BRCA1/2 Variants and Metabolic Factors: Results From a Cohort of Italian Female Carriers

Left ventricular global longitudinal strain is worse in BRCA mutation positive breast cancer patients prior to cancer treatment and premature menopause

PURPOSE

Breast cancer patients with mutations in human tumor suppressor genes BRCA1 and BRCA2 are at higher risk of cardiovascular disease (CVD) than the general population, as they are frequently exposed to cardiotoxic chemotherapy, anti-estrogen therapy, radiation, and/or oophorectomy for cancer-related treatment and prophylaxis. Animal and cell culture models suggest that BRCA mutations may play an independent role in heart failure. We sought to evaluate cardiac structure and function in female BRCA1 and BRCA2 mutation carriers with breast cancer compared to BRCA wildtype women with breast cancer.

METHODS

We performed a 1:2 age- and hypertension-matched retrospective cohort study comparing BRCA1 and BRCA2 mutation carriers (n = 38) versus BRCA wildtype controls (n = 76) with a new diagnosis of breast cancer. Echocardiographic data were obtained within 6 months of breast cancer diagnosis and prior to chemotherapy, anti-estrogen therapy, radiation, or oophorectomy. Left ventricular global longitudinal strain (LV-GLS), a highly sensitive marker of LV function, was measured using QLab 15 (Philips Healthcare).

RESULTS

In the total cohort of 114 patients with a new diagnosis of breast cancer, the median age was 45 ± 11 years and the prevalence of hypertension was 8%. There were no differences in traditional cardiovascular disease risk factors between cases and controls. BRCA carriers had lower LV-GLS (- 18.1% ± 4.7% vs. - 20.1% ± 3.8%, p = 0.02) and greater right atrial area (12.9 cm2 ± 2.7 cm2 vs. 11.8 cm2 ± 2.0 cm2, p = 0.04) compared to controls; however, both LV-GLS and right atrial area were within the normal range. Compared to controls, BRCA carriers had a trend toward worse LV posterior wall thickness (0.89 cm ± 0.15 cm vs. 0.83 cm ± 0.16 cm, p = 0.06) although not statistically significant.

CONCLUSION

In women with newly diagnosed breast cancer and prior to treatment, LV-GLS was worse in BRCA1 and BRCA2 mutation carriers compared to those with BRCA wildtype. These findings suggest that BRCA mutations may be associated with subtle changes in cardiac function. Whether differences in GLS translate to increased cardiovascular risk in women with BRCA mutations needs to be further characterized.

The Impact of Mediterranean Dietary Intervention on Metabolic and Hormonal Parameters According to BRCA1/2 Variant Type

The female carriers of BRCA1/2 pathogenic variants (mutations) face a high lifetime risk of developing breast and/or ovarian cancer. However, the risk may differ depending on various genetic and non-genetic elements, including metabolic and hormonal factors. We previously showed that a 6-month Mediterranean dietary intervention trial reduced body weight and the levels of insulin-like growth factor I and other metabolic factors in BRCA mutation carriers. We also found that higher baseline levels of glucose and insulin were significantly associated with BRCA loss-of-function (LOF) variants. In this study, we evaluated whether the BRCA mutation type influences in a different way the metabolic and hormonal response to the dietary intervention in 366 female carriers. The LOF variant carriers randomized in the intervention group (IG) showed significantly higher changes in most considered parameters compared to the control group (CG). The nonsynonymous variant carriers in the IG showed similar changes, but none of them were statistically significant. Performing the “delta” analysis of differences (intention-to-treat analysis), we observed that in LOF variant carriers, the reduction of insulin levels was significantly more pronounced that in nonsynonymous variant carriers. These findings suggest that the changes in insulin levels might be modulated by a different response to the dietary intervention mediated by BRCA LOF variants.

BRCA1: An Endocrine and Metabolic Regulator

The breast and ovarian cancer susceptibility gene (BRCA1) is a tumor suppressor whose mutation has been associated with the development of breast, ovarian and, probably, other malignancies at young ages. The BRCA1 gene product participates in multiple biological pathways including the DNA damage response, transcriptional control, cell growth and apoptosis. Inactivating germline mutations of the BRCA1 gene can be detected in a substantial portion of families with inherited breast and/or ovarian cancer. While the genomic and cancer-related actions of BRCA1 have been extensively investigated, not much information exists regarding the cellular and circulating factors involved in regulation of BRCA1 expression and action. The present review article dissects the emerging role of BRCA1 as an important regulator of various endocrine and metabolic axes. Experimental and clinical evidence links BRCA1 with a number of peptide and steroid hormones. Furthermore, comprehensive analyses identified complex interactions between the insulin/insulin-like growth factor-1 (IGF1) signaling axis and BRCA1. The correlation between metabolic disorders, including diabetes and the metabolic syndrome, and BRCA1 mutations, are discussed in this article.