376MO - The impact of crossover to surgery in the no-surgery group on the survival: A post-hoc analysis of the SOC-1 trial

Background

In the SOC-1 trial (NCT01611766), secondary cytoreduction significantly improved progression-free survival (PFS) in patients with platinum-sensitive relapsed ovarian cancer (PSROC). The predefined threshold for statistical significance was not met for overall survival (OS), which might be due to a high rate of patients in the no-surgery group (control group) crossing over to surgery following subsequent relapse. The impact of crossover on survival remains to be explored.

Methods

We conducted a post-hoc analysis of SOC-1 data to determine the impact of crossover to surgery following first subsequent relapse (during the third-line treatment) in the control group. The PFS and OS were estimated by Kaplan-Meier method.

Results

Of the 175 patients assigned to the control group in the SOC-1 trial, 149 (85%) patients had first subsequent relapse. Among the 149 patients, 55 (37%) patients had crossover and underwent cytoreductive surgery during the third-line treatment. The remaining 94 (63%) patients received systemic therapy only during the third-line treatment. Median PFS was 15.8 months for the patients treated with cytoreductive surgery and 10.2 months for those without surgery after first subsequent relapse (hazard ratio [HR] 0.48, 95% CI 0.33–0.70, P < 0.001). Median OS was 60.1 months for patients treated with cytoreductive surgery and 27.5 months for the patients without surgery (HR 0.46, 95% CI 0.30–0.71, P < 0.001).

Conclusions

In this analysis, a significantly improved PFS and OS were observed for patients who crossed over to surgery after the first subsequent relapse in the control group. For PSROC patients, surgical approach may still present a beneficial treatment option in the later-line treatment.

Clinical trial identification

NCT01611766.

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Zhongshan Talent Fund (no. 016, to R.Z.), the National Natural Science Foundation of China (nos. 81972429 and 82273388, to R.Z.) and Shanghai Municipal Science and Technology Major Project (no. 22Y21900300, to R.Z.) for funding this trial.

Disclosure

All authors have declared no conflicts of interest.