Objectives We wished to assess the potential impact of directing EC management based on molecular classification, and the projected cost implications of molecular subtype-directed care.

Methods Surgical staging, treatment, surveillance, and hereditary cancer program(HCP) referrals were assessed for all ECs managed in a single calendar year (2016) across 24 Canadian centers. Variation of practice was recorded, as well as where a change in management would be projected and associated cost implications of that change based on molecular subtype assignment.

Results Data from 862 patients revealed wide variation in surgical staging, with lymph node dissection(LND) performed in 61% of ECs (range 25–100%), including 38% LND in Gr1ECs (0–100%). Adjuvant therapy (type, when/if given) and cancer surveillance (frequency, site e.g., community vs. cancer center) was inconsistent within and across centers for both early-and late-stage disease. Molecular classification identified 29% MMRd ECs (n=247) but only 8% of these women had been referred to HCP. 30 women who did consult HCP were MMRproficient. 38% of MMRd ECs had no LND and 43% did not receive radiation. 16% and 18% of p53abn ECs had no LND or omentectomy respectively, and only 58% received chemotherapy. De-escalation of treatment in early-stage POLEmut and NSMP ECs (n=63 treated, where molecular classification would direct observation or brachytherapy-only) would have reduced costs by $348,896–407,830CAD or $5538–6466CAD per patient.

Conclusions There is currently profound variation in practice for all aspects of EC management with implications to patients and health systems. Molecular classification can provide consistency in care and direct biologically-informed management.