Background: It has been postulated that one of the rewards of breast cancer screening is the increased likelihood of receiving breast-conserving surgery. The recent wide application of screening mammography has led to an acceleration in the otherwise gradual shift toward smaller, earlier-stage breast cancer that has been occurring since the turn of the century.
Methods: We examined data from patients with pathologically diagnosed breast cancers from all general hospitals in the state of Vermont for use of breast-conserving surgery by era (1975-1984 [n = 1,652] versus 1989-1990 [n = 683]), method of cancer detection, age, clinical tumor-node-metastases (cTNM) stage, pathologic size, and node status.
Results: Cancers detected by mammography were 2% in 1975-1984 and 36% in 1989-1990. Invasive breast cancers < 2 cm maximum pathologic diameter were 34% in 1975-1984 and 50% in 1989-1990 (p < 0.001). Statewide, the use of breast-conserving surgery for invasive cancer increased from 8.6% in 1975-1984 to 42.9% in 1989-1990 (p < 0.001). In 1989-1990 at the single university hospital, 73% of the patients were treated with breast-conserving surgery versus 22% at the community hospitals (range 0-39%, p < 0.001). Differential referral patterns related to stage and age did not appear to explain the variation, because the percentages of cTNM stage I and II patients at the university hospital were similar to those of the community hospitals. Using the university hospital as the standard, we estimated that at least 67% of all patients in the state were eligible for breast-conserving surgery in the years 1975-1984 and 73% in the years 1975-1984, a 6% increase.
Conclusions: Most of the variation in breast-conserving surgery was related to factors other than patient age and stage of disease. Variation was probably related more to local community factors and physician attitudes. At least two-thirds of the women in the state were eligible for breast-conserving surgery even before the wide use of mammography screening.