Effect of adjuvant chemotherapy after curative resection of colorectal cancer peritoneal metastasis.

PURPOSE: Several guidelines have recommended surgical resection for localized peritoneal metastases, but the prognosis remains poor. In addition, the efficacy of adjuvant chemotherapy (AC) after curative resection is under debate. The present study compared long-term outcomes between curative and non-curative resection and evaluated the effects of AC after curative resection.

METHODS

Using a multicenter database, we retrospectively reviewed 123 colorectal cancer patients with peritoneal metastases between April 2016 and December 2021. Of these patients, 49 underwent curative resection, and 74 underwent non-curative resection.

RESULTS

The frequency of broad metastases was lower in the curative resection group (8.2%) than in the non-curative resection group (43.2%, p < 0.001). Among all patients, 5-year overall survival rate was higher in the curative resection group (43.0%) than in the non-curative resection group (7.3%, p = 0.004). Among patients who underwent curative resection, 5-year overall survival rate was significantly higher in the AC group (48.2%) than in the non-AC group (38.1%, p = 0.037). Multivariate analysis of all patients revealed pathological N status and non-curative resection as independent predictors of overall survival. In patients who underwent curative resection, advanced age was an independent predictor of relapse-free survival, and AC was an independent predictor of overall survival.

CONCLUSION

This multicenter study of colorectal cancer patients with peritoneal metastases revealed that prognosis was more favorable for curable cases than for non-curable cases. Prognosis was more favorable in the AC group than in the non-AC group after curative resection.