Conditional disease‐free survival rates and their associated determinants in patients with epithelial ovarian cancer: A 15‐year retrospective cohort study

BACKGROUND: The most common type of ovarian cancer (OC) is epithelial ovarian cancer (EOC) which is the most lethal gynecologic malignancy in adult women. AIM: This study aimed to determine the conditional disease‐free survival (CDFS) rates and their associated determinants in patients with EOC. METHODS AND RESULTS: The clinical and demographic data of 335 patients with confirmed EOC at Motahari Clinic (Shiraz, Iran) were retrospectively reviewed and analyzed. Traditional DFS (TDFS) and CDFS were calculated using the Kaplan–Meier method and cumulative DFS estimates, respectively. To evaluate the effects of the prognostic determinants on the DFS of the patients, a multiple covariate Cox analysis using the landmarking method was applied. The 1‐ and 3‐year TDFSs were 81.1% and 47.0%, respectively, and decreased over time. At baseline, a higher stage tumor and endometrioid histology were associated with a higher risk of recurrence when compared to stage I and other histological subtypes, respectively. The hazard of recurrence for older women (age ≥55 years) was approximately twice and three times more than that of women aged <45 years at 1‐ and 3‐year landmark time points, respectively. CONCLUSION: The age at diagnosis, defined by a cut‐off of 55 years, was a prognostic factor for the CDFS of EOC women. Moreover, patients with advanced‐stage EOC (ASEOC) (stages III and IV) and endometrioid histology had poorer CDFSs compared to those with early‐stage EOC (ESEOC) (stages I and II) and other histological types. In ESEOC patients with age at diagnosis of >55 years, CDFS gradually decreased in 3 years after remission which should be considered for follow‐up care decision‐making.