| ObjectiveRadiation therapy is a main way for patients with nasopharyngeal carcinoma ( NPC). Due to the different patients have different radi-osentivity, so probe the predictors of radiosensitivity in selecting an individual radiotherapy for patients with NPC have an important significance. This study was designed to evaluate the relationship between cyclin Dl and PCNA expression levels and radiosensitivity in patients with NPC.Methods1. Clinical data: Between Jan 2002 and Jan 2003, 65 patients with NPC treated with primary radiation therapy in Liaoning Province Tumor Hospital and first affiliate hospital of China medical university. 44 were male and 21 were female. The ages ranged from 15 to 75 years ( median 49 years). All patients had low differentiated squa-mous cell carcinoma. There were 4 cases of stage I , 19 cases of stage II , 34 cases of stage III and 8 cases of stage IV. The NPC were treated with 6 MV X - ray accelerator therapy, DT 70 - 74 Gy/35 -37f, 7 - 8 w. The neck lymph nodes areas were irradiation with 70 -76Gy/35 -38f, 7 -8 w, including 6-12 Mev photon irradiation, 20 -26Gy/10 - 13f in patients with neck lymph node metastases. Rou-tine CT scanning of NP were obtained on 2 to 3 months after radiotherapy. Response of primary tumor to radiotherapy was classified into CR, PR, MR, NC and PD, according to the criterion of therapeutic e-valuation in China. The CR regarded as radiosensitive tumor; PR and MR as lower radiosensitive tumor. 2. Immunohistochemistry (IHC ) ; biopsy specimens of all primary tumor before radiotherapy were studied by means of SP immunohistochemical staining. Cyclin Dl protein is localized to the nucleus and cytoplasm, and PCNA protein located the nucleus. Cyclin Dl and PCNA positive index: the percentage of positive cells relative to the total numbers of tumor cells examined. Cyclin Dl expression were divided into two groups: the intensity of the staining were moderate or strong and the number of the cells more than 5% defined as the positive expression; the rest were negative. The positive index ^25% was used as a cut - off for PCNA overexpres-sion. 3. Statistical analysis of the correlation between several factors and response of primary tumor to radiotherapy were performed.Results1.Cyclin Dl positive rate was 60% and PCNA overexpression rate was 52. 3% in 65 patients. Cyclin Dl positive rate and PCNA overexpression rate were 50% , 52. 6% , 64. 7% and 62. 5% , and 47.4% , 58. 5% , 50% and 25% , respectively, in stage I , II , 1 and IV. 2. Radiosensitive tumor were 40 cases (61.5% ) and low radiosensitive were 25 cases(38. 5% ). No NC and PD cases. 3. Uni-variate analysis showed that the CR were 100% , 78.9% , 55.9% and 25% , respectively, in stage I , II ,III and IV, (P<0.01). 29(74. 4% ) of 39 patients with cyclin Dl positive had CR, which was higherthan those of patients with cyclin Dl negative ( CR was 42.3%) ( P < 0.01). In each stage, CR of cyclin Dl positive were significantly higher than those of cyclin Dl negative. There were 28 (82.4% ) had CR in 34 cases with PCNA overexpression, which was higher than those of patients with low levels of PCNA( 38. 7% ) ( P < 0. 01). In each stage, CR of PCNA overexpression were significantly higher than those of low levels of PCNA. There were no significant different between response of tumor to radiotherapy and patients age, sex and tumor size. 4.Logistic multivariate regression analysis showed that significant influence response of tumor to radiotherapy were PCNA, clinical stage, tumor size, patients age and sex, in proper order.ConclusionNPC patients with PCNA overexpression or cyclinDl positive were more radiosensitive than those of patiants with low levels of PCNA or cyclinDl negative. As a predictor of radiosensitivity , PCNA may have more significant implication than cyclin Dl. These biological markers could serve as a useful predictor of making individual therapy for NPC patiens.
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