of quality of care, information would have to be obtained by patient self-report since this level of detail is not contained in cancer registries, claims, or medical records.

Receipt of Radiation, Adjuvant Chemotherapy, or Hormone Therapy Following Breast Conserving Surgery. Women who undergo breast conserving surgery should receive radiation therapy after surgery. Rates of radiation therapy after BCS suggest that in some parts of the United States, many women are not receiving needed radiation. In the nine SEER registry areas, the percentage of women receiving radiation therapy after breast conserving surgery in 1985-1986 had increased from 1983 to 1984, but still varied greatly (Farrow et al., 1992). Though Iowa had the greatest increase in the use of radiation therapy during this period, it still had the lowest use of all nine areas, with only 60 percent of women in 1985-1986 receiving radiation. Seattle had the highest use, with 81 percent in 1985-1986 receiving radiation therapy after breast conserving surgery. Although some women may refuse radiation therapy, one would hope that an informed discussion of the treatment options would lead many women who do not wish to receive radiation to choose mastectomy as their primary treatment. Thus, one might expect that only a small number of women would opt for breast conserving surgery without radiation.

A limitation of this study, and other studies that rely on cancer registry data, is that the validity of the data on treatment collected by the cancer registries has not been systematically evaluated. Thus, the low rates of radiation therapy after breast conserving surgery reported in this study may reflect incomplete data and not poor quality of care.

Alternatively, the low rates of radiation therapy after breast conserving surgery reported by Farrow et al. (1992) may reflect the practice in the 1980s but may not accurately describe the current quality of care in the United States. Two recently published studies of breast cancer care in selected populations suggest that the quality of care may have improved, at least for some women. Hillner et al. (1997) used 1989-1991 data from the Virginia Cancer Registry to evaluate the quality of care for 918 Virginia women age 64 or younger with Stage I-III breast cancer who had Blue Cross/Blue Shield health insurance. In this patient population, 82 percent of women who underwent breast conserving surgery received radiation therapy. In addition, 83 percent of women 50 and younger (who were assumed to be premenopausal) with node-positive disease received adjuvant chemotherapy. The authors were unable to assess the use of adjuvant hormone therapy through the claims data.

Guadagnoli et al. (1998a) compared the care received at 18 hospitals in Massachusetts by women diagnosed in 1993-1995 with Stage I or II breast cancer, with the care received at 30 hospitals in Minnesota by women diagnosed in 1993. In contrast to previous studies that relied on administrative data, these authors collected data about breast cancer treatment from medical records, patient surveys, and physician surveys. Among women treated at these institutions from 1993 to 1995, 84 percent in Massachusetts and 86 percent in Minnesota received radiation therapy after breast conserving surgery. In addition, 97 and 94 percent, respectively, of premenopausal women with node-positive breast cancer received adjuvant chemotherapy. By contrast, only 63 percent of postmenopausal women in Massachusetts and 59 percent in Minnesota who had positive lymph nodes and positive estrogen receptor status received adjuvant hormone therapy.

Another study (Young et al., 1996) used cancer registry data to examine the treatment of local breast cancer in Pennsylvania during 1986-1990, the time between that reported by Farrow et al. (1992) and by Hillner et al. (1997) and Guadagnoli et al. (1998a, b). This Study found that 82 percent of women received radiation therapy after breast conserving surgery. Of note, there



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