risk for local recurrence was 2.5 (if not specialty trained) and 1.8 (if a low-volume surgeon). The relative risks against disease-free survival were 1.5 and 1.4 for non-specialty-trained or low-volume surgeons, respectively.

In England, Sainsbury et al. (1995) assessed the effect of a surgeon's volume of cases on the five-year survival of 12,861 women with breast cancer treated with "curative" surgery between 1979 and 1988 in Yorkshire, England (population 3.6 million). There was no difference in survival between patients treated by surgeons seeing <10 and 10-29 cases per year, but if the surgeons saw >30 cases per year, the adjusted risk of death at five years was 0.85 (C.I. 0.77-0.93). About 50 percent of patients were seen by high-volume (>30 cases) surgeons. After controlling for case mix and clinical variables (e.g., axillary node status, histologic grade), variation among the consultants accounted for about an absolute 8 percent difference in survival. This benefit was principally associated with the greater use of chemotherapy.

The evidence on the effects of specialization, either by hospitals or by physicians, does not present a consistent picture; most, but not all, studies show improved care with specialization. Findings from these observational studies must be interpreted with caution because they are highly subject to bias. Patients cared for by specialty providers and specialty centers differ from patients treated elsewhere, and analyses must account for these differences in case mix. Many studies do not appropriately control for important patient variables and clinical factors that likely vary by site of care. Specialty providers such as those in teaching hospitals differ from community-based providers in their use of staging procedures, which could contribute to a stage migration bias that favors specialists.

Managed Care Versus Fee-For-Service Care

There is a great deal of interest in the way patients with chronic illnesses such as cancer fare within managed care organizations (see definition and discussion of managed care in Chapter 2). Theoretically, quality of care could be compromised if individuals enrolled in managed care plans could not access needed cancer care specialists or services. On the other hand, care could be enhanced if managed care plans implemented effective early detection, clinical practice guidelines, or disease management programs to a greater extent than FFS plans. Although intriguing questions have been raised, there is little evidence on which to judge the impact of managed care on the quality of cancer care. Individuals enrolled in managed care plans are generally satisfied with the care that they receive, and in one study, Medicare beneficiaries in managed care did not have high rates of switching into FFS plans after a cancer diagnosis (Riley et al., 1996). This does not necessarily mean that beneficiaries were entirely satisfied with care, but that any dissatisfaction does not seem to lead to high levels of disenrollment.

HMO enrollees as compared to those in FFS settings receive more cancer screening services (see Chapter 3). Only eight studies have looked directly at the effect of managed care on cancer care. Riley et al. (1999) recently examined treatment for early breast cancer between 1988 and 1993 among elderly women receiving care in HMO and FFS settings in 11 U.S. geographic areas. Use of breast conserving surgery was similar among women with early-stage disease enrolled in HMO and FFS plans (38 and 37 percent, respectively). Among women undergoing



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