Saturday, June 8, 2013

Breast Cancer causes

Currently, there are more than 180,000 new cases of breast cancer every year in the United States and 46,000 deaths, and it has been estimated that one of every eight American women living to age 95 years will develop breast carcinoma. Until 1983, breast cancer was the leading cause of cancer deaths among females; despite an increase in the incidence of breast carcinoma, it is now second to lung cancer because of the larger increase in the number of women developing lung cancer.

Breast carcinoma is rare before 25 years of age and uncommon before 30 years; the incidence increases sharply after 40 years, with a mean and median age of 60 years. Statistically, the risk of breast cancer is increased in nulliparous women (nuns have a high incidence), in women who have early menarche and the late menopause, and in those who have their first pregnancy after age 30. Breast feeding appears to have protective effect for the mother. Evidence linking oral contraceptives to breast cancer is scant; a few studies suggest a very slightly increased incidence in women who use oral contraceptives.

A familial history (limited to first-degree relatives, i.e. mother, sister, daughter) of breast carcinoma increases the risk fivefold. The first-degree relatives of woman who develops bilateral breast cancer before menopause are at greatly increased risk. The increased risks resulting from atypical hyperplasia and family history are additive.

The etiology of breast carcinoma is unknown but is probably multifactorial. Genetic factors are suggested by the strong familial tendency. There is no inheritance pattern, suggested that the familial incidence is due either to the action of multiple genes or to similar environmental factors acting on members of the same family. Mutation of the BRCA-1 and BRCA-2 is believed to cause breast cancer. Hormones are also widely believed to play a role in the etiology of breast cancer. Estrogen has been the most extensively studied hormone because of the epidemiological evidence that prolonged estrogen exposure (early menarche, late menopause, nulliparity, and delayed pregnancy) increases the risk of breast cancer. Viruses are also suspected of causing breast cancer (e.g., the Bittner milk factor is a virus that causes breast carcinoma in mice).

Carcinoma of the male breast is extremely rare. It presents with a painless breast mass. Histological features are identical to those of infiltrating ductal carcinomas in the female. In spite of the small bulk of the breast in men, the diagnosis of male breast carcinoma is usually delayed; 50% of patients have axillary lymph node metastases at the time of diagnosis. As a result, male breast cancer has a worse overall prognosis than female breast cancer.
Nulliparous — a woman who has never borne a viable child. 
Hyperplasia — abnormal increase in the number of normal cells in normal arrangement in an organ or tissue, which increases in volume.


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