[Determining factors for adjuvant treatment of breast cancer in the Côte d'Or region 1982-1990. Registry of gynecologic cancers at the Côte d'Or].

In the search for changing medical practices, this population-based study dealt with the breakdown of adjuvant systemic breast cancer treatments from 1982 to 1990. The 1,760 women recorded by the cancer registry of the French Côte d'Or region (241,020 women in 1990) during 1982-1990, who were found to have both a non metastatic breast invasive carcinoma and a no perceptible residual disease after locoregional treatment completion were the subjects of this analysis. Forty percent of the patients received adjuvant treatment: 17% only had chemotherapy, 7% had chemotherapy associated with hormonal therapy and 16% only had hormonal therapy. Chemotherapy was the only adjuvant treatment for the patients under 35 years of age. Hormonal therapy was the main treatment for the patients over 74. For patients from 35 to 74 with a non-inflammatory tumour, the determination of adjuvant treatment was multifactorial. For each modality of adjuvant treatment, the logistic regression model provided an assessment of the contribution of each independant variable to the risk of being treated. This method has focused on period effect after adjustment on the tumor and patient characteristics. Adjuvant treatments were more widely used in the late 1980s than in the early 1980s (OR = 1.9; p = 0.006). On the one hand, the use of chemotherapy-hormonal therapy association remained stable and the use of chemotherapy decreased with a boundary significance (OR = 0.6; p = 0.056); on the other hand, the use of hormonal therapy dramatically increased and was 3.5 times as high for the period 1988-1990 as for the period 1982-1984 (OR = 3.5, p < 0.0001). Comprehensive study of survival trends after breast cancer should take into account the adjuvant systemic treatments and the conditions of their indications to separate their potential beneficial effects from the effects of lead time bias. Necessity of treatment indicator quality control was emphasised.