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Adjusted Risk Ratios for Death for Breast Cancer Patients Hospitalized in New York State, by Hospital Volume, 1984-1989
Hospital Volume (no. of surgeries per year)
No. of Patients
Percentage of Total Patients
95% Confidence Interval
SOURCE: Roohan et al., 1998.
Breast Cancer Surgery
Roohan and colleagues report on the effect of hospital volume of breast cancer surgical cases on the five-year survival of 47,890 women (white and black) treated for breast cancer in New York from 1984 to 1989, identified through hospital discharge data and linked to the New York State cancer registry (Roohan et al., 1998). At five years, patients from very low-volume hospitals (1-10 surgeries per year) had a 60 percent greater risk of all-cause mortality than patients from high-volume hospitals (150+ surgeries per year), after controlling for surgery type (mastectomy, limited surgery), patient age, cancer stage, comorbidity, race, socioeconomic status (census tract level), and distance to hospital. A gradient of risk was evident by volume category. Nearly one-third of patients (32 percent) were seen in the lower-volume hospitals (i.e., those with 50 or fewer surgical cases) (Table 5.9). The authors speculate that high-volume hospitals are more likely than others to provide effective postsurgical adjuvant treatments that have been shown to improve survival, perhaps because of better coordination of or access to these services (Roohan et al., 1998).
Processes of breast cancer care were examined in a 1988 study of 5,766 newly diagnosed breast cancer patients in Illinois. Hospitals with low compared to high breast cancer case volumes were less likely to use indicated radiation therapy after partial mastectomy (for Stages I and II), but were not less likely to use hormone receptor tests (for Stages II through IV) (Hand et al., 1991).
Evidence on The Volume-Outcome Relationship from Other Countries
Studies from other countries support the finding that high volume leads to better outcomes.
Scotland. Centralized treatment at high-volume centers improved outcomes for a type of testicular cancer (non-seminomatous germ cell tumors), even when controlling for participation in a protocol (although protocol treatment explained a large part of the variation) (Harding et al., 1993).