Association Between Time (Initiation and Length) and Oncological Outcomes for the Patients with Colon Cancer Treated with Adjuvant Chemotherapy.

Adjuvant chemotherapy is benefit for high-risk stage II and stage III colon cancer after curative resection. But, the optimal time between surgical and initiation of adjuvant chemotherapy remains unclear. Moreover, no study of efficacy with different lengths of adjuvant chemotherapy has appeared. This study was aimed to identify association between time (initiation and length) and oncological outcomes of adjuvant chemotherapy on the stages II and III colon cancer patients. A total of 406 high-risk stages II and III colon cancer patients were retrospectively enrolled in prospectively collected data. They were categorized into three groups representing chemotherapy initiation time: less than 4 weeks (group 1), 4 to 6 weeks (group 2), and more than 6 weeks (group 3). They were categorized into two groups representing chemotherapy length time : less than 200 days (group 1a) and more than 200 days (group 2a). The 5-year disease-free survival (DFS) rates were 74.97 % in group 1, 76.94 % in group 2, and 63.97 % in group 3 (p > 0.05). The 5-year DFS rates were 75.49 % in the group that received adjuvant chemotherapy within 6 weeks and 63.97 % in the group that received adjuvant chemotherapy >6 weeks (p = 0.0539). The 5-year DFS rates were 77.21 % in group 1a and 81.82 % in group 2a (p > 0.05). Adjuvant chemotherapy should be safely offered within 6 weeks after surgical excision in patients with colon cancer after considering the patient's general physical condition and hematological factors, even if the chemotherapy length is prolonged.