Chemotherapy or upfront surgery for newly diagnosed advanced ovarian cancer: Results from the MRC CHORUS trial.

5500 Background: First line treatment of advanced ovarian cancer (OC) is accepted to be primary surgery (PS) followed by adjuvant platinum-based chemotherapy (P-CT). However, the EORTC55971 trial suggested neoadjuvant chemotherapy (NACT) is an alternative, showing increased optimal debulking rates and reduced surgical complications without detriment to survival. CHORUS (CRUK 07/009) is the 2nd phase III randomized controlled trial to investigate timing of initial surgery in OC. Methods: Patients (pts) with clinical FIGO stage III-IV OC (pelvic mass, extrapelvic metastases and CA125/CEA ratio >25) were randomized to standard treatment (PS followed by 6 cycles P-CT) or NACT (3 cycles P-CT either side of surgery). CHORUS was designed to demonstrate non-inferiority of NACT, excluding a 6% absolute detriment in 3yr survival from 50% expected with PS (1-sided alpha 10%). Primary outcome was overall survival (OS) and secondary outcomes were progression free survival (PFS), toxicity and quality of life. Results: ...