Real-world demographics and survival outcomes of patients in England with advanced or recurrent endometrial cancer by mismatch repair status

Real-world data on the impact of mismatch repair (MMR) status in patients with advanced/recurrent endometrial cancer (A/R EC) are limited. England's National Disease Registration Service data were used to characterize outcomes by MMR status in patients with A/R EC potentially eligible for frontline immune-checkpoint inhibitor (ICI) treatment in addition to chemotherapy.

Patients in this noninterventional, retrospective study were diagnosed with A/R EC between 2019 and 2021; received frontline chemotherapy; and met inclusion/exclusion criteria for the phase 3 RUBY trial (NCT03981796). Demographics, disease characteristics, and treatment patterns were reported. Overall survival (OS) and time-to-next-treatment (TTNT) were evaluated from initiation of frontline chemotherapy using Kaplan–Meier methodology.

Among 1452 ICI-eligible patients, 711 had MMR test results. Of these, 158 patients had MMR deficient (dMMR) tumors, and 547 had MMR proficient (MMRp) tumors. The dMMR cohort was younger (median, 64.4 years) with a larger percentage of endometrioid tumors (79.7%) than the MMRp (68.2 years and 40.8%, respectively) and untested cohorts (68.6 years and 41.2%, respectively). Median OS and TTNT were not reached in the dMMR cohort (median follow-up, 25.4 months); 34.6 (95% CI, 28.9–42.6) and 18.2 (95% CI, 15.3–22.1) months, respectively, in the MMRp cohort (median follow-up, 23.4 months); and 37.2 (95% CI, 27.4–45.9) and 18.2 (95% CI, 15.4–22.7) months, respectively, in the untested cohort (median follow-up, 24.3 months).

In this real-world study, 51% of patients lacked MMR test results, reflecting the need for improved testing awareness. Among those tested, overall outcomes support the need for more effective frontline regimens to treat A/R EC.