MRI assessment and outcomes in patients receiving neoadjuvant chemotherapy only for Primary Rectal Cancer : longterm results from the GEMCAD 0801 trial
Mené sur 46 patients atteints d'un cancer rectal et ayant reçu une chimiothérapie néoadjuvante à base de capécitabine, d'oxaliplatine et de bévacizumab (durée médiane de suivi : 41 mois), cet essai identifie des paramètres histopathologiques, mesurés par IRM, pour prédire la survie sans maladie et le risque de récidive
Background : Primary chemotherapy has been tested as a possible approach for patients with high risk features but predicted clear mesorectal margins on preoperative MRI assessment.This study investigates the prognostic relevance of baseline and post-treatment MRI and pathology staging in rectal cancer patients undergoing primary chemotherapy.
Patients and Methods : Forty-six patients with T3 tumour>1mm from the mesorectal fascia were prospectively treated with Neoadjuvant Capecitabine,Oxaliplatin and Bevacizumab prior to surgery between 2009-11.The baseline and post-treatment MRI: T, Nodal and Extra-mural venous invasion(EMVI) status were recorded as well as post-treatment MRI Tumour regression grade(TRG) and modified-RECIST assessment of tumour length. The post-treatment pathology(yp) assessments of T3 substage, N,EMVI and TRG status were also recorded. Three-year disease free survival(DFS) and cumulative incidence of recurrence were estimated by using the Kaplan-Meier product-limit method, and Cox proportional hazards models were used to determine associations between staging and response on MRI and pathology with survival outcomes.
Results : 46 patients underwent neoadjuvant chemotherapy alone for high risk margin safe primary rectal cancer. The median follow-up was 41 months, 5 patients died and 11 patients experienced relapse (2local,8distant,1both). In total 23/46 patients were identified with MRI features of EMVI at baseline. mrEMVI positive status carried independent prognostic significance for DFS(p=0.0097) with a hazard ratio of 31.33(95%CI 2.3-425.4). The histopathologic factor that was of independent prognostic importance was a final ypT downstage of ypT3a or less, Hazard Ratio: 14.0(95%CI 1.5-132.5).
Conclusions : mrEMVI is an independent prognostic factor at baseline for poor outcomes in rectal cancer treated with neoadjuvant chemotherapy whilst ≤ypT3a is associated with an improvement in DFS. Future preoperative therapy evaluation in rectal cancer patients will need to stratify treatment according to baseline EMVI status as a crucial risk factor for recurrence in patients with predicted CRM clear rectal cancer.
Annals of Oncology , résumé, 2016