Operative trends following the adoption of nonoperative management of rectal cancer.

Background: Differentiating clinical near-complete and complete responses (cCR) after neoadjuvant therapy (NT) is challenging in rectal cancer patients. We hypothesized that magnetic resonance imaging staging limitations for low rectal cancers may increase the proportion of abdominoperineal resection (APR) with permanent colostomy for those without a cCR.

Methods: Single institution retrospective analysis of rectal cancer cases before and after adoption of nonoperative "watch and wait" (W&W) pathway. APR as a percentage of rectal resections was the primary outcome.

Results: There were 76 total mesorectal excisions (TME) in the pre-W&W group and 98 in the post-W&W group. NT was significantly more common in the post-W&W group. There was no significant difference in the APR primary outcome (pre-W&W APR 33.3% vs. post-W&W APR 26.5%, p = 0.482). APR patients had fewer complete TME grades (69.2% vs. 46.2%) and more pathologic complete responses (0% vs. 26.9%) in the post-W&W period. The cCR rate for patients with nonoperative management was 51.4% (n = 37) and 13.5% (n = 5) had regrowths, all of whom underwent salvage surgery.

Conclusion: APR for those without a cCR to NT has not increased in the nonoperative management era. Balancing the pathologic complete response rate may require restaging some patients with clinical near-complete responses.