Revisiting breast cancer patients who previously tested negative for BRCA mutations using a 12-gene panel.

PURPOSE: BRCA mutations contribute to about 20% of all hereditary breast cancers. With full-genome sequencing as the emerging standard for genetic testing, other breast cancer susceptibility genes have been identified and may collectively contribute to up to 30% of all hereditary breast cancers. We re-assessed women who had previously tested negative for a BRCA mutation when outdated techniques were used, and discuss the implications of identifying a mutation several years after initial genetic testing. METHODS: We evaluated the prevalence of mutations in 12 breast cancer susceptibility genes (including BRCA1 and BRCA2) in 190 breast cancer patients with a strong family history of breast cancer. These women had previously tested negative for mutations in the large coding exons of BRCA1 and BRCA2 using the protein truncation test (PTT) between the years of 1996 and 2013. RESULTS: We identified pathogenic mutations in 17 of 190 (9%) women. Six mutations were detected in BRCA1 (n = 2) and BRCA2 (n = 4). Eleven mutations were found in other breast cancer susceptibility genes including CHEK2 (n = 5), PALB2 (n = 2), BLM (n = 2), ATM (n = 1) and TP53 (n = 1). CONCLUSION: Among 190 breast cancer patients with a family history of the disease, and who previously received a negative result for BRCA mutations using the PTT, 17 (9%) women were found to carry a high-risk pathogenic mutation in a breast cancer susceptibility gene. Six of these women were BRCA mutation carriers who were missed previously. These findings support the rationale for updated genetic testing in patients who tested BRCA mutation negative using outdated techniques.

Prospective study of high-risk, BRCA1/2-mutation negative women: the 'negative study'.

BACKGROUND: We previously reported that women from high-risk families who tested negative for a BRCA1 or BRCA2 (BRCA1/2) mutation were four times more likely to develop breast cancer compared to women in the general population. Preventive measures and risk factors for breast cancer development in these high-risk women have not been evaluated to the same extent as BRCA1/2 positive women. Further, there is virtually no scientific evidence about best practices in their management and care. The proposed study will examine a role of genetic and non-genetic factors and develop the systems and parameters for the monitoring and surveillance necessary to help establish guidelines for the care of this high-risk population. METHODS/DESIGN: To achieve our goals, we will assemble and follow a Canadian cohort of 1,000 cancer-free women with a strong family history breast cancer (defined as two or more relatives affected by breast cancer under the age of 50, or three or more relatives diagnosed with breast cancer at any age from one side of the family and with no BRCA1/2 mutation in the family). All eligible participants will be mailed a study package including invitation to participate, consent form, a research questionnaire to collect data regarding family history, reproductive and lifestyle factors, as well as screening and surgery. Usual dietary intake will be assessed by a diet history questionnaire. Biological samples including toenail clippings, urine and blood samples will be collected. These women will be followed every two years by questionnaire to update exposure information, screening practices, surgical and chemoprevention, and disease development. DISCUSSION: Findings from this study will serve to help establish clinical guidelines for the implementation of prevention, counseling, and treatment practices for women who face an elevated risk of breast cancer due to family history, but who do not carry a BRCA1/2 mutation.

Relationship between Caffeine and Levels of DNA Repair and Oxidative Stress in Women with and without a BRCA1 Mutation.

BACKGROUND: Coffee consumption has been associated with a reduction in breast cancer risk among women with a BRCA1 mutation. The objective of this study was to evaluate whether major contributors of caffeine intake are associated with a reduction in DNA damage and/or oxidative stress in women with and without a BRCA1 mutation. METHODS: Coffee, tea, soda and total caffeine consumption was collected by a dietary history questionnaire, and DNA repair capacity in lymphocytes was assessed by the comet assay (tail moments), micronucleus test (per 1,000 binucleated cells) and analysis of γ-H2AX staining (nuclear foci). The thiobarbituric acid-malondialdehyde and DTNB assays were used to estimate serum lipid peroxidation (µmol/l) and protein oxidation (µmol/l), respectively. RESULTS: Among all women, high levels of caffeine and caffeinated coffee intake were associated with significantly lower levels of micronuclei (138.50 vs. 97.67, p = 0.04, and 138.12 vs. 97.70, p = 0.04). There was no significant relationship between caffeine, coffee, tea and soda intake and the other markers of DNA repair capacity and oxidative stress among all women and in analyses stratified by BRCA1 mutation status. CONCLUSION: The chemopreventive effects of coffee and/or caffeine may be associated with improved capacity to efficiently repair DNA damage.

The effect of oral 3,3'-diindolylmethane supplementation on the 2:16α-OHE ratio in BRCA1 mutation carriers.

Hormonal exposures are known to influence breast cancer risk among women with a BRCA1 mutation. Thus, dietary factors that increase the 2-hydroxyestrone (OHE):16α-OHE ratio, a biomarker inversely related to breast cancer development, may also influence cancer risk. We conducted a dietary intervention study to evaluate the ability of 300 mg/day of 3,3'-diindolylmethane (DIM) to increase the urinary 2:16α-OHE ratio in 20 women with a BRCA1 mutation. BRCA1 mutation carriers (n = 15) were assigned to receive 300 mg/day of Rx Balance BioREsponse DIM for 4-6 weeks (intervention group) and five BRCA1 mutation carriers did not take DIM (control group). The urinary 2:16α-OHE ratio was assessed at baseline and after 4-6 weeks by immunoassay. There was no significant effect of DIM on the 2:16α-OHE ratio (2.4 at baseline vs. 3.0 after the intervention, P = 0.35). A short dietary intervention with DIM did not significantly increase the 2:16α-OHE ratio in female BRCA1 mutation carriers. Larger studies investigating the effect of dietary or lifestyle interventions on circulating hormone levels in these high-risk women are warranted.