Understanding Benign Breast Disease and Subsequent Breast Cancer in Hispanic White Females: A Step Closer to Evidence-Based Management.

INTRODUCTION: Although Hispanic White (HW) females have a lower incidence of breast cancer than non-Hispanic White (NHW) females, breast cancer risk is unclear for HW females after benign breast disease (BBD). METHODS: We compared BBD characteristics and subsequent breast cancer risk among HW and NHW females in New Mexico using a population-based collection of benign breast biopsies (1996-2007). BBD was categorized as nonproliferative disease (NPD), proliferative disease without atypia (PDWA), or atypical hyperplasia (AH). Breast cancer risk was assessed as absolute risk (AR) using cumulative incidence and RR by comparing the number of breast cancer events in BBDs to non-BBD. RESULTS: This study included 3,684 HW and 6,587 NHW females with BBD. HW females had similar proportions of NPD (58.6% vs. 54.3%), PDWA (21.4% vs. 23.5%), and AH (3.6% vs. 3.3%) as NHW females. Breast cancer risk among all females with BBD was higher than population-based expected rates (RR, 1.87) and was similar for HW and NHW subgroups (RR = 1.99 vs. 1.84). As expected, breast cancer risk increased with increasing BBD severity, both overall [RR, 1.81 (NPD), 1.85 (PDWA), and 3.10 (AH)] and in the HW and NHW subgroups. Adjusted AR of breast cancer at 5 years also increased with the severity of BBD (HW vs. NHW; NPD: 1.4% vs. 2.1%; PDWA: 1.5% vs. 2.7%; AH: 6% vs. 4.8%). CONCLUSIONS: We found similar breast cancer RRs and ARs in HW and NHW. Risk counseling should ensure that HW females receive breast cancer clinical management warranted by their similar absolute risks. IMPACT: The present population-based provides evidence for the clinical management of HW females with BBD for the prevention of breast cancer.

Obesity and survival among a cohort of breast cancer patients is partially mediated by tumor characteristics.

Obesity exerts adverse effects on breast cancer survival, but the means have not been fully elucidated. We evaluated obesity as a contributor to breast cancer survival according to tumor molecular subtypes in a population-based case-cohort study using data from the Surveillance Epidemiology and End Results (SEER) program. We determined whether obese women were more likely to be diagnosed with poor prognosis tumor characteristics and quantified the contribution of obesity to survival. Hazard ratios (HRs) and 95% confidence intervals (CI) were calculated via Cox multivariate models. The effect of obesity on survival was evaluated among 859 incident breast cancers (subcohort; 15% random sample; median survival 7.8 years) and 697 deaths from breast cancer (cases; 100% sample). Obese women had a 1.7- and 1.8-fold increased risk of stage III/IV disease and grade 3/4 tumors, respectively. Obese women with Luminal A- and Luminal B-like breast cancer were 1.8 (95% CI 1.3-2.5) and 2.2 (95% CI 0.9-5.0) times more likely to die from their cancer compared to normal weight women. In mediation analyses, the proportion of excess mortality attributable to tumor characteristics was 36.1% overall and 41% and 38% for Luminal A- and Luminal B-like disease, respectively. Obesity was not associated with breast cancer-specific mortality among women who had Her2-overexpressing or triple-negative tumors. Obesity may influence hormone-positive breast cancer-specific mortality in part through fostering poor prognosis tumors. When tumor biology is considered as part of the causal pathway, the public health impact of obesity on breast cancer survival may be greater than previously estimated.

The impact of cytochrome P450 2D6 metabolism in women receiving adjuvant tamoxifen.

BACKGROUND: Tamoxifen is biotransformed to the potent anti-estrogen, endoxifen, by the cytochrome P450 (CYP) 2D6 enzyme. CYP2D6 genetic variation and inhibitors of the enzyme markedly reduce endoxifen plasma concentrations in tamoxifen-treated patients. Using a North Central Cancer Treatment Group adjuvant tamoxifen trial, we performed a comprehensive evaluation of CYP2D6 metabolism by assessing the combined effect of genetic variation and inhibition of the enzyme system on breast cancer recurrence and death. METHODS: Medical records were reviewed at each randomizing site to determine whether CYP2D6 inhibitors were co-prescribed with tamoxifen. Extensive metabolizers were defined as patients without a *4 allele (i.e., wt/wt) who were not co-prescribed a CYP2D6 inhibitor. Patients with decreased CYP2D6 metabolism were classified as intermediate or poor metabolizers (PM) based on the presence of one or two CYP2D6*4 alleles or the co-administration of a moderate or potent CYP2D6 inhibitor. The association between CYP2D6 metabolism and clinical outcome was assessed using Cox modeling. RESULTS: Medication history was available in 225/256 eligible patients and CYP2D6*4 genotype in 190 patients. Thirteen patients (6%) were co-prescribed a CYP2D6 inhibitor [potent (n = 3), moderate (n = 10)], resulting in the following CYP2D6 metabolism: extensive (n = 115) and decreased (n = 65). In the multivariate analysis, patients with decreased metabolism had significantly shorter time to recurrence (p = 0.034; adj HR = 1.91; 95% CI 1.05-3.45) and worse relapse-free survival (RFS) (p = 0.017; adj HR = 1.74; 1.10-2.74); relative to patients with extensive metabolism. Cox' modeling demonstrated that compared to extensive metabolizers, PM had the most significant risk of breast cancer relapse (HR 3.12, p = 0.007). CONCLUSION: CYP2D6 metabolism, as measured by genetic variation and enzyme inhibition, is an independent predictor of breast cancer outcome in post-menopausal women receiving tamoxifen for early breast cancer. Determination of CYP2D6 genotype may be of value in selecting adjuvant hormonal therapy and it appears CYP2D6 inhibitors should be avoided in tamoxifen-treated women.

A two-gene expression ratio of homeobox 13 and interleukin-17B receptor for prediction of recurrence and survival in women receiving adjuvant tamoxifen.

PURPOSE: In the adjuvant treatment of estrogen receptor (ER)-positive breast cancer, additional markers are needed to identify women at high risk for recurrence. EXPERIMENTAL DESIGN: We examined the association between the ratio of the homeobox 13 (HOXB13) to interleukin-17B receptor (IL-17BR) expression and the clinical outcomes of relapse and survival in women with ER-positive breast cancer enrolled onto a North Central Cancer Treatment Group adjuvant tamoxifen trial (NCCTG 89-30-52). RESULTS: Tumor blocks were obtained from 211 of 256 eligible patients, and quantitative reverse transcription-PCR profiles for HOXB13 and IL-17BR were obtained from 206 patients. The cut point for the two-gene log 2(expression ratio) that best discriminated clinical outcome (recurrence and survival) was selected and identified women with significantly worse relapse-free survival (RFS), disease-free survival (DFS), and overall survival (OS), independent of standard prognostic markers. The cut point differed as a function of nodal status [node negative (59th percentile) versus node positive (90th percentile)]. In the node-positive cohort (n = 86), the HOXB13/IL-17BR ratio was not associated with relapse or survival. In contrast, in the node-negative cohort (n = 130), a high HOXB13/IL-17BR ratio was associated with significantly worse RFS [hazard ratio (HR), 1.98; P = 0.031], DFS (HR, 2.03; P = 0.015), and OS (HR, 2.4; P = 0.014), independent of standard prognostic markers. CONCLUSION: A high HOXB13/IL-17BR expression ratio is associated with increased relapse and death in patients with resected node-negative, ER-positive breast cancer treated with tamoxifen and may identify patients in whom alternative therapies should be studied.