Breast cancer – causes, frequency, epidemiology
Breast cancer is the most common female cancer. Nearly 40,000 new cases of this cancer are diagnosed in the UK each year, and 143,000 in the United States. Over the past 50 years, the incidence of breast cancer has gradually increased, with significant differences in geographic distribution. In developed countries of the West, this cancer is more common than in developing countries.
The figure below shows the incidence of breast cancer depending on age. On average, one in ten women develop breast cancer during their lifetime, which makes this disease the main cause of cancer death among women in the West. This type of cancer is so common in the UK that about half of all cancer patients have breast cancer.
There are a number of etiological factors predisposing to the development of breast cancer. Thus, the risk of the disease is three times higher in women whose immediate relatives suffered from this cancer. A particularly high degree of risk was noted for the daughters of those women who had breast cancer diagnosed during the premenopause period. For them, the probability of the disease increases by 3-11 times. Women who first gave birth to a child over the age of 30 years are almost three times more likely to develop breast cancer than women who have given birth before the age of 20 years.
The degree of risk also increases for those women who have benign breast diseases, especially such as epitheliosis and cell atypia, in a history. Tumors develop more often with early onset of menstruation and late menopause, and the removal of the ovaries, carried out in the early period of life, has some protective effect. It is known that prophylactic removal of the ovaries in women with mutations in the BRCA1 and BRCA2 genes significantly reduces the risk of developing breast cancer. Currently, a genetic analysis of mutations in women at high risk is carried out, that is, from families with hereditary breast or ovarian cancer.