Purpose: Early detection of recurrence after curative resection for primary colorectal cancer should improve patients' prognosis. However, the usefulness of postoperative surveillance programs has not been clarified yet. The present cohort study was aimed at assessing the effectiveness of systematic follow-up in patients with colorectal cancer who were operated on for cure, regarding both rate of tumor recurrence amenable to curative-intent surgery and rate of survival.
Methods: One hundred ninety-nine colorectal cancer patients who underwent radical primary surgery were followed according a well-defined postoperative surveillance program, which consisted of laboratory studies (including serum carcinoembryonic antigen assay) every three months, physical examination and abdominal ultrasound or computed tomography every six months, and chest radiograph and total colonoscopy once per year. Cohorts were defined according to patients' compliance with the proposed follow-up program. A multivariate regression model was constructed to predict survival.
Results: One hundred forty patients were considered to be compliant with the surveillance program, whereas the remaining 59 patients occasionally attended follow-up investigations or did not comply at all. Although there were no differences in the overall recurrence rate (38 vs. 41 percent; P = 0.52), curative-intent reoperation was possible in 18 patients (34 percent) of those with tumor recurrence in the compliant cohort but in only 3 patients (12 percent) in the noncompliant cohort (P = 0.05). Similarly, the probability of survival was higher in the compliant cohort, both regarding overall (63 vs. 37 percent at 5 years; P < 0.001) and cancer-related (69 vs. 49 percent at 5 years; P < 0.02) rates. Cox regression analysis disclosed that only a more advanced TNM stage (odds ratio, 8.17; 95 percent confidence interval, 1.13-59.29) and noncompliance with the postoperative surveillance program (odds ratio, 2.32; 95 percent confidence interval, 1.50-3.60) had an independent negative impact on survival.
Conclusion: Systematic postoperative surveillance in patients with colorectal cancer who were operated on for cure increases both the rate of tumor recurrence amenable to curative-intent surgery and rate of survival.