Comparative effectiveness of upfront treatment strategies in elderly women with ovarian cancer

Background: Observational studies comparing neoadjuvant chemotherapy to primary surgery for advanced-stage ovarian cancer are limited by strong selection bias. Multiple methods were used to control for confounding and selection bias to estimate the effect of primary treatment on survival for ovarian cancer.

Methods: The Surveillance, Epidemiology, and End Results (SEER)-Medicare database was used to identify women ≥ 65 years of age with stage II-IV epithelial ovarian cancer who survived > 6 months from the date of diagnosis and received treatment from 1991 through 2007. Traditional regression analysis, propensity score-based analysis, and an instrumental variable analysis (IVA) using geographic location as an instrument were used to compare survival between neoadjuvant chemotherapy and primary surgery.

Results: A total of 9587 patients with stage II-IV ovarian cancer were identified. Use of primary surgery decreased from 63.2% in 1991 to 49.5% by 2007, whereas primary chemotherapy increased from 19.7% in 1991 to 31.8% in 2007 (P < .0001). In the observational cohort survival (hazard ratio [HR] = 1.27; 95% confidence interval [CI] = 1.19-1.35) was inferior for patients treated with neoadjuvant chemotherapy; both median survival (15.8 versus 28.8 months) and 2-year survival (36% versus 56%) were lower in the neoadjuvant chemotherapy group compared to those who underwent surgery. In the IVA, primary treatment had minimal effect on overall survival (HR = 1.04; 95% CI = 0.67-1.60). The median survival for patients with a value of the instrument less than the median (24.0 months, 95% CI = 23.0-25.0) and greater than or equal to median value of the IV (24.0 months, 95% CI = 23.0-26.0) were similar.

Conclusions: Use of neoadjuvant therapy has increased over time. Survival with neoadjuvant chemotherapy did not differ significantly from primary surgery in elderly women in the United States.