While the risk of developing breast cancer in a woman of a certain age who has no family members with breast cancer is 6%, the risk of developing breast cancer in women with a relative who has had breast cancer is 11%.

Another group, hereditary breast cancer, is the result of a defect in the genes. In families with hereditary breast cancer, the probability of children developing breast cancer is as high as 50% and there are many cases of breast cancer in the family.

Hereditary Breast Cancer is Associated with BRCA1 and BRCA2 Genes

BRCA1 and BRCA2 are two genes involved in repairing damage to cell DNA. If a mutation in the BRCA1 and BRCA2 genes develops, the risk of developing breast cancer increases because DNA repair is not possible.

Damaged genes are passed down through generations from parents to children. The risk of developing breast cancer in family members who carry this damaged gene reaches very high rates of 85-90%.

The lifetime risk of developing breast cancer in women with mutations in these genes is 87%. In 70% of women in this group, breast cancer occurs before the age of 45.

More than one first-degree relative (mother, sister or daughter) of the woman has breast cancer. This type of breast cancer usually (65%) develops in both breasts.

A woman or man who carries the damaged BRCA1 gene passes on the damaged gene to 2 out of 4 children. The fact that more than one family member develops breast cancer, that individuals with breast cancer are young, and that individuals develop cancer in both breasts draws attention to the possibility of genetic transmission.

These family members should be investigated for damage to the BRCA1 and BRCA2 genes. If people carry these damaged genes, risk-reducing measures should be considered.

Managing the Risks of BRCA1 or BRCA2 Gene Carriers Medication Prevention

Tamoxifen is used after breast cancer treatment to prevent the cancer from coming back in the other breast or elsewhere in the body. The use of tamoxifen to reduce the risk of developing breast cancer in BRCA1 gene carriers provides a significant protective effect. The protective effect of tamoxifen applies to breast cancer types that carry estrogen (ER) and progesterone (PR) receptors. Breast cancers that occur in carriers of the damaged BRCA1 gene are mostly ER and PR negative patients (i.e. they do not carry these receptors), so tamoxifen use is not effective enough.

Cancers that develop in carriers of the damaged BRCA2 gene are mostly ER and PR positive. In carriers of the damaged BRCA2 gene, tamoxifen reduces the risk of developing breast cancer and is recommended.

Surgical Prevention of Hereditary Breast Cancer

Reducing the risk of developing cancer by removing both breasts in women who carry mutated BRCA1 and BRCA2 genes can also be considered as a preventive treatment. The external appearance and aesthetics of the breast can be preserved by removing the breast tissue from the inside and applying prosthesis while preserving the external appearance of the breast completely. Since not all of the breast tissue can be removed in this type of intervention, breast cancer can be seen in 10% of these women.

Another surgical method is to remove the entire breast together with the skin tissue. When the entire breast is removed, the risk of cancer development is considerably reduced, but not completely eliminated. During this surgery, it is possible to create breast tissue and aesthetics with oncoplastic surgery methods.

Since the risk of ovarian cancer is also high (50%) in carriers of damaged BRCA1, removal of the ovaries is also recommended.Hereditary Breast Cancer is Associated with Brca1 and
Brca2 Genes