Pathological and molecular predictors of the response of rectal cancer to neoadjuvant radiochemotherapy

Predicting pathological response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer with two step feature selection and ensemble learning

Patients with locally advanced rectal cancer (LARC) show substantial individual variability and a pronounced imbalance in response distribution to neoadjuvant chemoradiotherapy (nCRT), posing significant challenges to treatment response prediction. This study aims to identify effective predictive biomarkers and develop an ensemble learning-based prediction model to assess the response of LARC patients to nCRT. A two-step feature selection method was developed to identify predictive biomarkers by deriving stable reversal gene pairs through within-sample relative expression orderings (REOs) from LARC patients undergoing nCRT. Preliminary screening utilized four methods-MDFS, Boruta, MCFS, and VSOLassoBag-to form a candidate feature set. Secondary screening ranked these features by permutation importance, applying Incremental Feature Selection (IFS) with an Extreme Gradient Boosting (XGBoost) to determine final predictive gene pairs. The ensemble model BoostForest, combining boosting and bagging, served as the predictive framework, with SHAP employed for interpretability. Through two-step feature selection, the 32-gene pair signature (32-GPS) was established as the final predictive biomarker. In the test set, the model achieved an area under the precision-recall curve (AUPRC) of 0.983 and an accuracy of 0.988. In the validation cohort, the AUPRC was 0.785, with an accuracy of 0.898, indicating strong model performance. The study further demonstrated that BoostForest achieved superior overall performance compared to Random Forest, Support Vector Machine (SVM), and XGBoost. To evaluate the effectiveness of the 32-GPS, its performance was compared with two alternative feature sets: the lasso-gene pair signature (lasso-GPS), derived through lasso regression, and the 15-shared gene pair signature (15-SGPS), consisting of gene pairs identified by all four feature selection methods. The 32-GPS demonstrated superior performance in both comparisons. The two-step feature selection method identified robust predictive biomarkers, and BoostForest outperformed Random Forest, Support Vector Machine, and XGBoost in classification performance and predictive capability.

Research trends of neoadjuvant therapy in lung cancer: a bibliometric analysis

BACKGROUND

Lung cancer is the most prevalent malignancy worldwide. Only a fraction of early-stage patients undergo radical surgery; however, many still experience recurrence and metastasis within 5 years postoperatively (approximately 30-75%). Neoadjuvant therapy has revolutionized the treatment approach for lung cancer, with a growing number of clinical trials investigating this modality. This study provides a comprehensive analysis of neoadjuvant therapy in lung cancer, intending to guide future research.

METHOD

To extract literature on neoadjuvant therapy for lung cancer published in the Web of Science Core Collection, spanning January 1, 2004, to December 31, 2023. Utilizing software tools including VOSviewer, CiteSpace, and GraphPad Prism to conduct bibliometric analysis and visualization studies on countries, institutions, journals, authors, co-cited references, and keywords in this field.

RESULTS

A sum of 6,085 research publications from 84 countries were analyzed, with the United States leading in publications on neoadjuvant therapy for lung cancer. The institution that publishes the most articles is the University of Texas System. The most published journal is Annals of Thoracic Surgery, while the most frequently co-cited journal is Journal of Clinical Oncology. Eight of the top ten co-cited references concern immune checkpoint inhibitors(ICIs). Keyword burst analysis indicates that the current research focuses and trends mainly center around four areas: ICIs, clinical trials, efficacy, and non-small cell lung cancer (NSCLC).

CONCLUSIONS

This is the first bibliometric study of neoadjuvant therapy in lung cancer. Over the past two decades, interest in this field has steadily increased, particularly since 2017. The United States is the largest contributor and has the highest number of publications in this field. Immune checkpoint inhibitors, clinical trials, efficacy, and NSCLC are hotspots in neoadjuvant therapy for lung cancer, both now and in the foreseeable future.

Active surveillance in long period of total neoadjuvant therapy in rectal cancer: Early prediction of poor regression response

AIM

To analyze locally advanced rectal cancer (LARC) patients and tumor characteristics during the period of total neoadjuvant therapy (TNT) and explore the risk factors that may predict poor tumor regression in response to TNT.

MATERIALS AND METHODS

The data of 120 LARC patients who received TNT from December 2016 and September 2019 in our hospital were retrospectively analyzed. The clinicopathological characteristics of patients with different tumor regression responses were compared. Then we divided patients into two groups according to the carcinoembryonic antigen (CEA) clearance pattern after chemoradiation to explore risk factors that might predict the tumor regression response.

RESULTS

Of 120 LARC patients, 34 (28.3%) exhibited poor regression. Stratified analysis by tumor response showed that patients with poor response to TNT were more likely to obtain elevated CEA during the course of TNT (all P < 0.05). For those with elevated pretreatment CEA, fewer patients with poor response obtained normal CEA after chemoradiation (13.6% vs. 72.7%, P < 0.001). Besides, less patients' CEA levels in the poor response group decreased by greater than 50% after chemoradiation when compared with that in the good response group (18.2% vs. 60.6%, P = 0.002). Stratified analysis by CEA clearance pattern after chemoradiation showed patients who obtained an elevated pretreatment CEA and decreased by less than 50% after chemoradiation were more likely to have poor response to TNT compared to others (76.2% vs. 18.2%, P < 0.001). Logistic multivariate analysis revealed that cN2 (95% CI 1.553-16.448), larger tumors (95% CI 2.250-21.428) and CEA clearance pattern after chemoradiation (95% CI 1.062-66.992) were independent risk factors for poor tumor regression response.

CONCLUSION

Approximately one-fourth of LARC patients with TNT achieved a poor regression response. Here, cN2, larger tumor size before treatment and elevated CEA levels were considered predictive features of a poor response. Active surveillance of CEA levels during the TNT course are potentially important, and CEA levels after chemoradiation might have important implications for the tumor response to TNT.

Rectal Sparing Approach After Neoadjuvant Therapy in Patients with Rectal Cancer: The Preliminary Results of the ReSARCh Trial

BACKGROUND

Rectum-preservation for locally advanced rectal cancer has been proposed as an alternative to total mesorectal excision (TME) in patients with major (mCR) or complete clinical response (cCR) after neoadjuvant therapy. The purpose of this study was to report on the short-term outcomes of ReSARCh (Rectal Sparing Approach after preoperative Radio- and/or Chemotherapy) trial, which is a prospective, multicenter, observational trial that investigated the role of transanal local excision (LE) and watch-and-wait (WW) as integrated approaches after neoadjuvant therapy for rectal cancer.

METHODS

Patients with mid-low rectal cancer who achieved mCR or cCR after neoadjuvant therapy and were fit for major surgery were enrolled. Clinical response was evaluated at 8 and 12 weeks after completion of chemoradiotherapy. Treatment approach, incidence, and reasons for subsequent TME were recorded.

RESULTS

From 2016 to 2019, 160 patients were enrolled; mCR or cCR at 12 weeks was achieved in 64 and 96 of patients, respectively. Overall, 98 patients were managed with LE and 62 with WW. In the LE group, Clavien-Dindo 3+ complications occurred in three patients. The rate of cCR increased from 8- to 12-week restaging. Thirty-three (94.3%) of 35 patients with cCR had ypT0-1 tumor. At a median 24 months follow-up, a tumor regrowth was found in 15 (24.2%) patients undergoing WW.

CONCLUSIONS

LE for patients achieving cCR or mCR is safe. A 12-week interval from chemoradiotherapy completion to LE is correlated with an increased cCR rate. The risk of ypT > is reduced when LE is performed after cCR.

Prognostic Factors and Treatment of Recurrence after Local Excision of Rectal Cancer

PURPOSE

Indications for local excision in patients with rectal cancer remain controversial. We reviewed factors affecting survival rate and treatment effectiveness in cancer recurrence after local excision among patients with rectal cancer.

MATERIALS AND METHODS

A total of 831 patients was enrolled. Of these, 391 patients were diagnosed with primary rectal cancer and underwent local excision. A retrospective observational study was performed on patients who underwent full-thickness local excision for rectal cancer.

RESULTS

The median duration of follow-up was 61 months. The overall recurrence rate was 11.5%. The rate of local recurrence was 5.1%. Five-year overall survival rate among recurrent patients was 66.8%; the rate among patients who underwent salvage operation due to recurrence was 84.7%, compared with 44.2% among patients treated with non-operative management (p<0.001). Multivariate analysis of disease-free survival identified distance from the anal verge (p=0.038) and histologic grade (p=0.047) as factors predicting poor prognosis. Multivariate analysis of overall survival showed that age (p<0.001), serum carcinoembryonic antigen (CEA) levels (p=0.001), and histologic grade (p=0.013) also affected poor prognosis. In subgroup analysis of patients with recurrence, 25 patients underwent reoperation, while 20 patients did not. For 5-year overall survival rate, there was a significant difference between 84.7% of the reoperation group and 44.2% of the non-operation group (p<0.001).

CONCLUSION

The risk factors affecting overall survival rate after local excision were age 65 years or older, preoperative CEA level 5 or higher, and high histologic grade. In cases of recurrence after local excision of rectal cancer, salvage operation might improve overall survival.

Overexpression of MLPH in Rectal Cancer Patients Correlates with a Poorer Response to Preoperative Chemoradiotherapy and Reduced Patient Survival

Data mining of a public transcriptomic rectal cancer dataset (GSE35452) from the Gene Expression Omnibus, National Center for Biotechnology Information identified the melanophilin (MLPH) gene as the most significant intracellular protein transport-related gene (GO:0006886) associated with a poor response to preoperative chemoradiation. An MLPH immunostain was performed on biopsy specimens from 172 rectal cancer patients receiving preoperative chemoradiation; samples were divided into high- and low-expression groups by H-scores. Subsequently, the correlations between MLPH expression and clinicopathologic features, tumor regression grade, disease-specific survival (DSS), local recurrence-free survival (LRFS), and metastasis-free survival (MeFS) were analyzed. MLPH expression was significantly associated with CEA level (p = 0.001), pre-treatment tumor status (p = 0.022), post-treatment tumor status (p < 0.001), post-treatment nodal status (p < 0.001), vascular invasion (p = 0.028), and tumor regression grade (p < 0.001). After uni- and multi-variable analysis of five-year survival, MLPH expression was still associated with lower DSS (hazard ratio (HR), 10.110; 95% confidence interval (CI), 2.178–46.920; p = 0.003) and MeFS (HR, 5.621; 95% CI, 1.762–17.931; p = 0.004). In conclusion, identifying MLPH expression could help to predict the response to chemoradiation and survival, and aid in personal therapeutic modification.

High-Risk Clinicopathological and Genetic Features and Outcomes in Patients Receiving Neoadjuvant Radiochemotherapy for Locally Advanced Rectal Cancer

Administering preoperative radiochemotherapy (RCT) in stage II-III tumors to locally advanced rectal carcinoma patients has proved to be effective in a high percentage of cases. Despite this, 20-30% of patients show no response or even disease progression. At present, preoperative response is assessed by a combination of imaging and tumor regression on histopathology, but recent studies suggest that various genetic abnormalities may be associated with the sensitivity or resistance of rectal cancer tumor cells to neoadjuvant therapy. In the present study we investigated the relationship between genetic lesions detected by high-density single-nucleotide polymorphisms (SNP) arrays 6.0 and response to neoadjuvant RCT, evaluated according to Dworak criteria in 39 rectal cancer tumors before treatment. The highest frequency of copy-number (CN) losses detected corresponded to chromosomes 18q (n = 27; 69%), 1p (n = 22; 56%), 15q (n = 19; 49%), 8p (n = 18; 48%), 4q (n = 17; 46%), and 22q (n = 17; 46%); in turn, CN gains more frequently involved chromosomes 20p (n = 22; 56%), 8p (n = 20; 51%), and 15q (n = 16; 41%). There was a significant association between alterations in the 1p, 3q, 7q, 12p, 17q, 20p, and 22q chromosomal regions and the degree of response to therapy prior to surgery. However, 4q, 15q11.1, and 15q14 chromosomal region alterations were identified as important by five prediction algorithms, i.e., those with the greatest influence on predicting the tumor response to treatment with preoperative RCT. Multivariate analysis of prognostic factors showed that gains on 15q11.1 and carcinoembryonic antigen (CEA) levels serum at diagnosis were the only independent variables predicting disease-free survival (DFS). Lymph node involvement also showed a prognostic impact on overall survival (OS) in the multivariate analysis. A deep-learning-based algorithm showed a 100% success rate in predicting both DFS and OS at 60 months after diagnosis of the disease. In summary, our results indicate the existence of an association between tumor genetic abnormalities at diagnosis, response to neoadjuvant therapy, and survival of patients with locally advanced rectal cancer. In addition to the clinical and biological characteristics of locally advanced rectal cancer patients, these could be used in the future as therapeutic and prognostic biomarkers, to identify patients sensitive or resistant to preoperative treatment, helping guide therapeutic decision-making. Additional prospective studies in larger series of patients are required to confirm the clinical utility of the newly identified biomarkers.

Unexpected tumor response to palliative pelvic radiotherapy in mismatch repair-deficient advanced prostate cancer: a case report

BACKGROUND

Mismatch-repair-deficiency resulting in microsatellite instability (MSI) may confer increased radiosensitivity in locally advanced/metastatic tumors and thus radiotherapy (RT) potentially might have a changing role in treating this subset of patients, alone or in combination with checkpoint inhibitors.

CASE PRESENTATION

We report a 76 year-old Italian male patient presenting with locally advanced undifferentiated prostate cancer (LAPC), infiltrating bladder and rectum. Molecular analysis revealed high-MSI with an altered expression of MSH2 and MSH6 at immunohistochemistry. Two months after 6 chemotherapy cycles with Docetaxel associated to an LHRH analogue, a computed tomography scan showed stable disease. After palliative RT (30 Gy/10 fractions) directed to the tumor mass with a 3D-conformal setup, a follow-up computed tomography scan at 8 weeks revealed an impressive response that remained stable at computed tomography after 9 months, with sustained biochemical response. To our knowledge, this is the first case of such a sustained response to low dose RT alone in high-MSI LAPC.

CONCLUSIONS

Routine evaluation of MSI in patients with locally problematic advanced tumors might change treatment strategy and treatment aim in this setting, from a purely palliative approach to a quasi-curative paradigm.

Comprehensive Analysis of DNA Methylation and Prediction of Response to NeoadjuvantTherapy in Locally Advanced Rectal Cancer

The treatment for locally advanced rectal carcinomas (LARC) is based on neoadjuvant chemoradiotherapy (nCRT) and surgery, which results in pathological complete response (pCR) in up to 30% of patients. Since epigenetic changes may influence response to therapy, we aimed to identify DNA methylation markers predictive of pCR in LARC patients treated with nCRT. We used high-throughput DNA methylation analysis of 32 treatment-naïve LARC biopsies and five normal rectal tissues to explore the predictive value of differentially methylated (DM) CpGs. External validation was carried out with The Cancer Genome Atlas-Rectal Adenocarcinoma (TCGA-READ 99 cases). A classifier based on three-CpGs DM (linked to OBSL1, GPR1, and INSIG1 genes) was able to discriminate pCR from incomplete responders with high sensitivity and specificity. The methylation levels of the selected CpGs confirmed the predictive value of our classifier in 77 LARCs evaluated by bisulfite pyrosequencing. Evaluation of external datasets (TCGA-READ, GSE81006, GSE75546, and GSE39958) reproduced our results. As the three CpGs were mapped near to regulatory elements, we performed an integrative analysis in regions associated with predicted cis-regulatory elements. A positive and inverse correlation between DNA methylation and gene expression was found in two CpGs. We propose a novel predictive tool based on three CpGs potentially useful for pretreatment screening of LARC patients and guide the selection of treatment modality.

Microsatellite Instability (MSI) as an Independent Predictor of Pathologic Complete Response (PCR) in Locally Advanced Rectal Cancer: A National Cancer Database (NCDB) Analysis

OBJECTIVE

The relationship between microsatellite instability (MSI) and response to neoadjuvant chemoradiation in rectal cancer is not well understood.

BACKGROUND

We utilized the National Cancer Database (NCDB) to investigate the association between MSI and pathologic complete response (pCR) in this patient population.

METHODS

We analyzed 5086 patients between 2010 and 2015 with locally advanced rectal cancer who were tested for MSI and treated definitively with chemoradiation followed by surgery. Primary comparison groups were between 4450 MSI-negative(-) and 636 MSI-positive(+) patients. Multivariable regression analysis was conducted to identify demographic, therapeutic, and clinical characteristics predictive of pCR. Cox proportional-hazard ratios were used for survival.

RESULTS

All patients were treated with definitive chemoradiation (median dose 50.4 Gy) followed by resection within 4 months. MSI(+) patients were associated with earlier year of diagnosis and higher-grade tumors (P < 0.05).The overall pCR rate was 8.6%, including 8.9% for MSI(-) and 5.9% for MSI(+) tumors (P = 0.01). Along with lower T stage, MSI(+) cases were significantly associated with a reduced pCR rate (odds ratio 0.65, 95% confidence interval 0.43-0.96) with multivariable analysis. The 5-year survival for patients with pCR was 93% compared with 73% without it (<0.001).

CONCLUSION

Microsatellite instability was independently associated with a reduction in pCR for locally advanced rectal cancer after neoadjuvant chemoradiation in this NCDB-based analysis.

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.

The potential predictive value of DEK expression for neoadjuvant chemoradiotherapy response in locally advanced rectal cancer

BACKGROUND

Limited data are available regarding the ability of biomarkers to predict complete pathological response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer. Complete response translates to better patient survival. DEK is a transcription factor involved not only in development and progression of different types of cancer, but is also associated with treatment response. This study aims to analyze the role of DEK in complete pathological response following chemoradiotherapy for locally advanced rectal cancer.

METHODS

Pre-treated tumour samples from 74 locally advanced rectal-cancer patients who received chemoradiation therapy prior to total mesorectal excision were recruited for construction of a tissue microarray. DEK immunoreactivity from all samples was quantified by immunohistochemistry. Then, association between positive stained tumour cells and pathologic response to neoadjuvant treatment was measured to determine optimal predictive power.

RESULTS

DEK expression was limited to tumour cells located in the rectum. Interestingly, high percentage of tumour cells with DEK positiveness was statistically associated with complete pathological response to neoadjuvant treatment based on radiotherapy and fluoropyrimidine-based chemotherapy and a marked trend toward significance between DEK positiveness and absence of treatment toxicity. Further analysis revealed an association between DEK and the pro-apoptotic factor P38 in the pre-treated rectal cancer biopsies.

CONCLUSIONS

These data suggest DEK as a potential biomarker of complete pathological response to treatment in locally advanced rectal cancer.

The clinical implications of immunogenomics in colorectal cancer: A path for precision medicine

Colorectal cancer (CRC) remains the third most common malignancy and the second-leading cause of cancer-related deaths in the United States. Large multi-omic databases, such as The Cancer Genome Atlas and the International Colorectal Cancer Subtyping Consortium, have identified distinct molecular subtypes related to anatomy. The identification of genomic alterations in CRC is now critical because of the recent success and US Food and Drug Administration approval of pembrolizumab and nivolumab for microsatellite-instable tumors. In parallel, landmark studies have established the prognostic significance of the CRC tumor-infiltrating lymphocyte and the clinical impact of the tumor immune microenvironment. As a result, there is a growing appreciation for immunogenomics, the interconnected relation between tumor genomics and the immune microenvironment. The clinical implications of CRC immunogenomics continue to expand, and it will likely serve as a guide for next-generation immunotherapy strategies for improving outcomes for this disease. Cancer 2018;124:1650-9. © 2018 American Cancer Society.

Population-based study of effectiveness of neoadjuvant radiotherapy on survival in US rectal cancer patients according to age

Recent cancer researches pay more attention to younger patients due to the variable treatment response among different age groups. Here we investigated the effectiveness of neoadjuvant radiation on the survival of younger and older patients in stage II/III rectal cancer. Data was obtained from Surveillance, Epidemiology, and End Results (SEER) database (n = 12801). Propensity score matching was used to balance baseline covariates according to the status of neoadjuvant radiation. Our results showed that neoadjuvant radiation had better survival benefit (Log-rank P = 3.25e-06) and improved cancer-specific 3-year (87.6%; 95% CI: 86.4-88.7% vs. 84.1%; 95% CI: 82.8-85.3%) and 5-year survival rates (78.1%; 95% CI: 76.2-80.1% vs. 77%; 95% CI: 75.3-78.8%). In older groups (>50), neoadjuvant radiation was associated with survival benefits in stage II (HR: 0.741; 95% CI: 0.599-0.916; P = 5.80e-3) and stage III (HR: 0.656; 95% CI 0.564-0.764; P = 5.26e-08). Interestingly, neoadjuvant radiation did not increase survival rate in younger patients (< = 50) both in stage II (HR: 2.014; 95% CI: 0.9032-4.490; P = 0.087) and stage III (HR: 1.168; 95% CI: 0.829-1.646; P = 0.372). Additionally, neoadjuvant radiation significantly decreased the cancer-specific mortality in older patients, but increased mortality in younger patients. Our results provided new insights on the neoadjuvant radiation in rectal cancer, especially for the younger patients.

Decreased PLK1 expression denotes therapy resistance and unfavourable disease-free survival in rectal cancer patients receiving neoadjuvant chemoradiotherapy

AIM

Polo-like kinase 1 (Plk1) plays a key role in mitotic cell division and DNA damage repair. It has been observed that either up-regulated or down-regulated Plk1 could induce mitotic defects that results in aneuploidy and tumorigenesis, probably depending on the context. Few previous reports have associated Plk1 expression with prognosis and response to radiotherapy in rectal carcinomas. The aim of this study is to investigate the prognostic impact of Plk1 expression and its role in predicting response to neoadjuvant cheomoradiotherapy in rectal cancer.

METHODS AND RESULTS

Immunohistochemical analysis of Plk1 expression was performed in the pre-treatment tumour specimens from 75 rectal cancer patients. We analysed the assocation between Plk1 expression and clinicopathological parameters, pathologic response and outcome. Opposed to previous reports on this issue, low expression of Plk1 was significantly associated with a high grade of differentiation (P=0.0007) and higher rate of distant metastasis (P=0.014). More importantly, decreased levels of Plk1 were associated with absence of response after neoadjuvant therapy (P=0.049). Moreover, low Plk1 expression emerged as an unfavourable prognostic factor for disease-free survival in the non-responder group of patients (P=0.037).

CONCLUSIONS

Decreased Plk1 expression was associated with poor pathologic response and worse disease-free survival in rectal cancer patients receiving neoadjuvant chemoradiotherapy, suggesting Plk1 as a clinically relevant marker to predict chemoradiotherapy response and outcome.

Magnetic Resonance Tumor Regression Grade and Residual Mucosal Abnormality as Predictors for Pathological Complete Response in Rectal Cancer Postneoadjuvant Chemoradiotherapy

BACKGROUND

Pathological complete response after chemoradiotherapy for rectal cancer occurs in 10% to 30% of patients. The best method to identify such patients remains unclear. Clinical assessment of residual mucosal abnormality is considered the most accurate method. In our institution, magnetic resonance tumor regression grade is performed as routine to assess response.

OBJECTIVE

The purpose of this study was to compare the sensitivity of magnetic tumor regression grade against residual mucosal abnormality in detecting patients with a pathological complete response.

DESIGN

Magnetic tumor regression grade scores from reported posttreatment MRI scans were documented. Magnetic tumor regression grade 1 to 3 was defined as likely to predict complete or near complete response. Gross appearances of the mucosa were derived from histopathology reports and used as a surrogate for clinical assessment (previously validated). Final histopathological staging was used to determine response.

SETTINGS

The study was conducted at Royal Marsden National Health Service Trust, United Kingdom.

PATIENTS

A total of 143 patients with rectal adenocarcinoma, diagnosed between September 1, 2009, and September 1, 2013, who received neoadjuvant chemoradiotherapy before curative surgery were included.

MAIN OUTCOME MEASURES

The sensitivity of magnetic tumor regression grade and residual mucosal abnormality in detecting patients with pathological complete response were measured

RESULTS

: Eighteen patients had a pathological complete response. Seventeen were detected using magnetic resonance tumor regression grade 1 to 3, with sensitivity 94% (95% CI, 0.74-0.99), and 10 were detected using residual mucosal abnormality, with sensitivity 62% (95% CI, 0.38-0.81). There was no statistical difference between the false positive rates for either method. Magnetic tumor regression grade identified 10 times more patients with a pathological complete response (diagnostic OR = 10.2 (95% CI, 1.30-73.73)) compared with clinical assessment with RMA.

LIMITATIONS

Residual mucosal abnormality was used as a surrogate marker for endoscopic appearances.

CONCLUSIONS

Most patients with rectal cancer who have a pathological complete response do not manifest a complete response at the mucosal level. Magnetic tumor regression grade is able to identify 10 times more patients than clinical assessment, with no significant compromise in the false positive rate.

Seven low-mass ions in pretreatment serum as potential predictive markers of the chemoradiotherapy response of rectal cancer

Preoperative chemoradiotherapy (CRT) is generally performed for locally advanced rectal cancer (LARC, cStage 2 or 3) to improve local disease control and patient survival. The pathological tumor response to CRT is a surrogate marker that is associated with oncological outcome. Thus, markers that predict the response to CRT would be valuable for individualizing treatment for LARC patients. The current study used metabolomics-based approaches to identify molecular markers that predict the response to CRT. Seventy-six patients with LARC who received pelvic radiotherapy and concurrent chemotherapy using tegafur-uracil and leucovorin were enrolled. Radical surgery was performed 6-8 weeks after the completion of CRT. The postsurgical pathological CRT response was evaluated using the ypStage or tumor regression grade. Profiling patterns of low-mass ions (LMIs) in the pretreatment sera were obtained from all patients using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Our previously developed two-step algorithms, which showed a powerful diagnostic capability during colorectal cancer screening, were then used to screen for meaningful LMIs with discriminatory power. One combination consisting of seven LMIs was identified, whose discriminatory score separated a good CRT response (ypStage 0-1) from a poor CRT response (ypStage 3-4) successfully. However, each individual LMI alone showed insignificant discriminatory power. This finding suggests that analysis of the LMIs in pretreatment serum could serve as a predictive marker of the CRT response in patients with LARC.

An integrative approach for the identification of prognostic and predictive biomarkers in rectal cancer

Introduction

Colorectal cancer is the third most common cancer in the world, a small fraction of which is represented by locally advanced rectal cancer (LARC). If not medically contraindicated, preoperative chemoradiotherapy, represent the standard of care for LARC patients. Unfortunately, patients shows a wide range of response rates in which approximately 20% has a complete pathological response, whereas in 20 to 40% the response is poor or absent.

Results

The following specific gene signature, able to discriminate responders' patients from non-responders, were founded: AKR1C3, CXCL11, CXCL10, IDO1, CXCL9, MMP12 and HLA-DRA. These genes are mainly involved in immune system pathways and interact with drugs traditionally used in the adjuvant treatment of rectal cancer.

Discussion

The present study suggests that new ideas for therapy could be found not only limited to studying genes differentially expressed between the two groups of patients but deepening the mechanisms, associated to response, in which they are involved.

Methods

Gene expression studies performed by: Agostini et al., Rimkus et al. and Kim et al. have been merged through a meta-analysis of the raw data. Gene expression data-sets have been processed using A-MADMAN. Common differentially expressed gene (DEG) were identified through SAM analysis. To further characterize the identified DEG we deeply investigated its biological role using an integrative computational biology approach.

Pathologic Complete Response in Rectal Cancer: Can We Detect It? Lessons Learned From a Proposed Randomized Trial of Watch-and-Wait Treatment of Rectal Cancer

BACKGROUND

Chemoradiotherapy has the potential to downsize and downstage tumors before surgery, decrease locoregional recurrence, and induce a complete sterilization of tumor cells for middle and low locally advanced rectal cancer. A watch-and-wait tactic has been proposed for patients with clinical complete response.

OBJECTIVE

The purpose of this study was to verify our ability to identify complete clinical response in patients with rectal cancer based on clinical and radiologic criteria.

DESIGN

This was a prospective study.

SETTINGS

The study was conducted at a single institution, in the setting of a watch-and-wait randomized trial.

PATIENTS

Consecutive patients with stage T3 to T4N0M0 or T(any)N+M0 cancer located within 10 cm from anal verge or T2N0 within 7 cm from anal verge were included in the study. Patients were staged and restaged 8 weeks after completion of chemoradiation (5-fluorouracil, 5040 cGy) by digital examination, colonoscopy, pelvic MRI, and thorax and abdominal CT scans.

MAIN OUTCOME MEASURES

Clinical and radiologic judgments of tumor response were compared with pathologic response of patients treated by total mesorectal excision or clinical follow-up of patients selected for nonoperative treatment.

RESULTS

A total of 118 patients were treated. Six patients were considered clinic complete responders (2 randomly assigned for surgery (1 ypT0N0 and 1 ypT2N0) and 4 patients randomly assigned for observation (3 sustained clinic complete response and 1 had tumor regrowth)). The 112 clinic incomplete responders underwent total mesorectal excision, and 18 revealed pathologic complete response. These 18 patients were not considered complete responders at restaging because they presented at least 1 of the following conditions: mucosal ulceration and/or deformity and/or substenosis of rectal lumen at digital rectal examination and colonoscopy (n = 16), ymrT1 to T4 (n = 16), ymrN+ (n = 2), involvement of circumferential resection margin on MRI (n = 3), extramural vascular invasion on MRI (n = 4), MRI tumor response grade 2 to 4 (n = 15), and pelvic side wall lymph node involvement on MRI (n = 1). Sensitivity for identification of ypT0N0 or sustained clinic complete response was 18.2%.

LIMITATIONS

This study has a short follow-up and small sample size. Radiologists who reviewed the restaging examination were not blinded to the pretreatment stage. Only 1 radiologist read the images of each patient.

CONCLUSIONS

Evaluation of clinic complete response according to current adopted criteria has low sensitivity because pathologic complete response more frequently presented as clinic incomplete response (see Video, Supplemental Digital Content 1, http://links.lww.com/DCR/A221).

Predicting pathological complete response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer: a systematic review

AIM

Approximately 20% of patients treated with neoadjuvant chemoradiotherapy (nCRT) for locally advanced rectal cancer achieve a pathological complete response (pCR) while the remainder derive the benefit of improved local control and downstaging and a small proportion show a minimal response. The ability to predict which patients will benefit would allow for improved patient stratification directing therapy to those who are likely to achieve a good response, thereby avoiding ineffective treatment in those unlikely to benefit.

METHOD

A systematic review of the English language literature was conducted to identify pathological factors, imaging modalities and molecular factors that predict pCR following chemoradiotherapy. PubMed, MEDLINE and Cochrane Database searches were conducted with the following keywords and MeSH search terms: 'rectal neoplasm', 'response', 'neoadjuvant', 'preoperative chemoradiation', 'tumor response'. After review of title and abstracts, 85 articles addressing the prediction of pCR were selected.

RESULTS

Clear methods to predict pCR before chemoradiotherapy have not been defined. Clinical and radiological features of the primary cancer have limited ability to predict response. Molecular profiling holds the greatest potential to predict pCR but adoption of this technology will require greater concordance between cohorts for the biomarkers currently under investigation.

CONCLUSION

At present no robust markers of the prediction of pCR have been identified and the topic remains an area for future research. This review critically evaluates existing literature providing an overview of the methods currently available to predict pCR to nCRT for locally advanced rectal cancer. The review also provides a comprehensive comparison of the accuracy of each modality.

Immunological Landscape and Clinical Management of Rectal Cancer

The clinical management of rectal cancer and colon cancer differs due to increased local relapses in rectal cancer. However, the current molecular classification does not differentiate rectal cancer and colon cancer as two different entities. In recent years, the impact of the specific immune microenvironment in cancer has attracted renewed interest and is currently recognized as one of the major determinants of clinical progression in a wide range of tumors. In colorectal cancer, the density of lymphocytic infiltration is associated with better overall survival. Due to the need for biomarkers of response to conventional treatment with chemoradiotherapy in rectal tumors, the immune status of rectal cancer emerges as a useful tool to improve the management of patients.

Locally advanced rectal cancers with simultaneous occurrence of KRAS mutation and high VEGF expression show invasive characteristics

In this study, we investigated the mutation status of KRAS gene in pretherapeutic and preoperative biopsies in 63 specimens of locally advanced rectal cancers in order to evaluate its potential predictive and/or prognostic role. Regions of interest of KRAS exon 2 were amplified and visualized on 2% agarose gel. Obtained PCR products were subjected to direct sequencing. KRAS mutations were detected in 35% of patients, 91% of which were located in codon 12 and 9% in codon 13. In general, KRAS mutation status did not affect the response to neoadjuvant chemoradiotherapy (CRT). However, patients harboring mutated KRAS gene, simultaneously with high vascular endothelial growth factor (VEGF) expression, exhibited a worse response to CRT (p=0.030), a more frequent appearance of local recurrences and distant metastasis (p=0.003), and shorter overall survival (p=0.001) compared to all others. On the contrary, patients with GGT>GCT KRAS mutation exhibited a significantly better response to CRT than those with any other type of KRAS mutation (p=0.017). Moreover, the presence of GGT>GCT mutation was associated with low VEGF and Ki67 expression (p=0.012 in both cases), parameters related to less aggressiveness of the disease. Our results suggest that KRAS mutation status could have some predictive and prognostic importance in rectal cancer when analyzed together with other parameters, such as VEGF and Ki67 expression. In addition, it seems that not only the presence but the type of KRAS mutation is important for examining its impact on CRT response.

Distal intramural and tumor spread in the mesorectum after neoadjuvant radiochemotherapy in rectal cancer: about 124 consecutive patients

This observational prospective study aimed to assess the distribution of intramural and mesorectal tumor spread in mid/low rectal cancer after neoadjuvant radiochemotherapy. Distribution of mesorectal metastatic lymph nodes (MLNs) and mesorectal extranodal cancer tissue (EX), according to the tumor location, were analyzed. Distal intramural tumor spread was also performed. A total of 1676 LNs, 135 MLNs, and 69 EX were detected on 124 consecutive surgical specimens. Forty-two patients (34%) had MLNs. Six patients (4.8%) were classified as ypN1c. Distal viable cancer spread was observed in 3 patients (2.4%), all with mid rectal carcinoma. Two patients (1.6%) presented distal direct intramural extension less than 1 cm; and 1 (0.8%), with EX localized no more than 2 cm from the lower edge of the tumor. MLNs (76%) and EX (94%) were preferentially localized in the peritumoral area and in the first 3 cm just above the tumor. No viable distal intramural or mesorectal spread was observed in low rectal carcinoma. Distal intramural and mesorectal cancer spread is a rare event after neoadjuvant RCT. These results suggest that the 1-cm distal margin recommended in patients with low rectal carcinoma could be reduced with insurance to obtain a negative distal margin. The knowledge of preferential localization of MLNs and EX would help the pathologist to improve patient's lymph node staging.

NPTX2 is associated with neoadjuvant therapy response in rectal cancer

BACKGROUND

Neoadjuvant chemoradiation (CRT) is recommended for locally advanced rectal cancer. Tumor response varies from pathologic complete response (pCR) to no tumor regression. The mechanisms behind CRT resistance remain undefined. In our previously generated complementary DNA microarrays of pretreatment biopsies from rectal cancer patients, neuronal pentraxin 2 (NPTX2) expression discriminated patients with pCR from those with residual tumor. As tumor response is prognostic for survival, we sought to evaluate the clinical relevance of NPTX2 in rectal cancer.

MATERIALS AND METHODS

Real-time quantitative polymerase chain reaction was used to evaluate NPTX2 messenger RNA expression in individual rectal cancers before CRT. Tumors with NPTX2 expression <50% of normal rectum were defined as NPTX2-low and those with >50% were defined as NPTX2-high. NPTX2 levels were compared to response to therapy and oncologic outcomes using Mann-Whitney, Kruskal-Wallis, chi-square, and Mantel-Cox (log-rank) tests, as appropriate.

RESULTS

Rectal cancers from 40 patients were included. The mean patient age was 56.8 years, and 30% were female. pCR was achieved in eight of 40 patients (20%). In these patients, messenger RNA NPTX2 levels were significantly decreased compared to those with residual cancer (fold change 30.4, P = 0.017). Patients with NPTX2-low tumors (n = 13) achieved improved response to treatment (P = 0.012 versus NPXT2-high tumors), with 38.5% and 46.1% of patients achieving complete or moderate response, respectively. Of patients with NPTX2-high tumors (n = 27), 11.1% and 18.5% achieved complete or moderate response, respectively. No recurrence or death was recorded in patients with NPTX2-low tumors, reflecting more favorable disease-free survival (P = 0.045).

CONCLUSIONS

Decreased NPTX2 expression in rectal adenocarcinomas is associated with improved response to CRT and improved prognosis. Further studies to validate these results and elucidate the biological role of NPTX2 in rectal cancer are needed.

MicroRNA-21 predicts response to preoperative chemoradiotherapy in locally advanced rectal cancer

PURPOSE

The treatment of choice for locally advanced rectal cancer is preoperative chemoradiotherapy. Despite half of patients do not respond and suffer unnecessary toxicities and surgery delays, there are no biomarkers to guide preoperative CRT outcome. MicroRNA-21 has been related to acquisition of 5-fluorouracil resistance; however, its potential predictive value of response to preoperative chemoradiotherapy in locally advanced rectal cancer remains unknown.

METHODS

Nighty-two patients diagnosed with locally advanced rectal cancer who were preoperatively treated with chemoradiotherapy were selected for this study. Moreover, microRNA-21 expression was quantified in formalin-fixed paraffin-embedded biopsies from this cohort, and the results obtained were correlated with clinical and molecular characteristics, pathological response, and outcome.

RESULTS

MicroRNA-21 was found overexpressed in 77.6% cases, and significantly correlated with tumor grade after preoperative chemoradiotherapy (P = 0.013) and with pathological response (P = 0.013). The odds ratio of having miR-21 overexpression and not getting a respond to chemoradiotherapy resulted in 9.75 CI 2.24 to 42. Sensitivity, specificity, negative predictive values, and positive predictive value were 86.6, 60, 42.8, and 92%, respectively. Multivariate analysis confirmed the clinical significance of miR-21 determining preoperative chemoradiotherapy response.

CONCLUSIONS

MicroRNA-21 expression efficiently predicts preoperative chemoradiotherapy pathological response in locally advanced rectal cancer.

A functional biological network centered on XRCC3: a new possible marker of chemoradiotherapy resistance in rectal cancer patients

Preoperative chemoradiotherapy is widely used to improve local control of disease, sphincter preservation and to improve survival in patients with locally advanced rectal cancer. Patients enrolled in the present study underwent preoperative chemoradiotherapy, followed by surgical excision. Response to chemoradiotherapy was evaluated according to Mandard's Tumor Regression Grade (TRG). TRG 3, 4 and 5 were considered as partial or no response while TRG 1 and 2 as complete response. From pretherapeutic biopsies of 84 locally advanced rectal carcinomas available for the analysis, only 42 of them showed 70% cancer cellularity at least. By determining gene expression profiles, responders and non-responders showed significantly different expression levels for 19 genes (P < 0.001). We fitted a logistic model selected with a stepwise procedure optimizing the Akaike Information Criterion (AIC) and then validated by means of leave one out cross validation (LOOCV, accuracy = 95%). Four genes were retained in the achieved model: ZNF160, XRCC3, HFM1 and ASXL2. Real time PCR confirmed that XRCC3 is overexpressed in responders group and HFM1 and ASXL2 showed a positive trend. In vitro test on colon cancer resistant/susceptible to chemoradioterapy cells, finally prove that XRCC3 deregulation is extensively involved in the chemoresistance mechanisms. Protein-protein interactions (PPI) analysis involving the predictive classifier revealed a network of 45 interacting nodes (proteins) with TRAF6 gene playing a keystone role in the network. The present study confirmed the possibility that gene expression profiling combined with integrative computational biology is useful to predict complete responses to preoperative chemoradiotherapy in patients with advanced rectal cancer.

Predictive and prognostic biomarkers for neoadjuvant chemoradiotherapy in locally advanced rectal cancer

Locally advanced rectal cancer is regularly treated with trimodality therapy consisting of neoadjuvant chemoradiation, surgery and adjuvant chemotherapy. There is a need for biomarkers to assess treatment response, and aid in stratification of patient risk to adapt and personalise components of the therapy. Currently, pathological stage and tumour regression grade are used to assess response. Experimental markers include proteins involved in cell proliferation, apoptosis, angiogenesis, the epithelial to mesenchymal transition and microsatellite instability. As yet, no single marker is sufficiently robust to have clinical utility. Microarrays that screen a tumour for multiple promising candidate markers, gene expression and microRNA profiling will likely have higher yield and it is expected that a combination or panel of markers would prove most useful. Moving forward, utilising serial samples of circulating tumour cells or circulating nucleic acids can potentially allow us to demonstrate tumour heterogeneity, document mutational changes and subsequently measure treatment response.

YKL-40/c-Met expression in rectal cancer biopsies predicts tumor regression following neoadjuvant chemoradiotherapy: a multi-institutional study

BACKGROUND

Neoadjuvant chemo-radiotherapy (CRT) followed by surgical resection is the standard treatment for locally advanced rectal cancer, although complete tumor pathological regression is achieved in only up to 30% of cases. A clinicopathological and molecular predictive stratification of patients with advanced rectal cancer is still lacking. Here, c-Met and YKL-40 have been studied as putative predictors of CRT response in rectal cancer, due to their reported involvement in chemoradioresistance in various solid tumors.

MATERIAL AND METHODS

A multicentric study was designed to assess the role of c-Met and YKL-40 expression in predicting chemoradioresistance and to correlate clinical and pathological features with CRT response. Immunohistochemistry and fluorescent in situ hybridization for c-Met were performed on 81 rectal cancer biopsies from patients with locally advanced rectal adenocarcinoma. All patients underwent standard (50.4 gy in 28 fractions + concurrent capecitabine 825 mg/m2) neoadjuvant CRT or the XELOXART protocol. CRT response was documented on surgical resection specimens and recorded as tumor regression grade (TRG) according to the Mandard criteria.

RESULTS

A significant correlation between c-Met and YKL-40 expression was observed (R = 0.43). The expressions of c-Met and YKL-40 were both significantly associated with a lack of complete response (86% and 87% of c-Met and YKL-40 positive cases, p< 0.01 and p = 0.006, respectively). Thirty of the 32 biopsies co-expressing both markers had partial or absent tumor response (TRG 2-5), strengthening their positive predictive value (94%). The exclusive predictive role of YKL-40 and c-Met was confirmed using a multivariate analysis (p = 0.004 and p = 0.007 for YKL-40 and c-Met, respectively). TRG was the sole morphological parameter associated with poor outcome.

CONCLUSION

c-Met and YKL-40 expression is a reliable predictor of partial/absent response to neoadjuvant CRT in rectal cancer. Targeted therapy protocols could take advantage of prior evaluations of c-MET and YKL-40 expression levels to increase therapeutic efficacy.

[Preoperative chemoradiotherapy for rectal cancer: experience from one centre]

PURPOSE

In recent decades, the management of rectal cancer has been significantly improved by optimizing the surgical treatment with the total mesorectal excision and the development of neoadjuvant radiotherapy with or without chemotherapy. In this study, we investigated the impact of changes in practice over a period of 15 years in an expert centre.

PATIENTS AND METHODS

A monocentric study was conducted retrospectively on cT3-resectable T4 patients who received chemoradiotherapy for a locally advanced rectal adenocarcinoma between 1993 and 2008. We studied sphincter preservation, pathological complete response (ypT0), survival, and toxicities by different concomitant chemotherapy and treatment period.

RESULTS

Among the 179 patients who had a chemoradiotherapy, 56.4% were received concomitant 5-fluoro-uracil-leucovorin, 28.5% with concomitant capecitabine, and 15.1% with concomitant oxaliplatin and capecitabine. The average dose of radiotherapy was 45 Gy (25×1.8 Gy). Five-year disease-free survival was 74.3% and overall survival 68.8%. The rate of local recurrence and distant metastases were 6.1 and 23.6%. In multivariate analysis, concomitant chemotherapy oxaliplatin and capecitabine improved the pathological complete response rate (ypT0; capecitabine: 6%, 5-fluoro-uracil-leucovorin: 10.3%, capecitabine-oxaliplatin: 22.2%), but not significantly (P=0.12) and with more toxicities, and treatment interruptions. Sphincter preservation rate was not improved significantly during the study period (1993-2004 vs. 2005-2008), but disease-free survival improved from 72.2% up to 87.5% (P=0.03).

CONCLUSION

Our results are consistent with those published in the literature. Concomitant chemotherapy with 5-fluoro-uracil or capecitabine remains the standard scheme. Upfront chemotherapy, before chemoradiotherapy, should be investigated with regard to the predominance of metastasis.

Insulin-like growth factor receptor-1 overexpression is associated with poor response of rectal cancers to radiotherapy

AIM: To explore the potential correlation between insulin-like growth factor receptor-1 (IGF-1R) expression and rectal cancer radiosensitivity.

METHODS: Eighty-seven rectal cancer patients (cTNM I-III) treated in our department between January 2011 and December 2012 were enrolled. All subjects were treated with preoperative radiotherapy and radical resection of rectal carcinoma. Immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR) were performed to detect IGF-1R expression in pre-treatment and postoperative colorectal cancer specimens. Radiosensitivity for rectal cancer specimens was evaluated by observing rectal carcinoma mass regression combined with fibrosis on HE staining, degree of necrosis and quantity of remaining tumor cells. The relative IGF-1R expression was evaluated for association with tumor radiosensitivity.

RESULTS: Immunohistochemistry showed diffuse IGF-1R staining on rectal cancer cells with various degrees of signal density. IGF-1R expression was significantly correlated with cTNM staging (P = 0.012) while no significant association was observed with age, sex, tumor size and degree of differentiation (P = 0.424, 0.969, 0.604, 0.642). According to the Rectal Cancer Regression Grades (RCRG), there were 31 cases of RCRG1 (radiation sensitive), 28 cases of RCRG2 and 28 cases of RCRG3 (radiation resistance) in 87 rectal cancer subjects. IGF-1R protein hyper-expression was significantly correlated with a poor response to radiotherapy (P < 0.001, r = 0.401). RT-PCR results from pre-radiation biopsy specimens also showed that IGF-1R mRNA negative group exhibited a higher radiation sensitivity (P < 0.001, r = 0.497). Compared with the pre-radiation biopsy specimens, the paired post-operative specimens showed a significantly increased IGF-1R protein and mRNA expression in the residual cancer cells (P < 0.001, respectively).

CONCLUSION: IGF-1R expression level may serve as a predictive biomarker for radiosensitivity of rectal cancer before preoperative radiotherapy.

Predictive markers of response to neoadjuvant therapy in rectal cancer

BACKGROUND

Neoadjuvant therapy followed by radical surgery is the standard treatment in locally advanced rectal cancer. It is important to predict the response because the treatment has side effects and is costly. The aim of this study was to establish the relationship among clinical, pathologic, and molecular biomarkers and the response to neoadjuvant therapy.

METHOD

A total of 130 patients with locally advanced mid and low rectal cancer who underwent long-course radiotherapy with 5-FU based chemotherapy followed by radical surgical resection were included in the study. Clinical and pathologic data were collected. Paraffin-embedded sections obtained in diagnostic biopsies were assessed by immunohistochemical staining for molecular markers and classified using a semiquantitative method. Results were related with T-downstaging and tumor regression grade using Mandard scoring system on surgical specimens.

RESULTS

Pathologic complete response was found in 19 patients (14.6%), while in another 18 (13.8%) only minor residual disease was seen in the rectal wall. T-downstaging was observed in 63 (48.5%). The average of lymph node retrieval in the surgical specimens was 9.4. Regarding predictive markers of response, there was significant correlation between the expression of B-cell lymphoma 2 (P = 0.005), β-catenin (P = 0.03), vascular endothelial growth factor (P = 0.048) and apoptotic protease activating factor 1 (P = 0.03), tumor differentiation grade (P < 0.001), and response in the univariate analysis. T-downstaging was associated with vascular endothelial growth factor expression (P = 0.03) and tumor differentiation grade (P < 0.001). Significant parameters found in the multivariate analysis were tumor differentiation grade and Bcl-2 expression.

CONCLUSIONS

Pathologic and molecular biomarkers in the diagnostic biopsies may help us predict tumor response to chemoradiation in rectal cancer patients.

Impact of perineural and lymphovascular invasion on oncological outcomes in rectal cancer treated with neoadjuvant chemoradiotherapy and surgery

BACKGROUND

The prognostic significance of perineural and/or lymphovascular invasion (PLVI) and its relationship with tumor regression grade (TRG) in patients with locally advanced rectal cancer (LARC) treated with neoadjuvant chemoradiotherapy (CRT) and surgery.

METHODS

A total of 324 patients with LARC were treated with CRT and operated on between January 1992 and June 2007. Tumors were graded using a quantitative 5-grade TRG classification and the presence of PLVI was histologically studied.

RESULTS

At a median follow-up of 79.0 months (range 3-250 months), a total of 80 patients (24.7%) relapsed. The observed 5- and 10-year overall survival (OS) was 83.2 and 74.9 %, respectively. The 5- and 10-year disease-free survival (DFS) was 75.1 and 71.4%, respectively. A significant correlation was found between the TRG and survival (log rank, p < 0.001). The 10-year OS was 32.7% for grade 1, 63.8% for grade 2, 75.0% for grade 3, 90.4% for grade 3+, and 96.0%,for grade 4. The 10-year DFS was 31.8% for grade 1, 58.6% for grade 2, 70.4% for grade 3, 88.4% for grade 3+, and 97.1% for grade 4. In patients with PLVI, the TRG had no impact on survival. When excluding patients with PLVI, the TRG was an independent prognostic factor for OS and DFS.

CONCLUSIONS

The presence of PLVI is a more powerful prognostic factor than TRG in LARC patients treated with neoadjuvant CRT followed by surgery. PLVI denotes an aggressive phenotype, suggesting that these patients may benefit from adjuvant systemic therapy.

Global DNA methylation is altered by neoadjuvant chemoradiotherapy in rectal cancer and may predict response to treatment - A pilot study

AIM

In rectal cancer, not all tumours display a response to neoadjuvant treatment. An accurate predictor of response does not exist to guide patient-specific treatment. DNA methylation is a distinctive molecular pathway in colorectal carcinogenesis. Whether DNA methylation is altered by neoadjuvant treatment and a potential response predictor is unknown. We aimed to determine whether DNA methylation is altered by neoadjuvant chemoradiotherapy (CRT) and to determine its role in predicting response to treatment.

PATIENTS AND METHODS

Fifty-three (n = 53) patients with locally advanced rectal cancers treated with neoadjuvant CRT followed by surgery were identified from the pathology databases of 2 tertiary referral centres over a 4-year period. Immunohistochemical staining of treatment specimens was carried out using the 5-Methylcytidine (Eurogentec, Seraing, Belgium) antibody. Quantitative analysis of staining was performed using an automated image analysis platform. The modified tumour regression grading system was used to assess tumour response to neoadjuvant therapy.

RESULTS

Seven (13%) patients showed complete pathological response while 46 (87%) patients were partial responders to neoadjuvant treatment. In 38 (72%) patients, significant reduction in methylation was observed in post-treatment resection specimens compared to pre-treatment specimens (171.5 vs 152.7, p = 0.01); in 15 (28%) patients, methylation was increased. Pre-treatment methylation correlated significantly with tumour regression (p < 0.001), T-stage (p = 0.005), and was able to predict complete and partial pathological responders (p = 0.01).

CONCLUSION

Neoadjuvant CRT appears to alter the rectal cancer epigenome. The significant correlation between pre-treatment DNA methylation with tumour response suggests a potential role for methylation as a biomarker of response.

Clinical criteria underestimate complete pathological response in rectal cancer treated with neoadjuvant chemoradiotherapy

BACKGROUND

Published criteria define specific mucosal features of clinical complete response for rectal cancer after neoadjuvant chemoradiotherapy.

OBJECTIVE

The aim of this study was to determine the performance of these criteria to identify a pathological complete response.

DESIGN

Histopathology reports were retrieved for consecutive rectal cancers treated with neoadjuvant therapy followed by proctectomy. The mucosal appearance of residual disease was compared with the final pathological stage.

SETTING

This study was conducted at a single-institution, tertiary referral center.

PATIENTS

The study included 238 patients.

INTERVENTIONS

All patients underwent neoadjuvant chemoradiation followed by proctectomy between 1997 and 2007.

MAIN OUTCOME MEASURES

Gross mucosal appearance was compared with the final pathological stage.

RESULTS

Following neoadjuvant chemoradiation, 61 of 238 (25%) patients were downstaged to ypT0. Forty-five of these 61 patients (74%) had a residual mucosal abnormality that precluded assignment of a complete response. Of these, 40 had residual ulcers (up to 10 mm in depth) and 5 had exophytic lesions. The remaining 16 patients with pathological complete response fulfilled criteria for clinical complete response and had either no visible abnormality or a scar. Although mucosal complete clinical response was statistically associated with ypT0 status (p < 0.0001), 6 of 22 (27%) patients with mucosal complete clinical response still had residual disease. Smaller size of residual mucosal abnormality was also associated with ypT0 status (p = 0.002).

LIMITATIONS

This is a retrospective study and preoperative clinical assessment of response is not recorded for comparison to resected specimens.

CONCLUSIONS

The majority of patients attaining ypT0 status do not display mucosal features of complete response. When present, a mucosal complete response is statistically associated with ypT0 status, but is poorly sensitive. If rectal conservation after chemoradiation is to be pursued, alternative means of restaging are required to maximize the number who might benefit from this approach.

CMTM3 inhibits human testicular cancer cell growth through inducing cell-cycle arrest and apoptosis

Human CMTM3 has been proposed as a putative tumor suppressor gene. The loss of CMTM3 has been found in several carcinomas. However, the regulation of CMTM3 expression and its function in tumor progression remain largely unknown. Here, we investigated the regulation of CMTM3 expression, function and molecular mechanism in human testicular cancer cells. CMTM3 was frequently downregulated or silenced in testicular cancer cell lines and tumor tissues but highly expressed in normal testis tissues. The re-expression of CMTM3 significantly suppressed the colony formation, proliferation, and migration capacity of testicular cancer cells by inducing a G2 cell cycle arrest and apoptosis. Moreover, the re-expression of CMTM3 activated the transcription of p53, induced p53 accumulation, up-regulated the expression of p21, and increased the cleavage of caspase 9, 8, 3, and PARP. The downregulation of CMTM3 in clinical tumor tissues was associated with the methylation of a single CpG site located within the Sp1/Sp3-responsive region of the core promoter. These results indicate that CMTM3 can function as tumor suppressor through the induction of a G2 cell cycle arrest and apoptosis. CMTM3 is thus involved in testicular cancer pathogenesis, and it is frequently at least partially silenced by the methylation of a single, specific CpG site in tumor tissues.

Lack of M30 expression correlates with factors reflecting tumor progression in rectal cancer with preoperative chemoradiotherapy

Preoperative chemoradiotherapy (CRT) is an effective tool for local control that functions by inducing cancer cell apoptosis and inhibiting cell growth. The aim of this study was to evaluate the expression of caspase-cleaved keratin 18 cytoskeletal protein, M30, which is known as an apoptotic marker in residual rectal cancer following preoperative CRT. A total of 72 patients with rectal cancer who had undergone preoperative CRT were enrolled in this study. Immunostaining with M30 cytodeath antibody was performed and the correlation between M30 staining and clinicopathological variables was analyzed. Furthermore, we examined the correlation of M30 staining with the expression of Bax, Bcl-2, Ki67 and PCNA using transcriptional and immunohistochemical analyses. The results showed that 34 (47%) patients were positive for M30 staining. Lack of M30 expression was significantly correlated with advanced T stage, postoperative stage and tumor recurrence (P<0.05). Patients with M30 staining had better recurrence-free survival (RFS) than those without it (P=0.0301). In the immunohistochemical analysis, residual cancer cells with M30 staining lacked Ki67 expression. No significant correlation was observed between M30 positivity and the gene expression of apoptotic and proliferative markers. In conclusion, findings of the present study suggested that the evaluation of M30 expression may be useful in the prediction of tumor recurrence in rectal cancer patients who have been treated with preoperative CRT.

Local excision after neoadjuvant chemoradiation therapy in advanced rectal cancer: a national multicenter analysis

BACKGROUND

The aim of the current study was to evaluate the clinical availability of local excision (LE) for advanced rectal cancer without lymph node metastasis after neoadjuvant chemoradiation therapy (nCRT) in Korea.

METHODS

From June 2000 to October 2009, 40 patients with cT2-3N0M0 rectal cancer underwent nCRT followed by LE according to a retrospective multicenter analysis.

RESULTS

Of the 40 patients, 22 were men and 18 were women. Eighteen patients were cT2, and 22 patients were cT3. The median follow-up duration was 38 months. Three patients (7.5%) had morbidity after LE. Four patients (10%) had recurrence (local recurrence [1 patient] and systemic metastasis [3 patients]). The 3-year disease-free survival rate was 85.9%. Only pCR was a recurrence-related prognostic factor (P = .040).

CONCLUSIONS

Although the current study was not a randomized controlled study, LE after nCRT in T2-3N0 rectal cancer patients appears to be a safe and effective treatment, especially in pCR patients.

Early dynamic transcriptomic changes during preoperative radiotherapy in patients with rectal cancer: A feasibility study

AIM: To develop novel biomarkers of rectal radiotherapy, we measured gene expression profiles on biopsies taken before and during preoperative radiotherapy.

METHODS: Six patients presenting with a locally advanced rectal cancer (T>T2, N0/Nx, M0) eligible for preoperative radiotherapy (45 Gy in 25 fractions) were selected in a pilot study. Six tumor and 3 normal tissues biopsies were taken before and during radiotherapy, after a dose of 7.2 Gy at a median time of 1 h following irradiation (0:27-2:12). Tumor or normal tissue purity was assessed by a pathologist prior to RNA extraction. Mean RNA content was 23 μg/biopsy (14-37) before radiotherapy and 22.7 μg/biopsy (12-35) during radiotherapy. After RNA amplification, biopsies were analysed with 54K HG-U133A Plus 2.0 Affymetrix expression micro-arrays. Data were normalized according to MAS5 algorithm. A gene expression ratio was calculated as: (gene expression during radiotherapy - gene expression before radiotherapy)/gene expression before radiotherapy. Were selected genes that showed a ratio higher than ± 0.5 in all 6 patients.

RESULTS: Microarray analysis showed that preoperative radiotherapy significantly up-regulated 31 genes and down-regulated 6 genes. According to the Gene Ontology project classification, these genes are involved in protein metabolism (ADAMDEC1; AKAP7; CAPN5; CLIC5; CPE; CREB3L1; NEDD4L; RAB27A), ion transport (AKAP7; ATP2A3; CCL28; CLIC5; F2RL2; NEDD4L; SLC6A8), transcription (AKAP7; CREB3L1; ISX; PABPC1L; TXNIP), signal transduction (CAPN5; F2RL2; RAB27A; TNFRSF11A), cell adhesion (ADAMDEC1; PXDN; SPON1; S100A2), immune response (CCL28; PXDN; TNFRSF11A) and apoptosis (ITM2C; PDCD4; PVT1). Up-regulation of 3 genes (CCL28; CLIC5; PDCD4) was detected by 2 different probes and up-regulation of 2 genes (RAB27A; TXNIP) by 3 probes.

CONCLUSION: Micro-arrays can efficiently assess early transcriptomic changes during preoperative radiotherapy for rectal cancer, and may help better understand tumor radioresistance.

Radiotherapy response in microsatellite instability related rectal cancer

Preoperative radiotherapy may improve the resectability and subsequent local control of rectal cancers. However, the extent of radiation induced regression in these tumours varies widely between individuals. To date no reliable predictive marker of radiation sensitivity in rectal cancer has been identified. At the cellular level, radiation injury initiates a complex molecular network of DNA damage response (DDR) pathways that leads to cell cycle arrest, attempts at re-constituting the damaged DNA and should this fail, then apoptosis. This review presents the details which suggest the roles of DNA mismatch repair proteins, the lack of which define a distinct subset of colorectal cancers with microsatellite instability (MSI), in the DDR pathways. Hence routine assessment of the MSI status in rectal cancers may potentially serve as a predictor of radiotherapy response, thereby improving patient stratification in the administration of this otherwise toxic treatment.

Prognostic value of microsatellite instability in sporadic locally advanced rectal cancer following neoadjuvant radiotherapy

AIMS

This study was conducted to investigate the clinicopathological significance and prognostic value of microsatellite instability (MSI) in locally advanced rectal cancer (LARC) following neoadjuvant radiotherapy.

METHODS AND RESULTS

A total of 316 consecutive patients with LARC who underwent neoadjuvant radiotherapy and curative surgery were included retrospectively. Microsatellite instability in pretreatment biopsy tissue was assessed using the pentaplex panel of mononucleotides. Twenty-five tumours (7.9%) were assessed as high-frequency MSI (MSI-H) and 291 were low-frequency MSI (MSI-L; n = 42) or microsatellite stable (MSS; n = 249). There were no significant differences in terms of gender, age, tumour location or pretreatment serum carcinoembryonic antigen between the MSI-H and MSI-L + MSS groups. Microsatellite instability was not associated statistically with pathological stage, radiation-induced tumour regression or downstaging. No significant difference was found in disease-free survival (DFS) between the two groups but, within the subgroup of ypN0 stage, patients with MSI-H tumours presented a significantly improved DFS compared with those with MSI-L or MSS tumours (100% versus 79.8%, P < 0.05), whereas no DFS improvement was observed for patients with MSI-H tumours in the ypN + subgroup.

CONCLUSIONS

Microsatellite instability could not predict a histopathological response to neoadjuvant radiotherapy, but was a good prognostic marker for patients without lymph node metastasis after neoadjuvant radiotherapy.

miRNA expressions in rectal cancer as predictors of response to neoadjuvant chemoradiation therapy

INTRODUCTION

Neoadjuvant chemoradiation therapy has been shown to improve the outcome in patients with rectal cancer and is generally accepted as standard care; however, only selected patients would benefit from this treatment. We aimed to identify predictors of response to neoadjuvant chemoradiation therapy in colorectal cancer using formalin-fixed paraffin-embedded (FFPE) tissues as source of genetic materials and microarray analysis as investigation tool.

METHODS

After optimization of RNA extraction methods from FFPE, microarray analysis was carried out on total RNA extracted from 12 pre-treatment FFPE rectal tissues using Megaplex pool A. Microarray data were analysed using an artificial neural network algorithm. Statistical analysis and correlation with clinicopathological data was performed using SPSS software.

RESULTS

A distinct miRNA expression signature predictive of response to neoadjuvant CRT in 12 FFPE pre-treatment rectal cancer tissue samples was identified. These signatures consisted of three miRNA transcripts (miR-16, miR-590-5p and miR-153) to predict complete vs. incomplete response and two miRNA transcript (miR-519c-3p and miR-561) to predict good vs. poor response with a median accuracy of 100 %.

CONCLUSION

Using microarray analysis of pretreatment FFPE rectal cancer tissues, we identified for the first time a group of miRNA predictors of response to neoadjuvant CRT. This, indeed, can lead to a significant improvement in patient selection criteria and personalized rectal cancer management.

Low Mmp 9 and VEGF levels predict good oncologic outcome in mid and low rectal cancer patients with neoadjuvant chemoradiation

Background

The aim of this study was to evaluate apoptotic (Bcl-2, Bax expression, caspase-3 activity, and cytochrome-c) and angiogenic (MMP-9 levels and VEGF expression) markers in operable rectal cancer patients who were treated with preoperative chemoradiotherapy (CRT) followed by total mesorectal excision (TME). Understanding these factors will facilitate the identification of potential pathological responders before treatment, leading to better local control and survival rates.

Methods

Between March 2006 and March 2008, 29 patients withTNM Stage III (cT3 N+) mid or low rectal cancer were included in this study. Our sample consisted of 17 males (58.6%) and 12 females (41.4%). The median age was 60 years (range 24-88 years). Biopsy samples were taken from different portions of the tumors using flexible endoscopy before neoadjuvant CRT. Preoperatively, all patients received radiation (45-50.4 gray (Gy) in 25 cycles with concurrent 5-florouracil (5-FU) chemotherapy.

Results

A complete response was observed in 7 of 29 patients (24%). Bax staining was negative in 1 of the 7 patients (14%) in the pathological complete response (PCR) group and in 18 of the 22 patients (82%) in the no pathological complete response (noPCR) group (p = 0.001). MMP-9 and VEGF levels were higher in the noPCR group than the PCR group (p = 0.04, p = 0.05 respectively). No statistically significant differences were found between VEGF and MMP-9 levels in nodal downstaging. No statistically significant relationships were found between the other apoptotic factors (Bcl 2, cytochrome-c, and caspase-3 activity) and pathological response rate (p > 0.05).

Conclusion

In neoadjuvant CRT patients, high levels of Bax expression and low levels of VEGF and MMP-9 expression on preoperative biopsies indicate that the patient will potentially be a good pathological responder.

Response of glutathione S-transferase Pi (GSTP1) to neoadjuvant therapy in rectal adenocarcinoma

AIM

The response of rectal adenocarcinoma to neoadjuvant therapy is variable. Accurate prediction of response would enable selective administration of therapy. The enzyme glutathione S-transferase Pi (GSTP1) has been shown to influence response to therapy in some solid tumours. Few data are available for rectal cancer.

METHOD

The GSTP1 levels in rectal adenocarcinoma and adjacent normal mucosa were quantified before and after exposure to neoadjuvant therapy. Venous blood samples and biopsies of normal rectal mucosa and tumour were prospectively obtained from patients with primary rectal cancer. Patients were stratified by exposure to neoadjuvant therapy or surgery alone. GSTP1 was quantitatively measured using an enzyme-linked immunosorbent assay.

RESULTS

Ninety-two patients (54 men; median age 68 years) were recruited. The median GSTP1 level was significantly higher in rectal adenocarcinoma than in matched normal mucosa [6.59 μg/mg vs 4.57 μg/mg; P < 0.001]. The median tumour GSTP1 level was significantly lower in the therapy group compared with unmatched samples from the no-therapy group [4.47 μg/mg vs 7.76 μg/mg; P < 0.001].

CONCLUSION

The GSTP1 level is increased in rectal adenocarcinoma compared with adjacent normal mucosa. It decreases following neoadjuvant therapy. Future studies correlating pre-therapy GSTP1 levels with pathological response would be of interest.

Rectal cancer: assessment of response to neoadjuvant chemoradiation by dynamic contrast-enhanced MRI

PURPOSE

To assess pretreatment functional and morphological tumor characteristics with magnetic resonance imaging (MRI) in advanced rectal carcinoma and to identify factors predicting response to neoadjuvant chemoradiation.

MATERIALS AND METHODS

In a prospective study, 95 patients with rectal carcinoma underwent dynamic contrast-enhanced MRI before and after chemoradiation. Quantitative parameters were derived from a pharmacokinetic two-compartment model. Tumors were also characterized with regard to mucinous status at pretreatment high-resolution MRI as nonmucinous or mucinous. Response to treatment was defined as a downshift in the local tumor stage.

RESULTS

The parameter k21 (contrast medium exchange rate) was higher at pretreatment MRI in nonmucinous compared with mucinous carcinomas (P < 0.001). The effect of chemoradiation on dynamic MR parameters was higher in nonmucinous carcinomas than in the mucinous subtype (P < 0.001). A higher rate of response to treatment was linked with nonmucinous morphology (P < 0.001). Multivariate analysis revealed an association between mucinous tumor morphology and poor response (odds ratio [95% confidence interval]: 0.113 [0.032-0.395], P < 0.001) as well as an association between a high 75th percentile of k21 and a higher response rate (odds ratio: 1.043 [1.001-1.086], P = 0.019).

CONCLUSION

Functional and morphological parameters of pretreatment MRI can assess tumor characteristics associated with the effectiveness of chemoradiation before treatment initiation.