Pathologic response assessed by Mandard grade is a better prognostic factor than down staging for disease‐free survival after preoperative radiochemotherapy for advanced rectal cancer

Abstract

The reduction in tumour stage induced by full course radiotherapy plus chemotherapy is apparent from histological changes. The purpose of this study was to determine the rate of complete pathological response and to evaluate the prognostic value for disease free survival (DFS) and disease specific survival (DSS) of the response. The relation between pretreatment variables (age, gender, stage, tumour height and [carcinoembryogenic antigen (CEA)] and postsurgical variables was compared to the pathological response. A total of 119 patients with stage II or III rectal cancer underwent surgery 6 weeks after neoadjuvant treatment. Group A included patients with a complete or good pathological response (Mandard grade I-II) and group B patients with a poor response (Mandard grade III-IV-V). The pretreatment endo-rectal ultrasound scan stage was compared with histopathology stage of the resected specimen. DFS and DSS were compared using the log-rank test. All 119 patients (mean age 67.9 years, 83 males) underwent resection. The tumour was located in the upper, middle and lower third of the rectum in 11, 51 and 57 patients. 88 patients had a low anterior resection, 28 patients abdomino-perineal resection and three a Hartmann's operation. There was no postoperative death. The circumferential margin (CM) was involved in 10%. A complete pathological response was observed in 17 (14.2%) patients. Thirty-six (30.2%) patients had a group A and 83 a group B response. Group A showed DFS to be significantly higher than group B (log rank: P = 0.007). The DSS rate was not significantly different between the two groups (log rank P = 0.113). Down-staging was not related with DFS. No relation was found between pretreatment variables and response. A good pathological response was related to a lower rate of permanent colostomy but not with CM involvement or the number of lymph nodes. Tumour regression of grades I or II was a good indicator of DFS in locally advanced rectal cancer, treated by neoadjuvant chemotherapy and radiotherapy. Patients with a high regression grade were associated with a lower incidence of definitive stoma formation. The regression grade was shown to be a better prognostic factor than down-staging.