Word of caution: Rectal cancer without response to neoadjuvant treatment - Do not wait for surgery.

Background: We hypothesized that prolonging the interval to surgery in non-responders to neoadjuvant chemoradiation therapy (nCRT) could lead to worse oncologic outcomes.

Methods: Rectal adenocarcinoma patients with poor tumor response to nCRT (AJCC tumor regression grade 3) were selected. Oncologic outcomes were evaluated according to the time interval between completion of nCRT and surgery.

Results: Among 56 non-responders, 28 patients surgically treated ≥8 weeks after completion of nCRT had worse disease-free survival (31% vs. 49%, p ​= ​0.05) and worse overall survival (34% vs. 53%, p ​= ​0.02) compared to patients <8 weeks. Using the three different intervals (≥12 weeks, 6-12 weeks, and< 6 weeks), waiting longer was consistently associated with worse overall (23% vs. 48% vs. 63%, p ​= ​0.02) and worse cancer-specific survival (35% vs. 61% vs. 71%, p ​= ​0.04), respectively.

Conclusion: For rectal cancer patients who are non-responders to nCRT, delay of surgery may lead to worse oncologic outcomes.