BRCA and Breast Cancer

Estradiol levels are strongly associated with the risk of breast cancer in postmenopausal women. Estradiol is an estrogen steroid hormone naturally produced in the body. It is a major female sex hormone. According to a study, 36% of women with estradiol levels of more than 10 pmol/L had a 3% four-year risk of breast cancer. CYP19A1 gene produces the enzyme aromatase that regulates the levels of estradiol. Certain types of the CYP19A1 gene are associated with higher estradiol levels and an increased risk for breast cancer.

Around one percent of all breast cancer cases develop in men. A family history of breast cancer is the major risk factor for breast cancer in men. The relative risk of breast cancer for a woman who has an affected brother is approximately 30% higher than for a woman with an affected sister. Nearly 10% of male breast cancer cases are due to mutations in the BRCA2 gene. Mutations in the BRCA1 gene are reported less frequently for male breast cancer. CHEK2, PTEN, and PALB2 genes are some of the other genes studied.

With early detection and treatment, most cases of breast cancer have a good prognosis. According to the National Cancer Institute, 90 percent of women with breast cancer survive five years after diagnosis. However, there is considerable variation in survival due to genetic influence. The RAD51B gene is responsible for DNA repair. According to a study, low levels of RAD51B resulted in a 6% decrease in the survival rate. Other non-genetic factors like medical history, response to treatment, the type and stage of cancer, and the specific characteristics of cancer also influence the prognosis.

Bevacizumab is a drug commonly used in cancer treatments. It works by constricting the blood vessels to cut the blood flow to cancerous cells. Since the narrowing of blood vessels increases the pressure of blood flow in them, hypertension is a common complication of treatment with bevacizumab. In fact, research studies suggest that the development of hypertension could be predictive of improved clinical outcomes. Certain genetic factors increase the risk of hypertension when on bevacizumab therapy. Identifying these variants can help manage the adverse side effects of chemotherapy.

Breast size and its morphology is associated with the risk for breast cancer. The mammographic density (the non-fat breast tissue percentage) is also one of the risk factors for breast cancer. According to a study published in the International Journal of Cancer, lean women with larger breast size may have a higher likelihood of breast cancer. Genetic factors that influence breast development also play a role in breast cancer risk. A study identified seven single-nucleotide polymorphisms (SNPs) significantly associated with breast size, three of which have strong links to breast cancer.

Estrogen is called the female sex hormone is since it is responsible for the development of female reproductive organs. A cancer is called estrogen-receptor-positive (or ER-positive) if it has receptors for estrogen. Testing for hormone receptors is important to assess the response to hormonal therapy. Estrogen receptor-negative (ER-negative) cancers do not have the receptors to recognize estrogen and do not need estrogen to grow. Hence, hormonal therapy with estrogen may not be effective against these cancers. Certain genetic markers are associated with an increased risk of ER-negative breast cancer.

Estrogen is a sex hormone responsible for the development of female reproductive organs. It is also called the female sex hormone. A cancer is called estrogen-receptor-positive (or ER-positive) if it has receptors for estrogen. ER-positive breast cancer constitutes 80% of all breast cancers. Testing for hormone receptors is important to assess the response to hormonal therapy. Treatment options for ER-positive breast cancer involve reducing estrogen levels or stopping it from encouraging the growth of cancerous cells. Certain genetic markers are associated with an increased risk of ER-positive breast cancer.

Hair loss (Alopecia) is a distressing side-effect of chemotherapy—the drugs used in chemotherapy target the cancerous cells and the healthy hair follicle cells. According to a study, 8% of women refuse chemotherapy because of the risk of losing their hair. Most of the cytotoxic agents cause alopecia, but the severity in individual patients differ significantly. A research study identified four genes that play a role in hair loss during chemotherapy. CACNB4 gene, involved in calcium transport, showed the strongest association with hair loss. Analyzing these genes can help develop prevention strategies to manage chemotherapy-induced alopecia.

The hormone estrogen stimulates breast cell growth; prolonged exposure to estrogen can increase the risk for breast cancer. All women have lower levels of estrogen during the breastfeeding periods. This is because breastfeeding delays menstrual periods. The longer the breastfeeding duration, the lower the lifetime exposure to estrogen, which decreases the risk for breast cancer. Studies have estimated that the heritability of breastfeeding duration ranges from 44 to 54%. People with certain genetic types may tend to breastfeed their children for a longer duration than others.

According to a study published in the Journal of Adolescent Health, early-onset puberty in adolescent girls may increase their risk of developing breast cancer. The age of menarche or the first menstrual period influences your lifetime exposure to estrogen. There is considerable variation between the timing of puberty onset, with a mean of 4 to 6 years between individuals. The variations in the onset of puberty have also been associated with risk for hormone dependant cancer, diabetes, cardiovascular disease, and obesity. People with certain genetic types are at a higher risk of reaching puberty early.

Menopausal hormone therapy is widely prescribed for postmenopausal women to alleviate symptoms of menopause like hot flashes, vaginal dryness, and sleep disturbances. This therapy involves the administration of estrogen in the form of pills, patches, or topical creams. However, it has been associated with an increased risk for cardiovascular disease and breast cancer. Some genes promote higher growth of estrogen receptors during menopausal hormone therapy. This increases the risk of ER-positive breast cancer. A study revealed two regions in the POMP gene showing an interaction with hormone therapy that increases the risk of breast cancer.