Delayed interval debulking (6-cycle NAC) shows no DFS gain vs standard 3-cycle timing in CHRONO ovarian cancer

CHRONO (NCT03579394) tested whether delaying complete cytoreductive surgery after neoadjuvant platinum-taxane chemotherapy improves outcomes in FIGO stage IIIB–IVA high-grade epithelial ovarian cancer that was deemed amenable to complete surgery after 3 NAC cycles: standard interval debulking after 3 cycles plus adjuvant chemo (control; n=103) vs 3 additional NAC cycles then surgery plus fewer post-op cycles (experimental; n=106), with maintenance per local SOC. With 40.4 months’ median follow-up, median DFS was 20.2 vs 23.4 months (HR 0.88, p=0.48) and CC0 (complete macroscopic resection) rates were high in both arms (83.2% vs 90%); major 30-day post-op complications numerically increased with delay (5% vs 11%; p=0.11) with no 30-day deaths and no meaningful QoL differences. In context, the long-standing SOC for patients not suitable for complete primary debulking is 3-cycle NAC → interval debulking → chemo (supported by EORTC 55971/CHORUS showing non-inferior survival vs primary debulking), and CHRONO suggests that extending NAC to 6 cycles in “chemosensitive, resectable-at-3-cycles” patients does not clearly improve DFS over that benchmark.