Journal Club - September 2004

Influence of hospital procedure volume on ovarian cancer survival in Japan, a country with low incidence of ovarian cancer.
Ioka A, Tsukuma H, Ajiki W, Oshima A.
Cancer Sci 2004; 95: 233-237. [Abstract]
http://cancer-sci.bcasj.or.jp/

Summary
This was a population-based study that was carried out to evaluate the potential association between survival of ovarian cancer patients and the volume of ovarian cancer surgery performed at hospitals in Japan. Overall, 2450 cases of ovarian cancer were identified between the study years of 1975 to 1995. Hospitals (n=208) were divided according the average annual number of ovarian cancer surgeries: high-volume (8.8 operations per year), medium-volume (4.0 operations per year), low-volume (2.0 operations per year), and very low-volume (0.3 operations per year). For all ovarian cancer patients, the 5-year relative overall survival rate was 38.8%.  Statistical analysis revealed that 5-year survival time was significantly correlated with hospital ovarian cancer surgical volume:  very low-volume hospital = 22.3%, low-volume hospital = 34.2%, medium-volume hospital = 46.2%, and high-volume hospital = 55.0%. After adjusting for potential confounding effects of other clinical variables, patients who received surgery for ovarian cancer at a very low-volume hospital had a 60% higher risk of death from ovarian cancer than patients operated on at high-volume hospitals.

Discussion
Important limitations of this study are a product of the blunt instrument population-based database used for the analyses. Specifically, the analysis did not include information on other medical problems, aside from ovarian cancer, that might have influenced survival, and staging information was unable to be verified. Strengths of the study include the large size of the population examined and the precision in categorizing the number of surgeries performed at each hospital.

Conclusion
These results provide further objective evidence that centralization of care for patients undergoing surgery for ovarian cancer in a high-volume center results in improved survival rates.  More information: Recent data from Johns Hopkins on ovarian cancer surgery rates in Maryland.

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