Prevalence of RET/PTC1 and RET/PTC3 gene rearrangements in Chennai population and its correlation with clinical parameters.

Thyroid cancer is one of the most common endocrine disorders in the world. In India, about 42 million people suffer from various thyroid disorders. However, based on population-based cancer registry (PBCR) and Chennai cancer registry, thyroid cancer is emerging as a common cancer particularly in Chennai. Papillary thyroid carcinoma is considered as the most prevalent cancer constituting about 80-85 % of thyroid malignancies. Rearranged during transfection (RET)/papillary thyroid carcinoma (PTC) gene rearrangements are one of the major genetic alterations found in papillary thyroid carcinoma. This present study aims at estimating the frequency of RET/PTC1 and RET/PTC3 gene rearrangements in Chennai population and investigating the correlation between RET/PTC gene expressions with clinical parameters. Formalin-fixed paraffin-embedded (FFPE) tumor tissues obtained from 30 patients with papillary thyroid carcinoma were analyzed. Initially, to differentiate classic and follicular variants of papillary thyroid carcinoma samples, immunohistochemistry was performed. Thereafter, total RNA was isolated, and quantitative evaluation of RET/PTC1 and RET/PTC3 gene rearrangements by real-time PCR was performed. Chi-square test was performed to understand the correlation between positive and negative mutations of RET/PTC messenger RNA (mRNA) expression with clinical parameters. RET/PTC3 gene rearrangements were identified in 26/30 (86.67 %) cases, and none of the patient in our series had RET/PTC1 gene rearrangements. There was no statistically significant difference observed between positive and negative mutations of RET/PTC3 mRNA expression with clinic pathological parameters. Our results indicate that RET/PTC3 gene rearrangements are the most prevalent form of rearrangements in PTCs of Chennai population.