Impact of chemotherapy-related prognostic factors on long-term survival in patients with stage III colorectal cancer after curative resection.

Background: This retrospective study evaluated the prognostic factors of chemotherapy in stage III colorectal cancer after curative resection.
Methods: From 1996 to 2001, 1,054 patients with primary single colorectal cancer underwent curative resection. Seven hundred sixteen patients received various 5-fluorouracil (FU)-based adjuvant chemotherapy regimens, including oral and intravenous treatments. The chemotherapy-related parameters examined included therapeutic duration, frequency, route of administration, composition of combination therapies, and postoperative time interval from the operation to the start of chemotherapy.
Results: The therapeutic duration and postoperative time interval of starting therapy were independent prognostic factors, in addition to clinicopathological factors. The 8-year cancer-specific/overall survival rates in patients who received chemotherapy for >4 months (63.0/58.6%) were significantly higher than the rates in patients who received no chemotherapy (56.7/37.7%, P < 0.01) and those who remained on chemotherapy for 1-4 months (49.4/41.9%, P < 0.05). The 8-year cancer-specific/overall survival rates in patients who waited 1-5 weeks after surgery to receive chemotherapy (62.9/58.5%) were significantly higher versus rates in those who did not receive chemotherapy (56.7/37.7%) and those who did not receive chemotherapy until >5 weeks after surgery (52.3/45.9%) (both P < 0.05). Survival rates did not differ between patients who did not undergo chemotherapy, those for whom chemotherapy lasted 1-4 months, and patients who did not receive chemotherapy until >5 weeks after surgery.
Conclusions: The appropriate duration of therapy and early chemotherapy after surgery were 2 of the most important factors in eradicating occult cancer and effecting long-term survival benefits in patients with stage III colorectal cancer.