Proliferating Cell Nuclear Antigen as a Prognostic Factor After Total Mesorectal Excision of Stage II-III Rectal Cancer

Proliferating cell nuclear antigen (PCNA) is an auxiliary protein of DNA polymerase delta that is tightly associated with sites of DNA replication; whether PCNA is a definite prognostic factor remains controversial. This study determined the clinicopathological factors associated with the long-term oncological outcome after radical resection of stage II-III rectal cancer, focusing on PCNA. We retrospectively reviewed 135 consecutive patients who underwent curative surgery for stage II-III rectal cancer between August 2001 and April 2004. Prognostic factors including immunohistochemical PCNA expression and the clinical outcome were evaluated. The PCNA index correlated with lymph node metastasis (P = 0.010). A multivariate analysis identified two independent factors that significantly affected both disease-free and overall survival: lymph node metastasis and PCNA index. With a median follow-up period of 60 months (range 8-87 months), both 5-year disease-free and overall survival of the low PCNA group were significantly higher than those of the high PCNA group (71.8% versus 32.0%, P < 0.001; 83.9% versus 50.0%, P < 0.001, respectively). For patients undergoing curative resection for rectal cancer, pathological N stage and high PCNA expression can provide valuable prognostic information about survival. This study suggests that the PCNA index may be used as an independent prognostic factor in stage II-III rectal cancer patients.