Loss of p27(KIP1) expression predicts poor prognosis in patients with esophageal squamous cell carcinoma

Immunohistochemical studies of cell cycle-regulating proteins were conducted on tissue samples from 106 patients with esophageal squamous cell carcinoma. Reduction of p27(KIP1) was observed in 41 (39%) cases and was significantly associated with a poor prognosis by univariate and multivariate analyses (p = 0.015). In contrast, p16(INK4) expression was reduced in 55 (52%) of the cases and was not correlated with prognosis. p27(KIP1) was not correlated with the PCNA index, while p16(INK4) expression was inversely correlated with the PCNA index (p = 0.01). The expression of these two proteins was not correlated with the clinicopathological parameters of the patients. Nodal status was shown by univariate analysis (p = 0.01) to be a prognostic factor, and poorly differentiated tumors were significantly associated with a poor prognosis by multivariate analysis (p = 0.027). Thus, reduction of p27(KIP1) plays an important role in the progression of esophageal squamous cell carcinomas and is considered to be an independent prognostic indicator of this disease.