Abstract
BACKGROUND: Locally advanced rectal cancer (LARC) requires a multimodal therapy tailored to the patient and tumor characteristics. Pretreatment magnetic resonance imaging (MRI) is necessary to stage the primary tumor, while restaging MRI, which is not systematically performed, may be of interest to identify poor responders to neoadjuvant chemoradiation therapy (NCRT), and redefine therapeutic approach. The EuMaRCS study group aimed to investigate the role and accuracy of pretreatment (including pelvimetry) and restaging MRIs in predicting surgical difficulties and surgical outcomes in LARC therapy. METHODS: Patients with mid or low LARC who were administered NCRT, who underwent laparoscopic total mesorectal excision, and for whom pretreatment and restaging MRIs were available, were included. RESULTS: MRIs of 170 patients (median age: 61 years) were reanalyzed by the same radiologist. Pelvimetry differed significantly between males and females, but no gender difference was noted in the clinical and tumor characteristics. Tumor volume and tumor height assessed on the restaging MRI were associated, respectively, with operative time and estimated blood loss. Conversion was predicted by tumor volume, interischial distance and pubic tubercle height. The quality of the surgical resection was found to be a predictor of overall and disease-free survival. The sensitivity and specificity of tumor regression grade 1 to identify a pathologic complete response were 76.9% and 89.3%, respectively. CONCLUSIONS: In LARC management, pelvimetry and restaging MRI may be useful to predict surgical difficulties and surgical outcomes. However, the main independent predictor of patient survival appears to be the achievement of a successful surgical resection.