OBJECTIVES:
Primary
* To identify genes associated with breast events (i.e., the occurrence of invasive breast cancer or ductal carcinoma in situ), in terms of single-nucleotide polymorphisms (SNPs) in a genome-wide association study, in Caucasian women at high risk of developing breast cancer who have received a selective estrogen receptor modulator (SERM) (i.e., tamoxifen or raloxifene) on the NSABP-P-1 OR NSABP-P-2 breast cancer prevention clinical trials.
* To determine the impact of CYP2D6 metabolizer status, which includes genotype and status of concurrent use of CYP2D6 inhibitors, on breast cancer events in participants receiving either tamoxifen or raloxifene.
Secondary
* To explore whether multiple SNPs within a region are independently associated with a breast event.
* To explore whether there are interactions among SNPs that increase the risk for a breast event.
* To explore whether there is interaction of any SNPs identified in the primary objective with randomized treatment, in terms of the risk for a breast event.
* To identify rare variants that might affect estrogen-dependent expression of chromosomes (CTSO) 4 and 16 (ZNF423) and/or the relationship to BRCA1 expression.
OUTLINE: Samples are stratified according to CYP2D6 genotype and CYP2D6 metabolizer status.
DNA extracted from previously collected blood samples is analyzed in a genome-wide association study and compared with 2 control samples from patients who did not experience a breast event. DNA samples are used to identify and analyze single nucleotide polymorphisms.
Also, exploratory analyses are conducted examining the impact of CYP2D6 metabolizer status on breast cancer events according to invasive vs non-invasive disease, ER status, PgR status, histologic type, and TMN stage.
