Germline alterations in cancer susceptibility genes in women with high-risk bladder cancer: Implications for germline testing and clinical management.

Abstract

418 Background: Gender differences exist in bladder cancer incidence, stage at diagnosis, and outcomes. Women have lower incidence of bladder cancer but are diagnosed with more advanced disease at presentation. They also have less favorable outcomes even after adjusting for tumor stage and treatment modality. The biologic mechanisms underlying gender disparities in bladder cancer remain unknown. Methods: We leveraged a prospective matched tumor-normal genomic profiling initiative to determine the prevalence and spectrum of pathogenic/likely pathogenic (P/LP) germline variants in women with bladder cancer. Germline DNA was tested for mutations in ≥77 cancer susceptibility genes using next-generation sequencing in 686 patients with bladder cancer. Mutation frequency and clinical characteristics were assessed by gender. Results: A total of 184 (27%) women and 502 (73%) men with bladder cancer underwent germline testing; median age of diagnosis was 66 ± 11.3 and 65 ± 11.3 years, respectively. Twenty-two women (12%) had bladder cancer diagnosis at age ≤ 50 years. Both groups had similar rate of tobacco exposure (57% vs 63%, p = 0.1), family history of bladder cancer (10% vs 10%, p = 0.5), and disease stage at diagnosis (non-muscle invasive bladder cancer [NMIBC] 54% vs 54%, MIBC 38% vs 39%, and metastatic disease 8% vs 6%, p = 0.7). Women had more non-urothelial carcinoma histology than men (adenocarcinoma 5% vs. 1%; squamous cell carcinoma 1% vs 0.2%, p = 0.001). More P/LP germline variants were found in women than men (38 [21%] vs. 70 [14%], p = 0.04). Twenty-eight women (15%) had P/LP variants in DNA-damage repair (DDR) genes; 23 (13%) carried moderate/high penetrance germline mutations, the most common were BRCA1/ 2, CHEK2, NBN, ATM, and MITF. Current clinical guideline for referral for genetic testing failed to identify 12 (52%) women with moderate/high penetrance germline mutations. Nine women (5%) carried germline mutations associated with increased risk of ovarian/endometrial cancers ( BRCA1/ 2 [5], ATM [2], MLH1 [1], TP53 [1]). Conclusions: Deleterious germline alterations are commonly present in women with high-risk bladder cancer. The presence of germline variants in some genes, such as BRCA1/2, can guide cancer screening and risk-reducing surgeries for patients and their families. Women with high-risk bladder cancer should be evaluated for suitability of germline testing, especially those who desire preservation of uterus and ovaries at the time of radical cystectomy, to rule out the presence of P/LP variants that increase risk of future gynecologic malignancies.