Time trends in systemic adjuvant treatment for node-negative breast cancer

We conducted a population-based study in Quebec, Canada, to assess longitudinal changes in systemic adjuvant therapy for node-negative breast cancer.

A stratified random sample was selected among women with newly diagnosed node-negative breast cancer in 1988, 1991, and 1993. Information on the patient, her tumor, source of care, and treatment was abstracted from medical charts. Patients were classified as being at minimal, moderate, or high risk of recurrence on the basis of criteria proposed at the 4th International Conference on Adjuvant Therapy of Primary Breast Cancer (St. Gallen, Switzerland, 1992), and systemic adjuvant treatment received was dichotomized as being consistent or not consistent with consensus recommendations.

Overall, 1,578 cases of invasive breast carcinoma were reviewed. The proportion of patients who were given hormonal or cytotoxic treatment increased from 51.7% to 73.1% from 1988 to 1993. Virtually all women at minimal risk were treated in 1991 and 1993 according to the consensus statement. The proportions of women so treated were 75.0% and 65.4% in the moderate- and high-risk categories, respectively, in 1991. In 1993, these proportions were 71.4% and 67.0%, respectively. Omission of chemotherapy, especially in high-risk women with estrogen receptor-negative tumors who were 50 to 69 years of age, was the most frequent inconsistency with guidelines.

Systemic adjuvant therapy for node-negative breast cancer has gained acceptance. Better understanding of the decision-making process, of the perception of the risks and benefits involved, and of the impact of alternative strategies for the dissemination of consensus recommendations are needed to promote the use of chemotherapy in specific categories of women who are at high risk of recurrence.