Impact of adjuvant chemotherapy on outcomes in appendiceal cancer

Background: The impact of using adjuvant chemotherapy following cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) in patients with appendiceal adenocarcinoma is not known. The aim of this study was to assess the impact of adjuvant chemotherapy following complete cytoreduction in patients with appendiceal adenocarcinoma. Methods: Retrospective medical record review of all patients with appendiceal adenocarcinoma treated at our institution between 2006 and 2015. Kaplan-Meier plots were used to summarize overall survival (OS) and relapse-free survival over time, and log-rank tests and Cox proportional hazards models were used to test for differences in survival between groups. Results: A total of 103 patients with appendiceal adenocarcinoma received care at our institution during the study period. Complete cytoreduction (cytoreductive score 0-1) was achieved in 68 patients (66%). Of these 68 patients, 26 received adjuvant chemotherapy. The most common regimens were capecitabine (n = 11), capecitabine plus oxaliplatin (n = 7), and 5-FU plus oxaliplatin (n = 6). Tumor histopathology and grade, and the ability to achieve complete cytoreduction were significant predictors of overall survival. The median OS for non–low-grade and well-differentiated tumor patients who received adjuvant chemotherapy following complete cytoreduction was 9.03 years, compared to 2.88 years for patients who did not receive adjuvant chemotherapy (P =.02). Among low-grade and well-differentiated tumor patients who underwent complete cytoreduction, there was no statistically significant difference in OS between those who received adjuvant chemotherapy and those who did not. Conclusion: Adjuvant chemotherapy seems to have benefit in appendiceal cancer patients with non–low-grade or well-differentiated tumor type but not in low-grade or well-differentiated tumors.