Tissue P16 is Associated with Smoking Status among Indonesian Nasopharyngeal Carcinoma Subjects

BACKGROUND: Nasopharyngeal carcinoma (NPC) is a malignancy with high incidence in Southern China and South-East Asia. NPC incidence among males in Indonesia is estimated around 8.3/100,000 populations. Tobacco smoking is a common risk factor for cancer, including NPC. P16 is one of the key proteins related to the activation of apoptotic pathways, that commonly change during carcinogenesis. Carcinogenesis is often related to environmental exposure, including tobacco smoke. OBJECTIVE: To analyze the association between P16 protein and smoking status among NPC subjects in Indonesia. METHODS: Forty formalin fixed-paraffin embedded NPC tissue samples of known smoking status (20 smokers, 20 non-smokers) were collected from the Department of Anatomical Pathology, Dr. Sardjito Hospital, Yogyakarta. P16 was detected by immunohistochemistry staining. German semi-quantitative scoring system was applied to the P16 staining. Expression index with the score of 0 to 3 was classified as negative staining, meanwhile 4 to 12 was classified as positive staining. The association between P16 (score) and smoking status among NPC patients was analyzed using Fischer exact test. One-sided p ≤ 0.05 was considered as statistically significant. RESULTS: All samples were Javanese males, with age range 25-76 years old. P16 positive staining among smokers was 5% (1/20), while among non-smokers was 40% (8/20). P16 among smokers was significantly lower than non-smokers patients (p=0.010). No difference was found between quantity of smoke and P16 score. CONCLUSION : A significant association between P16 and smoking status in Indonesian NPC patients has been revealed. The result of this study may be used to improve prevention and management of NPC cases related to smoking habit in Indonesia.