BCL-2 AND PROLIFERATING CELL NUCLEAR ANTIGEN (PCNA) EXPRESSION CORRELATES WITH SUBSEQUENT LOCAL RECURRENCE IN NASOPHARYNGEAL CARCINOMAS

Many anticancer treatments including radiation therapy, have been demo nstrated to work through apoptosis. The treatment of choice on nasopha ryngeal carcinoma (NPC), a radiosensitive tumor, is radiotherapy. Apop tosis therefore provides a good model to predict or re-evaluate the th erapeutic response in NPC. Cellular genes such as p53 and bcl-2 have b een shown to be involved in apoptosis. Proliferating cell nuclear anti gen (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 radia tion therapy. We analyzed the expression of p53, bcl-2 and PCNA by imm unohistochemical methods from NPC specimens prior to radiation therapy . A total of 63 T3/T4 NPC patients including 10 patients with local re lapse (Group I), 19 patients with distant metastasis (Group II), and 3 4 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 immunos taining, 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 l abelling 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 radiati on therapy was significantly higher than that in the disease-free NPC (p<0.05). These findings show that the overexpression of bcl-2 and hig h PCNA labelling index are probably related to local relapse in NPC pa tients receiving radiation therapy alone as primary treatment.