Outcomes of exenteration in cT4 and fixed cT3 stage primary rectal adenocarcinoma: a subgroup analysis of consolidation chemotherapy following neoadjuvant concurrent chemoradiotherapy.

Purpose: The aim was to evaluate the oncological outcomes and the prognostic factors following pelvic exenteration (PE) in cT4 and fixed cT3 stage primary rectal adenocarcinoma and to study the impact of consolidation chemotherapy following neoadjuvant concurrent chemoradiotherapy (NACRT).

Methods: A retrospective analysis of a prospectively maintained database of PE from 2013 to 2018.

Results: Out of 2900 colorectal resections, there were 131 pelvic exenterations that were performed, and 100 of these patients had undergone exenteration for primary rectal adenocarcinoma. Of these 100 patients, there were 81 patients who had received NACRT followed by surgery, 50 of whom who had received consolidation chemotherapy and 31 who had undergone surgery without consolidation chemotherapy. R0 resection was achieved in 90% cases. At a median follow-up of 32 months, 2-year disease free survival was 61.8% and estimated 5-year overall survival was 62%. The incidence of distant metastases was 44% vs. 19% (p = 0.023), and the 2-year distant recurrence-free survival was 58% vs. 89% (p = 0.025), respectively, in the 'consolidation chemotherapy group' and the 'no chemotherapy group'. The poorly differentiated grade of tumours, presence of lympho-vascular-invasion, consolidation chemotherapy, and disease recurrence were all found to affect the survival.

Conclusion: PE with R0 resection achieves excellent survival rates in cT4 and fixed cT3 stage primary rectal adenocarcinoma. The distant recurrence rate may not be altered by consolidation chemotherapy in the subset of high-risk patients. However, further research on consolidation chemotherapy following NACRT in cT4 and fixed cT3 stage primary rectal adenocarcinoma will give a definite answer in the future.