Impact of nonspecific death on overall survival in early-stage epithelial ovarian cancer patients.

ABSTRACT

OBJECTIVE: To estimate the impacts of nonovarian cancer-specific death (non-OCSD) and ovarian cancer-specific death (OCSD) on early-stage patients, and to determine which statistical method yielded survival results most similar to real-world situations. METHODS: Data of patients with early-stage epithelial ovarian cancer from 1988 to 2015 registered in the Surveillance, Epidemiology, and End Results database were analyzed. The primary outcome events of epithelial ovarian cancer were OCSD, non-OCSD, or alive. Incidences of non-OCSD and OCSD with different clinicopathological factors, cumulative incidences of non-OCSD and OCSD, and overall survival impact of non-OCSD were analyzed. RESULTS: A total of 1606 non-OCSD (8.9%) and 3022 OCSDs (16.8%) were analyzed. Several independent features were associated with non-OCSD, including age (>60 years), radiotherapy, and marital status. In patients with histology (eg, endometrioid or mucinous), well-differentiated cells, stage I disease, or widowed marital status, as well as age older than 60, non-OCSD rates of all causes of death notably distorted overall survival, resulting in inaccurate and biased interpretations. CONCLUSIONS: Overall survival was greatly influenced by non-OCSD in early epithelial ovarian cancer. Future clinical trials should consider non-OCSD as a competing risk event, especially among patients older than 60 years and those with well-differentiated cells, no chemotherapy, and widowed marital status.