Genetic Polymorphism Of Glutathione S-Transferase P1 (GSTP1) Gene and Its association with Bladder Cancer Susceptibility

INTRODUCTION: Bladder cancer is one of the most common urological malignancies. As per the Indian cancer registry data, it is the ninth most common cancer in men accounting for 3.9% of all cancer cases. In the middle-aged and elderly men; bladder cancer is the second most prevalent malignancy after prostate cancer. It is well documented that the tobacco smoke and occupational carcinogens promote epithelial cell dysplasia and they are the most common environmental cause of urothelial carcinoma of the bladder. Most of these carcinogens are detoxified by phase II metabolic enzymes like Glutathione S transferase. It is hypothesized that polymorphisms in genes encoding these enzymes, affects susceptibility to develop urothelial cancers (UC). One of the extensively studied genes in this group is glutathione S-transferase P1 [GSTP1]. Studies of the relationship of polymorphisms of GSTP1 and UC of bladder have been equivocal, with some studies claiming positive associations with GSTP1 polymorphism while the others claiming a negative association. This present study aims to assess the association between genetic polymorphism of GSTP1 gene and development of UC of bladder in patients presenting to Christian Medical College and Hospital, Vellore. AIM / OBJECTIVES: This study aims to assess the association between genetic polymorphism of GSTP1 gene and development of UC of bladder in patients presenting to our hospital. MATERIAL AND METHODS: Prospective case control study from July 2012 - July 2013. We included cases with histological proven diagnosis of TCC bladder and excluded patients with cancer metastasized to bladder from any other origin, prior history of radiotherapy or chemotherapy. Controls individuals were patients with non-malignant urological diseases and a normal cystoscopy. Sample size of 45 in each group was calculated using power of 80%, expected frequency of risk allele in the control population of 0.28 and genetic effect for odds ratio 2.5. The genetic polymorphism of GSTP1 gene was compared in both the groups using SPSS 18. RESULTS: Most patients with UC of bladder were smokers. There was no significant association with the GSTP1 polymorphism and UC of bladder. No association was found even after a subset analysis was performed by stratifying population data into various geographical regions. CONCLUSIONS: Although lack of association between GSTP1313 G/G polymorphism and UC of bladder was seen in our study, it might be due to a small sample size or the effect of complex interaction between polymorphisms of other glutathione enzymes. It is also possible that the polymorphism is not associated with UC of bladder in our population. For further confirmation, large scale population-based studies are required