5589 Background: Heated Intraperitoneal Chemotherapy (HIPEC) at interval cytoreductive surgery (ICS) for high grade serous carcinoma of tubo-ovarian origin (HGSOC) improves overall survival (OS) by 11. 6 months and increases platinum sensitivity at recurrence. Our aim was to estimate the payer budget impact of adopting HIPEC in BRCA wild-type patients at a quaternary Canadian center. Methods: A retrospective review was conducted of patients undergoing surgery for metastatic HGSOC at Vancouver General Hospital, Vancouver, Canada between January 1 and December 31, 2024. A payer-perspective Markov model was constructed with monthly cycles and a five-year horizon. Six cycles of carboplatin and paclitaxel were costed in the initial episode. Health states were progression-free (PF), first platinum-sensitive recurrence (PS1), second platinum-sensitive recurrence (PS2), platinum-resistant recurrence (PR), and death. PF progression hazards were derived from median PFS reported in randomized clinical trials. Post-progression mortality hazards were calibrated to match OVHIPEC-1 median overall survival. Direct medical costs were estimated in 2025 Canadian dollars using publicly available provincial drug pricing data in British Columbia and institution-specific costs for surgery, HIPEC, and inpatient care. Results: Annual volume of ICS patients was 98, of whom 25 were eligible for HIPEC and wtBRCA. Over 5 years, with 25 new patients entering annually, total costs were 9. 05M without HIPEC versus 11. 07M with HIPEC, yielding an incremental budget impact of 2. 02M (16, 186 per patient). Incremental cost was driven by the surgical episode (+1. 90M), longer duration of maintenance niraparib (+0. 26M), and treatment of platinum-sensitive recurrence (+0. 15M) with carboplatin doublets. Incremental cost was partially offset by an estimated 11 fewer platinum-resistant recurrences within the 5-year horizon, resulting in cost savings of −0. 28M from reduced platinum-resistant treatment. Conclusions: Adding HIPEC at ICS to patients with stage III wtBRCA HGSOC increases 5-year payer spending by 2M for a 25 patient per year program. Additional cost is driven by provision of HIPEC surgery and postoperative care and is partially offset by near-term savings on platinum-resistant recurrence. Treatment cost across a 5-year horizon for 25 patients treated annually (n = 125). Category No HIPEC HIPEC Incremental Cost Incremental Cost Per Patient Surgery +/- HIPEC 2, 085, 500 3, 983, 250 1, 897, 750 15, 182 Initial chemotherapy 1, 829, 348 1, 829, 348 0. 00 0. 00 Niraparib Maintenance 2, 376, 117 2, 638, 599 262, 482 2, 100 Platinum Sensitive Recurrence 1, 243, 222 1, 389, 325 146, 103 1, 169 Platinum Resistant Recurrence 1, 515, 639 1, 232, 611 -283, 027 -2, 264 Total 9, 049, 824 11, 073, 132 2, 023, 308 16, 186
Milman et al. (Wed,) studied this question.