Influence of hospital procedure volume on uterine cancer survival in Osaka, Japan.

Recent publications suggest that the relationships between hospital procedure volume and cancer survival may be different according to characteristics of the cancer such as primary site, extent of disease, and the year of diagnosis. The associations between hospital procedure volume and survival for uterine cancer, however, have never been studied in Japan. Data from the Osaka Cancer Registry were used to investigate this issue. Hospitals were ranked according to the number of operations for uterine cancer performed per year (high, medium, low, very low) in a diagnosis year period (1975-1981, 1982-1989 and 1990-1997). Survival analysis was carried out for the reported 7213 patients who lived in Osaka Prefecture (excluding Osaka City) diagnosed in 1975-1997, or patients who lived in Osaka City diagnosed in 1993-1997, because active follow-up data on vital status 5 years after diagnosis were available. The relative 5-year survival was higher with increased hospital procedure volume after 1982 (49.8, 68.6, 70.9, and 75.9%, respectively, in 1982-1989; 45.7, 62.7, 71.4, and 77.6%, respectively, in 1990-1997), and only survival in high-volume hospitals increased in the period 1975-1997. After adjustment for age, subsite, extent of disease and surgery by using the Cox regression model, patients receiving care in very low, low, or medium-volume hospitals were found to have a higher risk of death than patients receiving care in high-volume hospitals. Similar findings were obtained when the analysis was conducted separately for patients with cancer of the cervix and those with cancer of the corpus uteri. Although some limitations exist in this study, our results suggest that uterine cancer survival might be superior in high-volume hospitals in Osaka, Japan.