Racial and Sex Differences in Tumor Genomics in Urothelial Carcinoma

Various studies have demonstrated significant differences in bladder cancer mortality across sex and race. These are partly related to differences in social and environmental factors, in addition to varying degrees of access to healthcare. Unfortunately, patients from diverse ancestries are often underrepresented in genomic cohorts. Nyame et al. investigated the hypothesis that tumor mutational burden (TMB) and other tumor features vary according to patients’ sex and race.

The researchers collected tumor mutation data from cBioPortal for 796 patients across six studies. The average age in the cohort was 67 years, 76% of patients were male, 81% had invasive disease, and 53% were White. Importantly, data on race were absent for 38% of patients. The median total mutation count did not differ significantly between females (92; IQR: 13, 191) and males (91; IQR: 21, 204; p = 0.62). Similarly, there were no significant differences in the proportion of actionable mutations between males and females (p = 0.86). While mutations in DNA damage repair genes were slightly less common among females (41%) relative to males (48%), this difference was also non-significant (p = 0.13). After adjusting for age and invasiveness, males exhibited increased risk of mutations in ARID1A, CHD6, and NCOR1.

There was no significant difference (p = 0.64) in the total mutation count between White patients (median: 129; IQR: 46, 261) and non-White patients (median: 91; IQR: 43, 198). Similarly, there was no significant difference in the frequency of actionable mutations (p > 0.99). There was a trend towards a lower frequency of mutations in DNA damage repair genes among non-White patients (39%) compared with White patients (51%), but this did not reach significance (p = 0.08). After adjusting for age and invasive status, White patients exhibited a higher risk of mutations in ARID1A, EP300, PIK3CA, and TP53 and a lower risk of mutation in HRAS than non-White patients.

The underrepresentation of patients with urothelial cancer from diverse ancestries is a major barrier to understanding the biological and socioeconomic variables that lead to healthcare disparities.

These limitations highlight the need for enrolling more diverse populations in genomic studies with detailed and standardized documentation of these variables to allow for in-depth analyses.

Written by: Bishoy M. Faltas, MD, Director of Bladder Cancer Research, Englander Institute for Precision Medicine, Weill Cornell Medicine

Reference:

Nyame YA, Baker KK, Montgomery B, Grivas P, Redman MW, Wright JL. Racial and sex differences in tumor genomics in urothelial carcinoma [published online ahead of print, 2023 Jul 20]. Urol Oncol. 2023;S1078-1439(23)00234-X.

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