Hyperthermic Intraperitoneal Chemotherapy in Platinum-Sensitive Recurrent Ovarian Cancer: A Randomized Trial on Survival Evaluation (HORSE; MITO-18).

Purpose: To investigate whether the addition of hyperthermic intraperitoneal chemotherapy (HIPEC) to secondary cytoreductive surgery (SCS) without neoadjuvant chemotherapy has a benefit on progression-free survival (PFS), as opposed to SCS alone in patients with platinum-sensitive recurrent epithelial ovarian cancer (platinum-free interval, >6 months).

Methods: This was a multicenter randomized phase III study. Random assignment was performed at the time of surgery in cases with residual tumor ≤0.25 cm. HIPEC with cisplatin (CDDP) 75 mg/m² for 60 minutes at 41.5°C was administered at the end of surgery in the experimental arm. Both groups received postoperative platinum-based chemotherapy. The primary end point was PFS. The safety profile and postrecurrence survival (PRS) were the secondary end points.

Results: A total of 167 patients underwent random assignment, 82 patients to SCS plus HIPEC (experimental arm) and 85 to SCS alone (control arm). The median follow-up was 83 months (IQR, 64-102). The median PFS was 23 months (95% CI, 17 to 29) in the group that underwent surgery alone and 25 months (95% CI, 18 to 32) in the group that underwent cytoreductive surgery with HIPEC. The probability of PRS at 5 years was 61.6% (95% CI, 50.8 to 72.4) in the SCS group and 75.9% (95% CI, 66.5 to 85.3) in the SCS plus HIPEC group. The incidence of postoperative adverse events of any grade was similar between the two groups.

Conclusion: The addition of HIPEC to complete or nearly complete primary SCS did not confer a benefit in terms of PFS in patients with platinum-sensitive peritoneal recurrence.