Breast cancer is a woman with multiple men a rare malignant tumor. Its incidence around the world, there are significant differences between the United States and the Nordic high-prone areas, followed by Eastern and Southern Europe and South America, Asia, the incidence of the lowest. However, from the 20th century, 70 years, the formerly low-incidence areas of Asia, the incidence rate had an upward trend.
While the complexity of breast cancer etiology and pathogenesis has not yet really understand, but the etiology of a number of studies have shown that a number of related factors and the pathogenesis of breast cancer.
(1) Family history of breast cancer have a certain relevance. As early as in 1974, Anderson and others noticed the first-degree relatives of women suffering from breast cancer, the probability of occurrence of breast cancer compared with those without family history of high 2 – 3 times. If a relative risk of bilateral breast cancer in pre-menopausal, then the relative risk is as high as 9 times. Shanghai 1988-1989, a survey showed that women suffering from breast cancer, family history of breast cancer relative risk of 4.5, shows that family history is an important risk factor.
(2) Reproductive factors: the body due to breast cells to cyclical changes in hormone levels, as well as elevated levels of pregnancy hormones and the proliferation of physiological changes occur, and thus the incidence of breast cancer and age at menarche, menopause age, menstrual cycle, production times and availability of breast-feeding history, marital status, research shows that: unmarried, early age at menarche, late menopause, the menstrual cycle is short, less parity, breast-feeding women is not the risk of breast cancer, its occurrence is greater. On the contrary the less dangerous.
(3) The impact of sex hormones is also one of the causes of breast cancer. Studies have shown that less than 20-year-old female breast cancer is an extremely rare occurrence, but less than 30-year-old women are not the common disease. Starting from 35-year-old the incidence of breast cancer increased year by year, and this increase in the incidence of almost throughout a woman’s life. In the 45-50 years old, an increase of slightly towards flat, and later steep rise. Suits the endogenous estrogen intake will significantly increase the incidence of breast cancer, such as: oral estrogen-containing drugs, Fung emulsion of the estrogen hormone through skin absorption, and oral contraceptives.
(4) Diet, fat, high-calorie diet, alcohol consumption have an increased risk of breast cancer.
(5) The past history of a benign breast tumor. Other factors include radiation, viruses, chemical irritants and certain diseases such as diabetes can also cause increased incidence of breast cancer.
