self-report, survey of the treating physician, and the medical record, Guadagnoli et al. (1997) found that 92 percent of women with node-positive breast cancer received some form of adjuvant therapy. Although the likelihood of women with node-positive breast cancer receiving adjuvant therapy did appear to decline slightly with age, this was not statistically significant. The use of adjuvant therapy did decline in women with node-negative breast cancer, and this was true for both chemotherapy and hormone therapy: 73 percent of women 50 to 59 years old with node-negative breast cancer received adjuvant therapy compared with 67 percent of women age 60 to 69, 56 percent of women age 70 to 79, and 36 percent of women age 80 and older. However, these age-associated differences were not significant after adjusting for marital status, education, income, HMO membership, tumor size, lymphatic invasion, estrogen receptor status, grade, type of primary surgery, history of breast and other cancer, and severity of comorbid disease. The use of adjuvant hormone therapy in node-negative disease also declined to 34 percent in women age 80 and older from only 52 percent in the other age groups. Since the authors did not stratify on tumor size or estrogen receptor status, it cannot be determined if the subset of women with node-negative disease, but larger tumors, were more likely to receive adjuvant therapy, which would suggest that care was being provided in a manner consistent with the scientific evidence and medical consensus of the time.
This last study by Guadagnoli et al. (1997) reports appropriately high rates of adjuvant therapy and thus contradicts the other studies, which suggest that problems exist with the quality of care provided for elderly women with breast cancer in the United States (Ballard-Barbash et al., 1996; Farrow et al., 1992; Goodwin et al., 1993; Greenfield et al., 1987; Hillner et al., 1996; Lazovich et al., 1991). Of note, the Guadagnoli et al. (1997) study uses multiple data sources, including patient self-report, physician report, and the medical record, to obtain information about treatment. All of the authors who report poorer adherence to standard treatment in elderly patients, with the exception of Greenfield et al. (1987), used cancer registry data, which again raises the issue of the reliability of cancer registry data on processes of care. Another possible explanation for the higher rates of adjuvant therapy in the elderly in the study by Guadagnoli et al. (1997) is that the quality of care has improved over time; they report data from 1993, whereas the other studies include data from 1980-1986. Perhaps with the dissemination of the results of clinical trials performed in the 1980s, the use of adjuvant therapy and radiation therapy in the elderly after breast conserving surgery has increased appropriately. Alternatively, there may be regional variations in the quality of care that explain discrepancies in the results of these studies. Minnesota may have better-quality care for breast cancer than the rest of the United States. In any case, given the preponderance of data suggesting that compliance with standard therapy for breast cancer in older women in the United States is low, even in the face of an isolated study showing excellent quality of care in 30 hospitals in Minnesota, these results highlight potential problems in the quality of breast cancer care that warrant further investigation.
Evidence from the late 1980s suggests that some hospitals were providing poorer quality breast cancer care than others. In a study conducted in 1988 by Hand et al. (1991), the interquartile range (25th to 75th percentile) for hospitals in Illinois that did not provide radiation therapy after breast conserving surgery was 17 to 75 percent (Hand et al., 1991). For those not providing adjuvant therapy the interquartile range was 30 to 56 percent, and for those not performing an estrogen receptor test on the pathologic specimen it was 4 to 14 percent.
In conclusion, studies of processes of care that have compared rates of radiation therapy after breast conserving surgery and adjuvant therapy for locally advanced breast cancer suggest