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

Abstract

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.