Background: The evolution of diagnostic procedures has resulted in an increase in early detection of pathologically T1 (pT1) colorectal cancer (CRC). However, the risk factors affecting long-term outcomes of patients with pT1 CRCs have been unclear. The aim of the present study was to identify risk factors for postoperative recurrence and overall survival in patients with pT1 CRC. Methods: Between January 1990 and January 2003, a total of 284 patients with pT1 CRC underwent radical surgery in the authors' institution. The impact of clinicopathological factors on postoperative recurrence and overall survival was estimated by univariate and multivariate analysis. Results: The median follow-up period was 55 months (interquartile range: 47.1 months). Postoperative recurrence occurred in 8 (2.8%) patients. The overall 5-year and 10-year disease-free survival rates were 98.4 and 92.7%. Multivariate analysis showed the presence of lymphatic invasion only was an independent risk factor for postoperative recurrence in pT1 CRC patients (hazard ratio: 11.622; P = 0.003). The 5-year and 10-year disease-free survival rates of the patients in N-ly- group, the N-ly + group, and the N+ group were 99.5%/98.2% and 96.3%/75.2%, and 93.3%/93.3%, respectively. Additionally, 4 of the 8 recurrences were found more than 5 years after the operation. Conclusions: Lymphatic invasion was an independent risk factor for recurrence in pT1 CRC patients.
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