Molecular investigation of FGFR3 gene mutation and its correlation with clinicopathological findings in Indian bladder cancer patients

Background: Molecular alteration of FGFR3 gene is the most common genetic event currently known in bladder cancer. Notably, FGFR3 mutation has emerged as a promising molecular biomarker for recurrence, prognosis, and therapeutic target in bladder cancer. Aim: The present study explored the frequency and distribution pattern of FGFR3 mutation in 100 Indian bladder cancer patients. Methods and results: Exons 7, 10, and 15 were subjected to nested PCR followed by bidirectional sequencing of the PCR products. Overall, FGFR3 gene mutations were identified in 19 bladder cancer patients (19%, 19 of 100). Most of the mutations were noted in exon 7 (15%), followed by exon 10 (4%). All mutations detected were missense in nature affecting amino acids at codons 248, 249, and 373. The S249C mutations were the most recurrent mutation seen in exon 7, while Y373C was commonly observed in exon 10. In contrast to exons 7 and 10, no mutations were seen in exon 15 in this study. Females and older age patients tend to show increased frequency of FGFR3 mutations. Furthermore, FGFR3 mutations were more common in low pathological stage (6/20 pTa and 13/71 pT1) and low-grade tumors (13/46). This predominance in low-grade tumors were significantly high in comparison to high-grade tumor (P = .04). Likewise, FGFR3 mutations were significantly higher in well-differentiated tumors (32.6%, 14/43) in comparison to moderately differentiated tumors (11.3%, 5/44), and poorly differentiated tumor (0%, 0/13) (P = .007). No other association of FGFR3 with tumor size, necrosis, and variant histology was noted. Conclusions: The current study highlights the spectrum of FGFR3 mutation in Indian patients, and the data presented here are similar to those reported from across the globe.