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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: PURPOSE, METHODS AND MATERIALS, RESULTS. Meshes: Adult, Aged, Aged, 80 and over, Analysis of Variance, Antimetabolites, Antineoplastic, Combined Modality Therapy, Disease-Free Survival, Female, Fluorouracil, Follow-Up Studies, Humans, Leucovorin, Male, Middle Aged, Mitomycin, Neoadjuvant Therapy, Neoplasm Recurrence, Local, Neoplasm Staging, Neoplasm, Residual, Radiotherapy Dosage, Rectal Neoplasms, Survival Rate.
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Can histopathologic assessment of circumferential margin after preoperative pelvic chemoradiotherapy for T3-T4 rectal cancer predict for 3-year disease-free survival? Context: This study set out to determine the impact of a positive circumferential resection margin (CRM) (R1-R2) and pathologic downstaging on local recurrence and survival in patients with borderline resectable or unresectable rectal adenocarcinoma treated with neoadjuvant chemoradiotherapy (CRT). A total of 150 patients with locally advanced rectal cancer were treated with long-course neoadjuvant CRT using low-dose folinic acid and 5-fluorouracil. CRT was followed 6-12 weeks later by surgical excision. The CRM rate and incidence, site, and pattern of local and systemic recurrences were recorded. The median follow-up was 25 months. The overall median survival was 37 months, with a 5-year overall survival rate of 34%. Of the 150 patients, 122 underwent curative resection; 12% had a complete pathologic response, and downstaging to pT1-T2 occurred in an additional 16%. A negative CRM (R0) was achieved in 65% overall (98 of 150). Local recurrence occurred in 10% of those with R0 resection and 62% of those with R1-R2 resections. Distant metastases occurred in 29% of those with R0 resections and 75% of those with R1-R2 resections. The 3-year disease-free and 3-year overall survival rate was 9% and 25% and 52% and 64%, respectively, for patients with and without a histologically positive CRM.
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After 5-fluorouracil-based CRT, a positive CRM predicted for a high risk of subsequent local recurrence and a 3-year disease-free survival rate of only 9%. For this reason, the CRM should be considered a major prognostic factor and should be validated in future trials as an early alternative clinical endpoint.