A proposal of an updated classification for pelvic relapses of rectal cancer to guide surgical decision-making

Background and Objectives Selection of patients affected by pelvic recurrence of rectal cancer (PRRC) who are likely to achieve a R0 resection is mandatory. The aim of this study was to propose a classification for PRRC to predict both radical surgery and disease-free survival (DFS). Methods PRRC patients treated at the National Cancer Institute of Milan (Italy) were included in the study. PRRC were classified as S1, if located centrally (S1a-S1b) or anteriorly (S1c) within the pelvis; S2, in case of sacral involvement below (S2a) or above (S2b) the second sacral vertebra; S3, in case of lateral pelvic involvement. Results Of 280 reviewed PRRC patients, 152 (54.3%) were evaluated for curative surgery. The strongest predictor of R+ resection was the S3 category (OR, 6.37; P = .011). Abdominosacral resection (P = .012), anterior exenteration (P = .012) and extended rectal re-excision (P = .003) were predictive of R0 resection. S3 category was highly predictive of poor DFS (HR 2.53; P = .038). DFS was significantly improved after R0 surgery for S1 (P < .0001) and S2 (P = .015) patients but not for S3 cases (P = .525). Conclusions The proposed classification allows selection of subjects candidates to curative surgery, emphasizing that lateral pelvic involvement is the main predictor of R+ resection and independently affects the DFS.