Association between hospital treatment volume and survival of women with gynecologic malignancy: Japan Society of Obstetrics and Gynecology study

Abstract

<h3>Objectives:</h3> To examine the effect of hospital treatment volume on overall survival outcomes with gynecologic malignancies in Japan. <h3>Methods:</h3> This society-based retrospective study in Japan included women with gynecologic malignancies who diagnosed from 2004-2015. The association between the annual hospital treatment volume (aHTV) and overall survival (OS) was examined per tumor type using a multivariable Cox proportional hazards model with restricted cubic splines. Institutions were categorized into 3 groups based on fractional proportions: High- (1-10 percentile), moderate- (11-50 percentile), and low- (51-100 percentile) volume centers. <h3>Results:</h3> A total of 206,845 women (Endometrial cancer n=80,741, cervical cancer n=73,647, and ovarian cancer n=52,457) at 431 hospitals were identified. There were 43 high-volume centers (34.6%, 40.5%, 31.5% of cases for endometrial, cervical, and ovarian cancer, respectively), 186 moderate-volume centers (50.3%, 49.8%, and 50.7% of cases), and 202 low-volume centers (15.1%, 9.8%, and 17.8% of cases) in the study sample. Among high-volume centers, the median annual hospital treatment volume were 52 (interquartile range (IQR), 44-71), 59 (IQR 50-80), and 34 (IQR 29-41) cases for endometrial, cervical, and ovarian cancer. Women treated at high-volume centers were younger, more likely to have rare tumor histology and to have undergone surgical management (<i>P</i><0.001). During the study period, the proportion of high-volume centers decreased, whereas that of low-volume centers increased significantly (<i>P</i><0.001) for all gynecologic tumors. Compared with low-volume centers, treatment at high-volume centers was associated with a reduction in overall mortality: adjusted-hazard ratio (aHR) 0.81, 95% confidence interval (CI) 0.76-0.87, aHR 0.77, 95% CI 0.73-0.83, and aHR 0.93, 95% CI 0.88-0.97 in endometrial, cervical, and ovarian cancer, respectively. Among initial surgical cases, the magnitude of statistical significance for overall survival was larger than that for the entire cohort across the three malignancies (aHR: 0.82; 0.86; and 0.89 for endometrial, cervical, and ovarian cancer). <h3>Conclusions:</h3> High-volume centers were associated with a higher likelihood of improved overall survival outcome in women with gynecologic malignancies in Japan. Centralization of cancer treatment may improve survival outcomes.