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

Abstract

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