About 12 percent of women in the general population will develop breast cancer sometime during their lives. By contrast, 55 to 65 percent of women who inherit a harmful BRCA1 mutation and around 45 percent of women who inherit a harmful BRCA2 mutation will develop breast cancer by age 70 years.
About 1.3 percent of women in the general population will develop ovarian cancer, but 39 percent of women who inherit a harmful BRCA1 mutation and 11 to 17 percent of women who inherit a harmful BRCA2 mutation will develop ovarian cancer by age 70 years.
In addition to ovarian and breast cancer, harmful mutations in BRCA1 and BRCA2 increase the risk of several cancers. BRCA1 mutations may increase a woman’s risk of developing fallopian tube cancer and peritoneal cancer. Men with BRCA2 mutations, and to a lesser extent BRCA1 mutations, are also at increased risk of breast cancer and have a higher risk of prostate cancer. Men and women with BRCA1 or BRCA2 mutations may also be at increased risk of pancreatic cancers .If mutations are inherited from both parents, childhood solid tumors and development of acute myeloid leukemia may occur.
A positive test result indicates that a person has inherited a known harmful mutation in BRCA1 or BRCA2 and, therefore, has an increased risk of developing certain cancers. However, a positive test result cannot tell whether or when an individual will actually develop cancer. For example, some women who inherit a harmful BRCA1 or BRCA2 mutation will never develop breast or ovarian cancer.
A positive genetic test result may also have important health and social implications for family members, including future generations. Unlike most other medical tests, genetic test scan reveal information not only about the person being tested but also about that person’s relatives. Both men and women, who inherit a harmful BRCA1 or BRCA2 mutation, whether or not they develop cancer themselves, may pass the mutation on to their sons and daughters. Each child has a 50 percent chance of inheriting a parent’s mutation. If a person learns that he or she has inherited a harmful BRCA1 or BRCA2 mutation, this will mean that each of his or her full siblings has a 50 percent chance of having inherited the mutation as well.
Several options are available for managing cancer risk in individuals who have a known harmful BRCA1 or BRCA2 mutation. These include enhanced screening, prophylactic (risk-reducing) surgery, and chemoprevention
People with BRCA1 and BRCA2 mutations are recommended to start cancer screening at younger ages. Women with BRCA2 mutation undergo clinical breast examinations beginning at age 25 to 35 years and have a mammogram every year, beginning at age 25 to 35 years. Recent studies have shown that MRI may be more sensitive than mammography for women at high risk of breast cancer.
Some groups recommend transvaginal ultrasound, blood tests for the antigen CA-125, and clinical examinations for ovarian cancer screening in women with harmful BRCA1 or BRCA2 mutations.
Prophylactic surgery involves removing as much of the “at-risk” tissue as possible. Women may choose to have both breasts removed (bilateral prophylactic mastectomy) to reduce their risk of breast cancer. Surgery to remove a woman’s ovaries and fallopian tubes (bilateral prophylactic salpingo-oophorectomy) can help reduce her risk of ovarian cancer.
Prophylactic surgery does not guarantee non development of cancer. Women have developed breast cancer, ovarian cancer, or primary peritoneal carcinomatosis (a type of cancer similar to ovarian cancer) even after prophylactic surgery.
Chemoprevention is the use of drugs, vitamins, or other agents to try to reduce the risk of, or delay the recurrence of, cancer. Two chemopreventive drugs (tamoxifen and raloxifene) have been approved.
Having said this BRCA I & BRCA II testing should only be done after genetic counseling .An assessment should be made only after properly assessing the family medical history and personal medical history.
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