Joshua Melson, MD, Vice-chair, CGA-IGC Research Committee
The most common gynecologic cancer is endometrial cancer (EC). Clinical outcomes for Black women with EC tend to be worse than for White women. There may be multiple reasons for this observed outcome disparity. EC can occur in the setting of a defined germline pathogenic variant (gPV). Lynch syndrome (LS) is a common gPV associated with a tumor characteristic of high microsatellite instability, which tends to be more responsive to immune checkpoint inhibitors. In the current study, Dr. Liu and colleagues looked at gPV status across 76-90 cancer predisposition genes, including for LS status, across distinct patient ancestries using MSK-IMPACT tumor-normal targeted sequencing. The correlation of ancestry with gPVs was assessed both by patient self-reporting and by an alternative approach derived from MSK-IMPACT to assess genetic ancestry.
The authors found that among 1625 patients with EC, the rate of gPV was 13%. For self-reported ancestry gPV status in. Ashkenazi Jewish was 20%, Asian 12%, Black/African American (AA) 7.0%Hispanic, 12% and non-Hispanic (NH) White 14%.
Even after adjusting for covariates in regression models, Black/AA showed a lower rate of gPV, and Ashkenazi Jewish women showed a higher likelihood of a gPV. Black women had lower rates of microsatellite instability-high tumors in patients of Black/AA in comparison to Whites. The authors also looked at patient compliance follow-up when a gPV is identified and found that among those with newly identified gPVs the lowest rate of genetics follow-up occurred in Black patients.
In sum, this study showed that having a gPV and microsatellite high status is lower in Black patients compared to those of other ancestries. This type of phenotype may affect therapies and prevention for EC and that may be a contributing factor in the current racial disparities seen in EC outcomes across race.
This study was concurrently published online in Cancer on October 27th, 2023.