BACKGROUND: Most previous reports to analyze risk factors for peritoneal recurrence in patients with colon cancer have been observational studies of a population-based cohort. OBJECTIVE: This study aimed to determine the risk factors for peritoneal recurrence in patients with stage II to III colon cancer who underwent curative resection. DESIGN: This was a pooled analysis using a combined database obtained from 3 large phase III randomized trials (N = 3714). SETTINGS: Individual patient data were collected from the Japanese Foundation for Multidisciplinary Treatment of Cancer clinical trials 7, 15, and 33, which evaluated the benefts of postoperative 5-fluorouracil-based adjuvant therapies in patients with locally advanced colorectal cancer. PATIENTS: We included patients who had stage II to III colon cancer and underwent curative resection with over D2 lymph node dissection. MAIN OUTCOME MEASURES: Main outcomes measured were risk factors for peritoneal recurrence without other organ metastasis after curative surgery. RESULTS: Peritoneal recurrence occurred in 2.3% (86/3714) of all patients undergoing curative resection. Mean duration from operation to peritoneal recurrence was 17.0 ± 10.3 months. Of these patients with peritoneal recurrence, 29 patients (34%) had recurrence in =1 other organ. Multivariate analysis showed that age (=60 y: HR = 0.531; p = 0.0182), pathological T4 (HR = 3.802; p < 0.0001), lymph node involvement (HR = 3.491; p = 0.0002), and lymphadenectomy (D2: HR = 1.801; p = 0.0356) were independent predictors of peritoneal recurrence. The overall survival was lower in patients who developed peritoneal recurrence than in those with other recurrence (HR = 1.594; p = 0.002). LIMITATIONS: The regimens of adjuvant chemotherapy were limited to oral 5-fluorouracil. CONCLUSIONS: Our fndings clarifed the risk factors for peritoneal recurrence in patients who underwent curative resection for colon cancer.
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