positive tumors, regardless of the patient's age (Fisher et al., 1997). These studies demonstrate improved breast cancer outcomes with chemotherapy, tamoxifen, and perhaps both treatments together in all patients. However, given that the absolute benefit is extremely small in patients with a good prognosis (2 percent improvement in 10-year survival for low-risk patients), the benefits may not outweigh the risks of adjuvant treatment in these patients (Osborne et al., 1996). So although most experts would agree that all women with involved lymph nodes, large tumors, and even moderate-size tumors should receive adjuvant therapy, whether it is essential to offer treatment to women with extremely small tumors has not yet been clearly established. Thus, despite clear evidence of process-outcomes links for adjuvant therapy in breast cancer, the determination of whether all patients should be treated remains an issue of expert judgment and consensus. If adjuvant chemotherapy is administered, the quality of treatment can be evaluated by assessing whether an adequate dose of chemotherapy is given (Bonadonna, 1985).

Relatively few studies examine the full spectrum of cancer care. Hillner evaluated multiple dimensions of care for 983 nonelderly women diagnosed between 1989-1991 with early breast cancer and insured by Virginia Blue Cross/Blue Shield (BC/BS) according to a 12-point scorecard with target values set according to expert opinion (Table 4.4). Some procedures appeared to be overused (e.g., perioperative bone scans), while others were underused (e.g., breast conserving surgery, visit to medical oncologist to discuss adjuvant therapy). Claims for at least one cycle of chemotherapy were found for 83 percent of premenopausal, node-positive women.

Variations in Rates of Breast Conserving Surgery. Many studies have compared the proportion of women who receive breast conserving surgery (BCS) instead of mastectomy. The decision about which type of breast surgery to undergo depends on the size of the primary tumor, the skill and preferences of the surgeon, and the preferences of the patient. The proportion of women who would choose breast conserving surgery if they were presented with enough information to make an informed choice is not known. Since there is no benchmark for what percentage of women should receive breast conserving surgery, whether any identified variation in the rates of conservative surgery is associated with the quality of care cannot be ascertained. However, widespread differences in the percentage of women who receive the two types of surgery would suggest that some women are not able to completely exercise their choice.

The proportion of women who receive breast conserving surgery versus mastectomy as the primary surgical treatment for early breast cancer varies dramatically by region of the country, according to studies conducted in the 1980s after the results of randomized controlled trials demonstrating the equivalency of the two procedures were published. The proportion of all women 65 and older with early breast cancer who received breast conserving surgery ranged from 4 percent in Kentucky to 21 percent in Massachusetts in 1986 according to Medicare data (Nattinger et al., 1992). Across the nine areas with SEER registries, Seattle appeared to have the highest rates of breast conserving surgery in 1983-1989 with 34 percent of women with Stage I and II disease receiving BCS (Farrow et al., 1992; Lazovich et al., 1991; Samet et al., 1994). The national overall rates of breast conserving surgery among Medicare patients with nonmetastatic disease changed little between 1986 and 1990 (from 14.1 to 15.0 percent) (Nattinger et al., 1996). Although patient age, the sociodemographic characteristics of communities, hospital characteristics, and the availability of radiation therapy appear to affect the proportion of women who undergo breast conserving surgery, marked geographic variation in the use of the procedure persists even after adjusting for these characteristics (Farrow et al., 1992; Lazovich et al., 1991; Nattinger

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