Magnetic Resonance Imaging-Detected High-Risk Markers in Rectal Cancer Patients With a Pathologic Complete Response After Neoadjuvant Therapy.

Abstract

Pathologic complete response (pCR) is a surrogate end point for prognosis in rectal cancer, yet a subset of pCR patients still face recurrence or poor outcomes. The identification of high-risk pCR patients and the effectiveness of adjuvant therapy remain contentious. This study aimed to evaluate pretreatment magnetic resonance imaging (MRI) markers, identify high-risk pCR patients, and assess the benefit of adjuvant therapy. This retrospective multicenter study analyzed 384 pCR patients (2010-2019) to assess pretreatment MRI markers' prognostic value. Disease-free survival (DFS) and overall survival (OS) were estimated using Kaplan-Meier curves, with group differences evaluated via the log-rank test. Among the MRI markers evaluated, magnetic resonance with tumor deposits (mrTD) emerged as the strongest prognostic factor. Positive mrTD was associated with a five-fold increased risk of recurrence (adjusted hazard ratio, 5.16 [95% CI, 2.67 to 9.97]; <i>P</i> < .001) and significantly reduced OS (5.04 [1.80 to 14.1]; <i>P</i> = .002). Patients with mrTD⁺ had a 3-year DFS of 74.5% and a 5-year OS of 83.6%, compared with 96.6% and 98.6%, respectively, in mrTD^- patients. Notably, adjuvant therapy did not improve prognosis in pCR patients, regardless of their MRI marker status. Positive mrTD is a critical prognostic marker in pCR patients. Adjuvant therapy did not confer benefits, highlighting the need for personalized treatment strategies.