Study: Starting adjuvant chemotherapy more than 6 weeks after surgery worsens colorectal cancer survival

Editor's Note

A post hoc analysis of the SCOT phase 3 randomized clinical trial reveals that initiating adjuvant chemotherapy more than 6 weeks after surgery is linked to worse disease-free survival (DFS) in patients with high-risk stage II and stage III colorectal cancer.

Published June 12 in JAMA Surgery, the study included 5,719 patients from six countries, found that patients who started chemotherapy within 6 weeks of surgery had a 5-year DFS rate of 78.0%, compared to 73.2% for those who started later. The analysis adjusted for factors like age, sex, and tumor stage, confirming that delayed chemotherapy was independently associated with a higher risk of recurrence or death (HR 1.24; 95% CI, 1.06-1.46; P = .01).

Interestingly, the timing of chemotherapy did not affect the occurrence of adverse events, either during the entire treatment period or the first cycle. The findings underscore the importance of timely chemotherapy initiation, suggesting that starting treatment within 6 weeks could improve long-term outcomes without increasing treatment-related risks. These results align with European Society for Medical Oncology guidelines, which recommend starting adjuvant chemotherapy within 8 weeks of surgery, but the data from this analysis suggest an even earlier start may be more beneficial.

Given the study's international scope and prospective data collection, these findings provide strong evidence for prioritizing early chemotherapy post-surgery to enhance DFS in colorectal cancer patients.