Cigarette smoking is a known risk factor for bladder cancer. Smokers have been reported to have greater ERCC2-Signature mutations and APOBEC-Signature 13 mutations when compared to non-smokers in a TCGA based study (PMID: 33849962). Our objective was to assess the frequency of targetable genomic alterations in smokers (current or past) vs never smokers patients (pts) with locally advanced or metastatic urothelial carcinoma (mUC).
In this IRB approved retrospective study, smokers vs non-smokers pts with mUC undergoing tumor comprehensive genomic profiling (CGP) from CLIA-certified laboratory were included. Genes with alterations (GA) in < 5% pts and variants of unknown significance were excluded from the analysis. A chi square test was used to compare gene frequency aberration and the analysis was adjusted for false discovery using Benjamini-Hochberg (BH) correction. The median number of genomic aberrations per pt was compared using Wilcoxon rank-sum test.
137 pts were eligible and included. Smokers (n=70) and non-smokers (n=67): median age, 67 vs 68 years; male vs female: 55/15 vs 42/25. The genomic aberrations enriched in smokers and non-smokers are shown in the table. The most common GA observed in smokers were TERT, TP53, CDKN2B, RB1 and KDM6A; and non-smokers were TERT, TP53, CDKN2B, PIK3CA and RB1 (Table). Tumor mutation burden and the frequency of genomic aberrations per pt were similar in both groups.
Herein, we independently validate the findings by Walasek, Almassi et. al. (abstract B20, AACR 2020) of no significant difference in the tumor GA between smokers vs non-smokers pts with advanced urothelial carcinoma, despite high prevalence of targetable genomic aberrations in both cohorts. Future directions should include the investigation of epigenomic changes and transcriptomic profiling to further elucidate the effect of smoking on bladder cancer.