Background/aims: To investigate the recurrence patterns and interval from initial surgery in patients with curatively resected colorectal cancer followed for a minimum of 10 years.
Methodology: We retrospectively reviewed 418 patients who had undergone curative resection for colon cancer (n = 246) or rectal cancer (n = 169). Follow-up periods ranged from 10 to 23 years. Main outcome measures were interval until recurrence, site of first recurrence, and influence of adjuvant chemotherapy.
Results: 26 (6%) had been lost to follow-up by 10 years and 143 (34%) had died. The most common site of recurrence was liver in colon cancer and locoregional in rectal cancer. The cumulative recurrence rate in colon cancer was 100% at 4 years. In rectal cancer, it was 89% at 5 years, 98% at 7 years and 100% at 10 years. The interval until recurrence was longer in rectal cancer (26.0 +/- 24.2 months) than in colon cancer (17.1 +/- 11.0 months) (p = 0.03). It was also longer in patients receiving than in those not receiving adjuvant chemotherapy (p < 0.01). The interval until lung metastasis was longer than that until liver metastasis in colon cancer (p = 0.04), and longer than that until locoregional recurrence in rectal cancer (p = 0.03). The interval until recurrence in the colon cancer was shorter for stage III than for stage II (p = 0.02).
Conclusions: Surveillance for recurrences, particularly for relapses in the liver and lung, should be performed for at least 4 years in colon cancer patients. Patients with rectal cancer should be followed for a longer period than those with colon cancer, focusing on locoregional, liver and lung recurrence. It is particularly noteworthy that adjuvant chemotherapy may prolong the interval until recurrence and the interval until lung metastasis is relatively longer.