The OVHIPEC-1 trial previously showed that the addition of hyperthermic intraperitoneal chemotherapy (HIPEC) to interval cytoreductive surgery resulted in improved progression-free and overall survival compared with cytoreductive surgery alone at 4·7 years of follow-up in patients with stage III epithelial ovarian cancer who were ineligible for primary cytoreduction. We report the final survival outcomes after 10 years of follow-up.

In this open-label, randomised, controlled, phase 3 trial, patients with primary epithelial stage III ovarian cancer were recruited at eight HIPEC centres in the Netherlands and Belgium. Patients were eligible if they were aged 18–76 years, had not progressed during at least three cycles of neoadjuvant carboplatin plus paclitaxel, had a WHO performance status score of 0–2, normal blood counts, and adequate renal function. Patients were randomly assigned (1:1) to undergo interval cytoreductive surgery without HIPEC (surgery group) or with HIPEC (100 mg/m² cisplatin; surgery-plus-HIPEC group). Randomisation was done centrally by minimisation with a masked web-based allocation procedure at the time of surgery when residual disease smaller than 10 mm diameter was anticipated, and was stratified by institution, previous suboptimal cytoreductive surgery, and number of abdominal regions involved. The primary endpoint was progression-free survival and a secondary endpoint was overall survival, analysed in the intention-to-treat population (ie, all randomly assigned patients). This study is registered with ClinicalTrials.gov, NCT00426257, and is closed.

Between April 1, 2007, and April 30, 2016, 245 patients were enrolled and followed up for a median of 10·1 years (95% CI 8·4–12·9) in the surgery group (n=123) and 10·4 years (95% CI 9·5–13·3) in the surgery-plus-HIPEC group (n=122). Recurrence, progression, or death occurred in 114 (93%) patients in the surgery group (median progression-free survival 10·7 months [95% CI 9·6–12·0]) and 109 (89%) patients in the surgery-plus-HIPEC group (14·3 months [12·0–18·5]; hazard ratio [HR] 0·63 [95% CI 0·48–0·83], stratified log-rank p=0·0008). Death occurred in 108 (88%) patients in the surgery group (median overall survival 33·3 months [95% CI 29·0–39·1]) and 100 (82%) patients in the surgery-plus-HIPEC group (44·9 months [95% CI 38·6–55·1]; HR 0·70 [95% CI 0·53–0·92], stratified log-rank p=0·011).

These updated survival results confirm the long-term survival benefit of HIPEC in patients with primary stage III epithelial ovarian cancer undergoing interval cytoreductive surgery.

Dutch Cancer Foundation (KWF Kankerbestrijding).