Bcl-2 and proliferating cell nuclear antigen (PCNA) expression correlates with subsequent local recurrence in nasopharyngeal carcinomas.

Abstract

Many anticancer treatments, including radiation therapy, have been demonstrated to work through apoptosis. The treatment of choice on nasopharyngeal carcinoma (NPC), a radiosensitive tumor, is radiotherapy. Apoptosis therefore provides a good model to predict or re-evaluate the therapeutic response in NPC. Cellular genes such as p53 and bcl-2 have been shown to be involved in apoptosis. Proliferating cell nuclear antigen (PCNA) is a useful marker for proliferating cells. This study was designed to investigate whether the expression of p53, bcl-2 and PCNA, evaluated on tumor specimens obtained at diagnosis, is indicative of the subsequent local recurrence and distant metastasis following radiation therapy. We analyzed the expression of p53, bcl-2 and PCNA by immunohistochemical methods from NPC specimens prior to radiation therapy. A total of 63 T3/T4 NPC patients including 10 patients with local relapse (Group I), 19 patients with distant metastasis (Group II), and 34 disease-free patients (Group III) were assessed. Six of the 10 (60%) group I NPC, 4 of the 19 (21.1%) group II NPC, and 13 of the 34 (38.2%) group III NPC exhibited positive p53 expression. For bcl-2 immunostaining, 8 of the 10 (80%) group I NPC, 10 of the 19 (52.6%) group II NPC, and 10 of the 34 (29.4%) group III NPC were positive. High PCNA labelling index was shown in 6 of the 10 (60%) group I NPC, 7 of the 19 (36.8%) group II NPC, and 5 of the 34 (14.7%) group III NPC. The bcl-2 and PCNA reactivity in NPC developing local recurrence after radiation therapy was significantly higher than that in the disease-free NPC (p < 0.05). These findings show that the overexpression of bcl-2 and high PCNA labelling index are probably related to local relapse in NPC patients receiving radiation therapy alone as primary treatment.