon cancer.

'Watch and wait' in rectal cancer: summary of the current evidence

BACKGROUND

The management of rectal cancer has evolved considerably over the last few decades with increasing use of neoadjuvant chemoradiotherapy (nCRT). Complete clinical response (cCR) and even complete pathological response (pCR) have been noted in a proportion of patients who had surgery after nCRT. This raises the concern that we may have been 'over-treating' some of these patients and lead to an increasing interest in 'watch and wait' (W&W) approach for patients who had cCR to avoid the morbidity associated with rectal surgery.

METHODS

A review of the literature in English pertaining to rectal cancer in the context of W&W, organ preservation and active surveillance.

RESULTS

Evidence available to support W&W approach comes from non-randomised controlled trials (RCTs) with no current consensus on patients' selection criteria, lack of viable predictors of both cCR and pCR and lack of universal definitions of cCR and pCR. Also, there is no agreed protocol for disease surveillance.

CONCLUSION

Even though there has been increasing reports on the outcomes of W&W in rectal cancer, the current evidence cannot support its routine use in clinical practice. This approach should be used in clinical trials settings or after thorough counselling with the patient on the outcomes of various treatment options.

Potential of memory T cells in bridging preoperative chemoradiation and immunotherapy in rectal cancer

The management of locally advanced rectal cancer has passed a long way of developments, where total mesorectal excision and preoperative radiotherapy are crucial to secure clinical outcome. These and other aspects of multidisciplinary strategies are in-depth summarized in the literature, while our mini-review pursues a different goal. From an ethical and medical standpoint, we witness a delayed implementation of novel therapies given the cost/time consuming process of organizing randomized trials that would bridge an already excellent local control in cT3-4 node-positive disease with long-term survival. This unfortunate separation of clinical research and medical care provides a strong motivation to repurpose known pharmaceuticals that suit for treatment intensification with a focus on distant control. In the framework of on-going phase II-III IG/IMRT-SIB trials, we came across an intriguing translational observation that the ratio of circulating (protumor) myeloid-derived suppressor cells to (antitumor) central memory CD8+ T cells is drastically increased, a possible mechanism of tumor immuno-escape and spread. This finding prompts that restoring the CD45RO memory T-cell pool could be a part of integrated adjuvant interventions. Therefore, the immunocorrective potentials of modified IL-2 and the anti-diabetic drug metformin are thoroughly discussed in the context of tumor immunobiology, mTOR pathways and revised Warburg effect.

microRNA-451a regulates colorectal cancer proliferation in response to radiation

BACKGROUND

Colorectal cancer (CRC) is a leading cause of cancer-related death. The biologic response of CRC to standard of care adjuvant therapies such as chemotherapy and radiation are poorly understood. MicroRNAs (miRs) have been shown to affect CRC progression and metastasis. Therefore, we hypothesized that specific miRs modulate CRC response to chemoradiation.

METHODS

In this study, we used miR expression profiling and discovered a set of microRNAs upregulated rapidly in response to either a single 2 Gy dose fraction or a 10 Gy dose of γ-radiation in mouse colorectal carcinoma models. We used gain and loss-of-function studies in 2D and 3Dcell proliferation assays and colony formation assays to understand the role of the top miR candidate from our profiling. We used Student's T-tests for simple comparisons and two-factor ANOVA for evaluating significance.

RESULTS

The most upregulated candidate at early time points in our signature, miR-451a inhibited tumor cell proliferation and attenuated surviving fraction in longer-term cultures. Conversely, inhibition of miR-451a increased proliferation, tumorsphere formation, and surviving fraction of tumor cells. Using a bioinformatics approach, we identified four genes, CAB39, EMSY, MEX3C, and EREG, as targets of miR-451a. Transfection of miR-451a decreased both mRNA and protein levels of these targets. Importantly, we found miR-451a expression was high and CAB39, EMSY levels were low in a small subset of rectal cancer patients who had a partial response to chemoradiation when compared to patients that had no response. Finally, analysis of a TCGA colorectal cancer dataset revealed that CAB39 and EMSY are upregulated at the protein level in a significant number of CRC patients. Higher levels of CAB39 and EMSY correlated with poorer overall survival.

CONCLUSIONS

Taken together, our data indicates miR-451a is induced by radiation and may influence colorectal carcinoma proliferation via CAB39 and EMSY pathways.