Menopausal Hormone therapy and Risk of Breast Cancer
One of the important questions plaguing most women during their middle age is whether they should opt for menopausal hormone therapy to alleviate menopausal symptoms.
Many women in this delicate phase count fretfully the number of sleepless nights, the night sweats and hot flashes that interrupt their otherwise normal life.
The U.S Centers for Disease Control and Prevention analyzed a 2015 National Health Interview survey (NHIS) and found that over 56% of perimenopausal women failed to get sufficient sleep.
The dwindling levels of estrogen has been associated with the classic symptoms of menopause, which led people to believe that menopausal hormone therapy could lower the intensity of symptoms.
This made estrogen supplementation very popular during the late 1960s with the belief that it could make women ‘young forever’.
FDA approval for estrogen therapy for osteoporosis helped gain confidence of more women, with observational studies conducted in 1990s showing reductions in coronary heart disease and Alzheimer’s.
The first study that raised an alarm about the use of menopausal hormone therapy and breast cancer risk was the Women’s Health Initiative study. This study found that for every 10,000 person-years of use of menopausal hormone therapy (MHT) use, there were 8 more invasive breast cancers.
So, what makes estrogen so harmful during menopause if women have been producing it for so many years?
Estrogen is a female hormone which is mostly produced in the ovaries. During breast development, the DNA present in the cells is constantly copied before the development of new breast cells.
This delicate process could increase the risk of development of genetic abnormalities.
Estrogen plays an important role in breast tissue development and supplementation with this hormone during menopause, therefore, has been shown to be associated with an increased risk for breast cancer.
The results of the Women’s Health initiative study led to a considerable drop in the use of hormone therapy in the U.S.
The assumption was that women would use it for a short period of time with the risk of breast cancer being uniform.
However, a large study conducted by the Breast Cancer Association Consortium on perimenopausal women showed that specific genetic variants modified the effect of hormone therapy use on the risk of breast cancer.
The study included a large sample size and three loci present on the chromosomes 13, 14 and 16 were found to alter breast cancer risk on menopausal hormone therapy use.
Women who had more than 5 or 6 high risk variants were found to have an 86% increased risk for breast cancer on MHT use while there was no association with breast cancer risk on MHT use among women with fewer than 2 risk variants.
The results of the study should stress the importance of identifying genetic variants and weighing the relief of symptoms against the unhealthy legacy of taking these medications.
You can now find out if you carry the variants associated with Menopausal hormone therapy and breast cancer risk from Xcode’s Breast Cancer report by uploading your 23andMe or any other Ancestry DNA raw data.
You can read more about the Xcode Breast Cancer report here.