Breast cancer is the most common cancer in women. It is the most common cause of cancer-related death in women after lung cancer. Despite the variability in different populations, approximately one in every 8 women in western societies develop breast cancer during their lifetime. The incidence of breast cancer is constantly on the rise from past to present.
Sex: Being a woman is a risk factor in itself. The main reason for the increased incidence of breast cancer in women is that the breast tissue in women is constantly subjected to the effects of estrogen and progesterone; which induce tissue proliferation.
Age: It is a factor that increases the risk of breast cancer. The risk of breast cancer increases with advancing age.
Family history of breast cancer: Female relatives of women with breast cancer have a higher risk. Of breast cancer patients, mothers have a 2-fold and sisters have a 2.5-fold higher risk compared to the normal population.
• Genetic risk factors: In recent years, different genes have been isolated in association with familial breast cancer. Approximately 5 to 10% of breast cancers develop due to defective genes inherited from parents. The two genes that increase the risk of breast cancer are BRCA1 and BRCA2. The risk of developing breast cancer is 50-85% in women having one of these genes. It should not be forgotten that no hereditary factors are identified in 9 out of 10 patients with breast cancer.
Any presence of cancer in one of the breasts increases the risk of developing cancer in the other breast by 3-4 times.
Breast diseases with atypical hyperplasia (atypical ductal hyperplasia, atypical lobular hyperplasia) increase the risk of developing breast cancers. Diseases that do not cause excessive cell proliferation; including the fibrocystic disease, simple fibroadenoma, adenosis (non-sclerosing), benign phyllodes tumors, fat necrosis, mastitis, and ductal ectasia do not increase the breast cancer risk.
Stages in the female reproductive period: Early menarche is a risk factor for the development of breast cancer in late menopause. The longer the women are exposed to consecutive hormonal cycles throughout their lives, the more will be their likelihood to develop breast cancer.
Having no children or having the first baby after the age of thirty increases the risk of breast cancer slightly. Breastfeeding appears to have a protective effect because it reduces the number of menstrual periods during the lifespan of a woman.
Radiation Therapy: Radiotherapy to the chest area in childhood increases the risk of developing breast cancer.
Birth control pills and postmenopausal hormone therapy: The role of contraceptives in breast cancer development is controversial. Studies demonstrate that oral contraceptives slightly increase breast cancer risk. This risk starts diminishing after discontinuing the medications and, in ten years; it becomes equal to the risk in women, who have not used these medications. It is stressed that this risk is less with low-dose estrogen preparations.
Studies have shown that long-term hormone therapy in the postmenopausal period increases the risk of cancer and that there are no risks with short-term use. It should be remembered that these therapies significantly prevent osteoporosis and cardiovascular diseases although they increase the risk of breast cancer. If hormone therapy is decided to be started after menopause, the most appropriate mode of treatment will be a short-term one with the lowest possible doses.
Furthermore; alcohol consumption, low physical activity, and being overweight increase the risk of breast cancer.