A prospective study of p53 expression and its correlation with clinical response of radiotherapy in nasopharyngeal carcinoma

Objectives/Hypothesis: Nasopharyngeal carcinoma (NPC) is a common malignant neoplasm of the head and neck that occurs in people in the southeastern As ian area, including Taiwan, The significant association of p53 expression i n NPC suggested that p53 overexpression seemed to occur at an early stage i n the development of NPC. Alterations of p53 status were probably the most commonly encountered in head and neck carcinomas, and there was extensive e vidence that p53 status might determine tumor response to therapy. Ionizing radiation was studied extensively for the relationship between its damagin g effect and p53 status in human cancer cells. Study Design: This study was carried out to investigate whether there was any correlation between overe xpression of p53 protein and locoregional tumor response in patients with N PC treated with 7000 cGy of radiotherapy. Methods: Sixty-eight patients (50 males, 18 females) with NPC who were diagnosed and treated with radiothera py were studied prospectively, Before they had received a radiation dose of 7000 cGy in 35 fractions, five fractions a week, p53 status from a nasopha ryngeal biopsy was studied using immunohistochemical staining (MC). Results : The locoregional response rate of primary tumor was analyzed statisticall y. Forty-seven patients (69.1%) showed positive p53 staining in their tumor s. There were 5 positive stains in 6 squamous cell carcinomas (SCC; 83.3%), 34 positive in 53 non-keratinizing carcinomas (NKC; 64.2%), and 8 positive in 9 undifferentiated carcinomas (UC; 88.9%). The mean ages for patients w ith three different histopathologies were 48.5, 46.1, and 61.1 years. There were 8 patients (7 positive stains, 1 negative stain) with residual tumor after radiotherapy and all were NKC (6 males, 2 females). Therefore, the cl inical response rate of primary tumor was 85.1% in positive p53 immunostain ing (40 of 47 cases), 95.2% in those with no immunostaining (20 of 21 cases ); the former was poorer in locoregional tumor response than the latter, bu t there was no significant difference (P > .05, chi (2) test). Conclusions: We conclude that there is no statistically significant correlation in loco regional response of primary tumor between p53 overexpression and radiother apy in patients with NPC (P > .05, Fisher exact test).