Specialized care and survival of ovarian cancer patients in The Netherlands: Nationwide cohort study
Background: There is much debate on the necessity of regionalization of ovarian cancer care. We investigated the association between hospital type and survival of patients with ovarian cancer in The Netherlands. Methods: A retrospective, population-based cohort study was performed on all Dutch patients diagnosed with ovarian cancer from January 1, 1996, through December 31, 2003. We used data from the Netherlands Cancer Registry that were linked to mortality data from the Statistics Netherlands database to obtain the date and cause of death. Five-year relative survival ratios, defined as the ratio of the observed survival in the patient population to the expected survival of women in the general population with the same age, were determined for the total population and for groups stratified by tumor stage and/or hospital type. The association between hospital type and disease-specific survival was analyzed by use of multivariable Cox regression analyses. Results: We analyzed data from 8621 women with epithelial ovarian cancer, of whom 3482 (40%) were treated in general hospitals, 3510 (41%) were treated in semispecialized hospitals, and 1557 (18%) were treated in specialized hospitals. Five-year relative overall survival ratios of patients treated in general, semispecialized, and specialized hospitals were 38.0% (95% confidence interval [CI] = 36.0% to 39.9%), 39.4% (95% CI = 37.5% to 41.4%), and 40.3% (95% CI = 37.4% to 43.1%), respectively; median survival of patients aged 50-75 years was 36 months (interquartile range [IQR] = 13 to >54 months), 37 months (IQR = 14 to >54 months), and 38 months (IQR = 15 to >55 months), respectively. Age and cancer stage were associated with the relationship between hospital type and ovarian cancer-specific survival but histologic tumor type, grade, year of diagnosis, and socioeconomic status were not. Among patients with early-stage ovarian cancer, treatment in semispecialized and specialized hospitals was associated with lower risks of ovarian cancer-specific mortality than treatment in general hospitals. Among patients with stage I-IIA disease who were aged 50-75 years, risk of ovarian cancer-specific mortality was 30% and 42% lower after treatment in semispecialized and specialized hospitals, respectively, than in general hospitals (for semispecialized hospitals, hazard ratio [HR] = 0.70, 95% CI = 0.53 to 0.93; for specialized hospitals, HR = 0.58, 95% CI = 0.38 to 0.87). Among patients with advanced ovarian cancer, hospital type was not associated with survival. Conclusion: Hospital type was statistically significantly associated with survival among Dutch ovarian cancer patients with early-stage ovarian cancer: Patients who were treated in specialized and semispecialized hospitals survived longer than patients treated in general hospitals.