Racial differences in endometrial cancer molecular portraits in The Cancer Genome Atlas Racial differences in endometrial cancer molecular portraits in The Cancer Genome Atlas

Differences in patient demographic and tumour characteristics between patients of South Asian and White ethnicity diagnosed with an endometrial cancer (EC) and currently living in England are not well described. We undertook a retrospective study of EC cases diagnosed at the University Hospitals of Leicester, UK. A total of 1884 cases were included, with 13% of the patients being of South Asian ethnicity. South Asian women were diagnosed at a significantly younger age (mean age of 60.3 years) compared to women of White ethnicity (mean age of 66.9 years) with a mean difference of 6.6 years (95% CI 5.1 to 8.1, p < 0.001). Rising body mass index (BMI) in the White patient group was significantly correlated with younger age at diagnosis (p < 0.001); however, this association was not seen in South Asian patients. A linear regression that adjusted for diabetes status, BMI, and the interaction terms of diabetes status with BMI and ethnicity with BMI, highlighted a younger age of diagnosis in South Asian patients with a BMI less than 45 kg/m². The difference was greatest at lower BMIs for both non-diabetics and diabetics. Further investigation is needed to explain these differences and to determine their impact on suspected cancer referral criteria.

To identify differences in the mutational profile of endometrial tumours between British White (BW) and South Asian (BSA) women. We analysed primary tumours from matched cohorts of British White (BW) and British South Asian (BSA) women resident in Leicestershire diagnosed with EC. Next Generation Sequencing was performed to investigate mutational differences in a panel of 10 genes previously identified as being commonly mutated in EC. The presence of somatic Mismatch Repair (MMR) gene deficiencies was determined by immunohistochemistry. In total, 57 tumours (27 BSA and 30 BW) were sequenced. There was no significant difference in the overall mutation frequency of the 10 genes analysed; however, numerous differences were observed between the groups. There was a positive association between PIK3CA and PTEN mutations in the BSA group, with 78% of PIK3CA-mutant tumours harbouring a PTEN mutation, whereas only 11% of PIK3CA wild-type (wt) tumours were PTEN mutant positive (p = 0.0012). In BW women, 90% of ARID1A mutant tumours had co-existent PI3K pathway mutations versus 50% of wild-type (wt) ARID1A patients (p = 0.0485). This trend was not significant in the BSA group (p = 0.66). The age at diagnosis was significantly higher in the BW group with a somatic MMR gene deficiency compared to those with no deficiency (72.8 years versus 59.6 years, p = 0.007), whereas this difference was not seen in the BSA group (64 years versus 60 years, p = 0.37). We have identified differences in the mutational profile of primary EC tumours from BW and BSA women. Further research is needed to confirm these findings and to explore their potential implications for early detection, treatment response and prognosis.