In a Chinese phase III trial (SOC-1) reported in The Lancet Oncology, Shi et al found that secondary cytoreduction followed by chemotherapy significantly prolonged progression-free survival vs chemotherapy alone in patients with platinum-sensitive relapsed epithelial ovarian cancer. No significant overall survival benefit was observed on interim analysis.

Study Details

The open-label trial included 357 women from four centers with a platinum-free interval of at least 6 months after the end of first-line platinum-based chemotherapy who were considered to have potentially resectable disease. Patients were randomly assigned between July 2012 and June 2019 to undergo secondary cytoreductive surgery followed by chemotherapy (n = 182) or chemotherapy alone (n = 175). Chemotherapy consisted of six 3-weekly cycles of paclitaxel at 175 mg/m² or docetaxel at 75 mg/m² plus carboplatin area under the curve = 5 mg/mL/min.

The primary endpoints were progression-free survival and overall survival in the intention-to-treat population. The current report provides the final progression-free survival analysis and a prespecified interim analysis of overall survival.

Progression-Free Survival

Overall, 172 patients in the surgery group (95%) underwent secondary cytoreduction surgery and 158 in the no-surgery group (90%) received protocol treatment. In the no-surgery group, 11 patients had secondary cytoreduction during second-line therapy, and 48 (37%) of 130 with disease progression crossed over to surgery at a subsequent recurrence.

Median follow-up was 36.0 months (interquartile range [IQR] = 18.1–58.3 months). Median progression-free survival was 17.4 months (95% confidence interval [CI] = 15.0–19.8 months) in the surgery group vs 11.9 months (95% CI = 10.0–13.8 months) in the no-surgery group (hazard ratio [HR] = 0.58, 95% CI = 0.45–0.74, P < .0001); 2-year rates were 38% vs 22%.

On interim analysis (after 105 deaths were recorded), median overall survival was 58.1 months (95% CI = not estimable–not estimable) in the surgery group vs 53.9 months (95% CI = 42.2–65.5 months) in the no-surgery group (HR = 0.82, 95% CI = 0.57–1.19).

Median time to first subsequent anticancer therapy was 18.1 months vs 13.6 months (HR = 0.59, 95% CI = 0.46–0.76) and median time to second subsequent anticancer therapy was 33.5 months vs 28.1 months (HR = 0.69, 95% CI = 0.51–0.94).

Adverse Events

Grade 3 surgical morbidity (no grade 4 complications) occurred in nine patients (5%) in the surgery group at 30 days, with the most common being pleural effusion (three patients, 2%). No patients in either group died within 60 days after receiving assigned treatment. Grade 3 or 4 adverse events during chemotherapy occurred in 25% of the surgery group vs 20% of the no-surgery group, with the most common being neutropenia (17% vs 12%), leukopenia (8% vs 5%), and anemia (6% vs 6%). Serious adverse events occurred in four patients in the surgery group, consisting of neutropenia in three (2%) and increased blood creatinine in one (1%). No treatment-related deaths were observed.

The investigators concluded, “Secondary cytoreduction followed by chemotherapy was associated with significantly longer progression-free survival than…chemotherapy alone in patients with platinum-sensitive relapsed ovarian cancer, and patients should be counselled about the option of secondary cytoreduction in specialized centres. Long-term survival outcomes will be assessed using mature data on overall survival.”

Rongyu Zang, MD, of Zhongshan Hospital, Fudan University, Shanghai, is the corresponding author for The Lancet Oncology article.

Disclosure: The study was funded by the Zhongshan Development Program. For full disclosures of the study authors, visit thelancet.com.