Understanding how breast cancer patients use risk information from genomic tests.

We sought to examine how patients' treatment decisions incorporate potentially conflicting information from standard clinical indicators (e.g., tumor size) and genomic tests for breast cancer recurrence risk. Participants were 77 early stage breast cancer survivors who previously received genomic testing. They read six hypothetical vignettes that varied recurrence risk indicated by standard tests (low or high risk) coupled with the genomic test (low, intermediate or high risk). For each vignette, women reported their perceived recurrence risk and treatment preferences. Test results indicating high recurrence risk increased perception of risk and preference for chemotherapy (p < .001 for all). Perceived risk explained (i.e., mediated) the effect of test results on chemotherapy preferences. When test results conflicted, women gave more weight to genomic over standard test results. Hypothetical genomic test results had the intended effect of influencing women's perceptions of recurrence risk and interest in chemotherapy.