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Molecular diagnosis of response to neoadjuvant chemoradiation therapy in patients with locally advanced rectal cancer.

ABSTRACT: Pathologic complete response (pCR) to neoadjuvant chemoradiation (CRT) is an important prognostic factor in locally advanced rectal cancer. However, it is uncertain if histopathological techniques accurately detect pCR. We tested a novel molecular approach for detecting pCR and compared it with current histopathological approaches.Pretreatment tumor biopsies and surgical specimens were collected from 96 patients with locally advanced rectal cancer treated with neoadjuvant CRT and surgery. Tumor response was categorized by tumor regression grade. Tumor DNA from pre-CRT tumor biopsies was screened for K-ras and p53 mutations. DNA from paired surgical specimens was then screened for the same mutations using highly sensitive polymerase chain reaction-based techniques.Sixty-eight of 96 (71%) pretreatment biopsies harbored K-ras and/or p53 mutation; 36 (38%) had K-ras mutations, 52 (54%) had p53 mutations, and 20 (21%) carried both mutations. Of 70 patients with tumor regression grades 1 to 3, sixty-six (94%) had a concordant K-ras and p53 mutation profile in pre- and post-treatment tissues. Of 26 patients with tumor regression grade 0 (pCR), 12 had K-ras or p53 mutations in pretreatment biopsies. Of these, 2 (17%) patients had the same K-ras (n = 1) or p53 (n = 1) mutation detected in post-treatment tissue.Sensitive molecular techniques detect K-ras and p53 mutations in post-CRT surgical specimens in some patients with a pCR. This suggests histopathological techniques might not be completely accurate, and some patients diagnosed with a pCR to CRT might have occult cancers cells in their surgical specimens.

SUBMITTER: Chen Z

PROVIDER: S-EPMC3104075 | biostudies-literature | 2011 Jun

REPOSITORIES: biostudies-literature

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Molecular diagnosis of response to neoadjuvant chemoradiation therapy in patients with locally advanced rectal cancer.

Chen Zhenbin Z Duldulao Marjun P MP Li Wenyan W Lee Wendy W Kim Joseph J Garcia-Aguilar Julio J

Journal of the American College of Surgeons 20110331 6

<h4>Background</h4>Pathologic complete response (pCR) to neoadjuvant chemoradiation (CRT) is an important prognostic factor in locally advanced rectal cancer. However, it is uncertain if histopathological techniques accurately detect pCR. We tested a novel molecular approach for detecting pCR and compared it with current histopathological approaches.<h4>Study design</h4>Pretreatment tumor biopsies and surgical specimens were collected from 96 patients with locally advanced rectal cancer treated ...[more]

PMID: 21458303

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Project description:Background:There is recent interest in treating locally advanced rectal cancer (LARC) patients with total neoadjuvant therapy (TNT). However, whether TNT is associated with improved overall survival (OS) remains unknown. This study compares outcomes following TNT and following neoadjuvant chemoradiation therapy (nCRT) in patients with LARC, clinically defined cT3/4 or node positive disease, using the National Cancer Database. Methods:LARC patients diagnosed between 2004-2015 were included. TNT was defined as multi-agent chemotherapy given at least 2 months before RT followed by pre-operative chemoradiation therapy and definitive surgery without adjuvant chemotherapy. nCRT was defined as pre-operative RT and chemotherapy started within 2 weeks from each other followed by definitive surgery with or without adjuvant chemotherapy. Kaplan-Meier curve with logrank test and multivariable Cox proportional hazards regression modelling were used to analyse the primary endpoint of overall survival (OS). Multivariable logistic regression modelling was used for secondary outcomes to determine if TNT is associated with pathological complete response (pCR), defined as ypT0N0, and negative circumferential resection margin (CRM). Findings:Data from 372 TNT patients and 707 nCRT patients were analysed after a 2:1 propensity matching with replacement. Kaplan-Meier curve showed that OS with TNT was comparable to that with nCRT (p = 0•16). The 5-year OS rates for TNT and nCRT were 73•6% vs. 78•5% (p = 0•20). Multivariable Cox proportional hazards regression modelling confirmed no difference in OS between TNT and nCRT (HR = 1•21, p = 0•25). With TNT, 16•9% patients achieved pCR, whereas 13•1% patients achieved pCR with nCRT (p = 0•12). TNT was not found to be significantly associated with pCR (OR = 1•36, p = 0•13) or negative CRM (OR = 1•77, p = 0•19) in multivariable logistic regression modelling. Interpretation:With results from current clinical trials pending, our data suggested that TNT and nCRT resulted in similar survival, while TNT led to higher pCR and CRM negative rate, albeit not statistically significant.

Project description:ImportanceTreatment of locally advanced rectal (LARC) cancer involves chemoradiation, surgery, and chemotherapy. The concept of total neoadjuvant therapy (TNT), in which chemoradiation and chemotherapy are administered prior to surgery, has been developed to optimize delivery of effective systemic therapy aimed at micrometastases.ObjectiveTo compare the traditional approach of preoperative chemoradiation (chemoRT) followed by postoperative adjuvant chemotherapy with the more recent TNT approach for LARC.Design, setting, and participantsA retrospective cohort analysis using Memorial Sloan Kettering Cancer Center (MSK) records from 2009 to 2015 was carried out. A total of 811 patients who presented with LARC (T3/4 or node-positive) were identified.ExposuresOf the 811 patients, 320 received chemoRT with planned adjuvant chemotherapy and 308 received TNT (induction fluorouracil- and oxaliplatin-based chemotherapy followed by chemoRT).Main outcomes and measuresTreatment and outcome data for the 2 cohorts were compared. Dosing and completion of prescribed chemotherapy were assessed on the subset of patients who received all therapy at MSK.ResultsOf the 628 patients overall, 373 (59%) were men and 255 (41%) were women, with a mean (SD) age of 56.7 (12.9) years. Of the 308 patients in the TNT cohort, 181 (49%) were men and 127 (49%) were women. Of the 320 patients in the chemoRT with planned adjuvant chemotherapy cohort, 192 (60%) were men and 128 (40%) were women. Patients in the TNT cohort received greater percentages of the planned oxaliplatin and fluorouracil prescribed dose than those in the chemoRT with planned adjuvant chemotherapy cohort. The complete response (CR) rate, including both pathologic CR (pCR) in those who underwent surgery and sustained clinical CR (cCR) for at least 12 months posttreatment in those who did not undergo surgery, was 36% in the TNT cohort compared with 21% in the chemoRT with planned adjuvant chemotherapy cohort.Conclusions and relevanceOur findings provide additional support for the National Comprehensive Cancer Network (NCCN) guidelines that categorize TNT as a viable treatment strategy for rectal cancer. Our data suggest that TNT facilitates delivery of planned systemic therapy. Long-term follow-up will determine if this finding translates into improved survival. In addition, given its high CR rate, TNT may facilitate nonoperative treatment strategies aimed at organ preservation.

Project description:Purpose: Intratumoral genetic heterogeneity (ITGH) is a common feature of solid tumors. However, little is known about the effect of neoadjuvant chemoradiation (nCRT) in ITGH of rectal tumors that exhibit poor response to nCRT. Here, we examined the impact of nCRT in the mutational profile and ITGH of rectal tumors and its adjacent irradiated normal mucosa in the setting of incomplete response to nCRT. Methods and Materials: To evaluate ITGH in rectal tumors, we analyzed whole-exome sequencing (WES) data from 79 tumors obtained from The Cancer Genome Atlas (TCGA). We also compared matched peripheral blood cells, irradiated normal rectal mucosa and pre and post-treatment tumor samples (PRE-T and POS-T) from one individual to examine the iatrogenic effects of nCRT. Finally, we performed WES of 7 PRE-T/POST-T matched samples to examine how nCRT affects ITGH. ITGH was assessed by quantifying subclonal mutations within individual tumors using the Mutant-Allele Tumor Heterogeneity score (MATH score). Results: Rectal tumors exhibit remarkable ITGH that is ultimately associated with disease stage (MATH score stage I/II 35.54 vs. stage III/IV 44.39, p = 0.047) and lymph node metastasis (MATH score N0 35.87 vs. N+ 45.79, p = 0.026). We also showed that nCRT does not seem to introduce detectable somatic mutations in the irradiated mucosa. Comparison of PRE-T and POST-T matched samples revealed a significant increase in ITGH in 5 out 7 patients and MATH scores were significantly higher after nCRT (median 41.7 vs. 28.8, p = 0.04). Finally, we were able to identify a subset of "enriched mutations" with significant changes in MAFs between PRE-T and POST-T samples. These "enriched mutations" were significantly more frequent in POST-T compared to PRE-T samples (92.9% vs. 7.1% p < 0.00001) and include mutations in genes associated with genetic instability and drug resistance in colorectal cancer, indicating the expansion of tumor cell subpopulations more prone to resist to nCRT. Conclusions: nCRT increases ITGH and may result in the expansion of resistant tumor cell populations in residual tumors. The risk of introducing relevant somatic mutations in the adjacent mucosa is minimal but non-responsive tumors may have potentially worse biological behavior when compared to their untreated counterparts. This was an exploratory study, and due to the limited number of samples analyzed, our results need to be validated in larger cohorts.

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Molecular diagnosis of response to neoadjuvant chemoradiation therapy in patients with locally advanced rectal cancer.

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Molecular diagnosis of response to neoadjuvant chemoradiation therapy in patients with locally advanced rectal cancer.

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