Assessing the benefits of testing for breast cancer susceptibility genes: a decision analysis.

Tests for the presence of mutations of genes BRCA1 and BRCA2 are increasingly available. Genetic testing creates dilemmas for women and men who regard themselves to be at high risk for breast cancer. Who will benefit from genetic testing? What is the benefit? Does testing improve quality of life? An important consideration in addressing these questions is the woman's chance of carrying a mutation at BRCA1 or BRCA2. Also important are the effectiveness and cost of the testing procedure, the availability of prophylactic interventions, the effectiveness and negative aspects of interventions, the impact of testing on other family members, and the impact of testing on the woman's ability to obtain insurance coverage. In this article we review the development of a statistical model for predicting whether a woman is a carrier of a BRCA1 or a BRCA2 mutation. We also show how this calculation can be used to assess the benefit of testing, and we quantify the size of the benefit in terms of its improvement on quality-adjusted life years (QALYs).