Secondary Cytoreduction Followed by Chemotherapy May Improve PFS in Ovarian Cancer

The phase 3 SOC-1 trial found an association between secondary cytoreduction followed by chemotherapy and prolonged progression-free survival when compared with chemotherapy alone for patients with relapsed ovarian cancer.

For patients with platinum-sensitive relapsed ovarian cancer, research found that secondary cytoreduction followed by chemotherapy was associated with statistically significant longer progression-free survival (PFS) rates when compared to chemotherapy alone, according to data published in Lancet Oncology.

With these findings in mind, this cohort of patients should be counseled about the option of secondary cytoreduction as the standard of care at specialized centers, according to the research team.

“Secondary cytoreduction followed by chemotherapy improved progression-free survival with acceptable morbidity compared with chemotherapy alone for patients with platinum-sensitive, relapsed ovarian cancer selected using (international model) scores and PET-CT imaging,” wrote the investigators. “All patients should be counselled about the options of secondary cytoreduction in specialised centres with high volumes of ovarian cancer surgery.”

The multicenter, open-label, phase 3 SOC-1 trial (NCT01611766) enrolled 357 patients with platinum-sensitive relapsed ovarian cancer. The cohort was randomized, with 182 patients assigned to undergo secondary cytoreductive surgery followed by intravenous chemotherapy 175 patients assigned to chemotherapy alone. Median follow-up was 36 months.

Median PFS for patients in the surgery group was 17.4 months (95% CI, 15.0-19.8) compared with 11.9 months (95% CI, 10.0-13.8) for patients in the no surgery group (HR, 0.58; 95% CI, 0.45-0.74; p < .0001).

Median overall survival at the interim analysis was 58.1 months (95% CI, not estimable-not estimable) and 53.9 months (95% CI, 42.2-65.5) for patients in the surgery group and no surgery group, respectively (HR, 0.82; 95% CI, 0.57-1.19).

The safety profile featured 5% of patients in the surgery group experiencing grade 3-4 surgical morbidity at 30 days, with 0 patients in either group at 60 days after receiving their respective treatment.

Common grade 3-4 adverse events (AEs) during chemotherapy included neutropenia (17% of patients in the surgery group vs 12% of patients in the no surgery group), leucopenia (8% of patients vs 5% of patients), and anemia (6% of patients vs 6% of patients). A total of 4 serious AEs occurred in the surgery group, with no treatment-related deaths observed in the total patient population.

“Although data for overall survival is immature, the prespecified interim analysis of overall survival showed no difference between the surgery group and the no surgery group,” wrote the investigators. “Times to first and second subsequent anticancer therapy, which are key endpoints between progression-free survival and overall survival, were also longer in patients in the secondary cytoreduction plus chemotherapy group than in those in the chemotherapy alone.”

The major limitation of the data according to the research team is the 37% of patients who crossed over from the no surgery group to the surgery group at subsequent relapses. These relapses have the potential to extend the median overall survival data in the no surgery group, leading to a reduction in the statistical ability to detect a negative result.

Moving forward, the research team explains that longer-term survival outcomes need to be assessed with mature overall survival and treatment-free survival data.

“The results of this trial support the efficacy of secondary cytoreduction in patients with relapsed ovarian cancer selected using iMODEL scores and PET-CT imaging,” wrote the investigators.

Reference:

Shi T, Zhu J, Feng Y, et al. Secondary cytoreduction followed by chemotherapy versus chemotherapy alone in platinum-sensitive relapsed ovarian cancer (SOC-1): a multicentre, open-label, randomised, phase 3 trial. Lancet Oncol 2021. https://doi.org/10.1016/ S1470-2045(21)00006-1