ABSTRACT
BACKGROUND: CYP2D6 is a critical enzyme in the metabolism of tamoxifen and potentially a key determinant in breast cancer outcomes. Our study examined patients' beliefs about how the CYP2D6 genotype would affect their prognoses. METHODS: Women enrolled in a pharmacogenomic clinical trial and on tamoxifen for prevention or treatment of breast cancer underwent CYP2D6 genotyping (EM = extensive, IM = intermediate, PM = poor metabolizing alleles). The informed consent said that the purpose of the trial was to examine effects of dose adjustment based on genotype, but that clinical benefits were uncertain. Our embedded sub-study surveyed 320 patients prior to receiving their genotypes. We experimentally manipulated 6 vignettes to describe hypothetical tamoxifen treatment (no or yes) and hypothetical genotype (EM, IM or PM). For each vignette, women gave their perceived recurrence risk (RR; 0-100%). RESULTS: Women believed that genotype would not affect their RR if they did not take tamoxifen (p = 0.06). However, women believed that if prescribed tamoxifen, genotype would affect their RR (22% if EM, 30% if IM and 40% if PM, p < 0.001). CONCLUSION: Women believed that extensive tamoxifen metabolizers had better prognoses, despite study materials stating uncertainty about any benefit. The rapidly changing nature of genomic science calls for caution when communicating clinical utility.
Subject(s)
Breast Neoplasms/psychology , Cytochrome P-450 CYP2D6/genetics , Health Knowledge, Attitudes, Practice , Neoplasm Recurrence, Local/psychology , Patient Education as Topic/methods , Pharmacogenetics , Antineoplastic Agents, Hormonal/therapeutic use , Breast Neoplasms/drug therapy , Breast Neoplasms/genetics , Cytochrome P-450 CYP2D6/metabolism , Female , Genotype , Humans , Middle Aged , Neoplasm Recurrence, Local/drug therapy , Neoplasm Recurrence, Local/genetics , Prognosis , Tamoxifen/therapeutic useABSTRACT
BACKGROUND/AIMS: Our study examined whether patient characteristics, beliefs and decision-making styles were associated with uptake of genomic testing for breast cancer recurrence risk. METHODS: Participants were 132 early-stage breast cancer patients eligible for the Oncotype DX genomic test. We interviewed patients in 2009-2010 and obtained information from medical charts. RESULTS: Half of the women eligible for genomic testing for breast cancer recurrence risk received it. The most common reason for not getting the test was that women's physicians did not offer it (80%). Test recipients were more likely to be unsure about receiving chemotherapy treatment compared to women who did not receive the test (p < 0.05). Women who received the test had less advanced disease pathologies, recalled a lower objective recurrence risk, perceived lower recurrence risk, and were slightly younger (all p < 0.05). Most women who described their decision-making style as active received the test (75%), whereas few women who described their style as passive received the test (12%) (p < 0.01). CONCLUSION: In the university clinic we studied, genomic testing appeared to be more common among patients who may benefit most from the information provided by results, but confirmation in larger studies is needed.
