Targeted deep sequencing of bladder tumors reveals novel associations between cancer gene mutations and mutational signatures with major risk factors.

Exome and whole-genome sequencing of muscle-invasive bladder cancer (BC) has revealed important insights into the molecular landscape; however, there are few studies of non-muscle invasive BC with detailed risk factor information.

We examined the relationship between smoking and other BC risk factors and somatic mutations and mutational signatures in bladder tumors. Targeted sequencing of frequently mutated genes in BC was conducted in 322 formalin-fixed paraffin-embedded bladder tumors from a population-based case-control study. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), evaluating mutations and risk factors. We used SignatureEstimation to extract four known single base substitution mutational signatures and Poisson regression to calculate risk ratios (RRs) and 95%CIs, evaluating signatures and risk factors. Results:Non-silent KDM6A mutations were more common in females than males (OR=1.83,95%CI:1.05-3.19). There was striking heterogeneity in the relationship between smoking status and established single base substitution signatures: current smoking status was associated with greater ERCC2-Signature mutations compared to former (p-value=0.024) and never smoking (RR=1.40, 95% CI: 1.09-1.80, p-value=0.008); former smoking was associated with greater APOBEC-Signature13 mutations (p-value=0.05); and never smoking was associated with greater APOBEC-Signature2 mutations (RR=1.54, 95% CI: 1.17-2.01, p-value=0.002). There was evidence that smoking duration (the component most strongly associated with BC risk) was associated with ERCC2-Signature mutations and APOBEC-Signature13 mutations among current (p-trend=0.005) and former smokers (p=0.0004), respectively.

These data quantify the contribution of BC risk factors to mutational burden and suggest different signature enrichments among never, former, and current smokers.

Clinical cancer research : an official journal of the American Association for Cancer Research. 2021 Apr 13 [Epub ahead of print]

Stella Koutros, Nina Rao, Lee Moore, Michael L Nickerson, Donghyuk Lee, Bin Zhu, Larissa Pardo, Dalsu Baris, Molly Schwenn, Alison Johnson, Kristine Jones, Montserrat Garcia-Closas, Ludmila Prokunina-Olsson, Debra T Silverman, Nathaniel Rothman, Michael Dean

Division of Cancer Epidemiology and Genetics, National Cancer Institute ., Division of Cancer Epidemiology and Genetics, National Cancer Institute., Laboratory of Translational Genomics, National Cancer Institute., Division of Cancer Epidemiology & Genetics, National Cancer Institute., Formerly of Maine Cancer Registry., Vermont Cancer Registry, Vermont Department of Health., Laboratory of Translational Genomics, Division of Cancer Epidemiology and Genetics, National Institutes of Health., LTG, NIH/NCI/DCEG.