Carcinoma Of The Breast (Breast Cancer)
by: Wong Lai Teng
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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