Pathologic complete response after neoadjuvant chemotherapy/(re)chemoradiation for pelvic relapse of rectal cancer undergoing complex pelvic surgery: more frequent than expected?

Purpose To estimate the rate of pathologic complete response (pCR) after neoadjuvant chemotherapy/(re)chemoradiation and its impact on survival in locally recurrent rectal cancer (LRRC) and to identify predictors of pCR or differences between neoadjuvant treatments. Methods Among 394 LRRC patients treated at the National Cancer Institute of Milan (Italy), 74 (27.8%) were treated with neoadjuvant chemotherapy with or without (re)chemoradiation before surgery. The pCR rate was estimated, and its impact on 5-year survival was evaluated with the Kaplan-Meier survival method. Univariate analysis was performed to find pre-treatment predictors of pCR. Results After surgery, in 12 (16.2%) patients, a pCR was observed. All patients who reached pCR had R0 margins after surgery; among the 62 non-pCR patients, R0 margins were obtained in 29 (46.8%) cases only (p = 0.0004). pCR patients showed a significantly higher 5-year overall survival compared to non-pCR cases (33.3% vs. 21.0%, p = 0.045) and a trend toward better 5-year re-local recurrence-free survival. On univariate analysis, no predictor of pCR was found in the present study based on pre-treatment features. Conclusion Since pCR is significantly associated to R0 resection and 5-year overall survival, pCR could be a target for LRRC cure. However, pCR is currently unpredictable based on pre-treatment features.

Automated summary

This study aims to evaluate the rate of pathologic complete response (pCR) in locally recurrent rectal cancer (LRRC) after neoadjuvant chemotherapy/(re)chemoradiation, and its impact on survival. The results show that achieving pCR is associated with better overall survival and R0 margins. However, predicting pCR based on pre-treatment features is currently not possible.