common during the first few months of
taking the pill and is caused by incom-
plete suppression of the endometrium.
(See also vaginal bleeding.)
breastEither 1 of the 2 mammary glands,
which, in women, provide milk to nour-
ish a baby and are secondary sexual
characteristics. In males, the breast is an
immature version of the female breast.
At puberty, a girl’s breasts begin to
develop: the areola (the circular area of
pigmented skin around the nipple) swells
and the nipple enlarges. This is followed
by an increase in glandular tissue and
fat. The adult female breast consists of
15–20 lobes of milk-secreting glands
embedded in fatty tissue. The ducts of
these glands have their outlet in the
nipple. Bands of fine ligaments deter-
mine the breast’s height and shape. The
areolar skin contains sweat glands, seb-
aceous glands, and hair follicles.
The size and shape
and general appear-
ance of the breasts
may vary during the
menstrual cycle, dur-
ing pregnancy and
lactation, and after
the menopause.
During pregnancy,
oestrogenand pro-
gesterone, secreted by
the ovary and pla-
centa, cause the milk-
producing glands to
develop and become
active and the nip-
ple to become larger.
Just before and after
childbirth, the glands in the breast pro-
duce a watery fluid known as colostrum.
This fluid is replaced by milk a few days
later. Milk production and its release is
stimulated by the hormone prolactin.
breast abscessA collection of pus in
the mammary gland, usually in a
woman who is lactating (producing milk).
Breast abscesses develop if acute masti-
tisis not treated promptly. They occur
most commonly during the first month
after a woman’s first delivery. The initial
symptoms are of acute mastitis. The
abscess develops in one area, which be-
comes very firm, red, and extremelypainful. The treatment usually includes
antibiotic drugsand repeated aspiration
of the pus with a needle and syringe.
Rarely, surgical drainage may be needed.
breastboneThe common name for the
sternum, the front part of the thorax.
breast cancerA cancerous tumour of
the breast. The incidence is raised in
women whose menstrual periods began
at an early age and whose menopause
was late; in those who had no children
or had their first child later in life; in
those with mothers or sisters who had
breast cancer; and in those who are
obese. The disease is also more com-
mon in countries in which the typical
diet contains a lot of fat. One form of
breast cancer has a genetic component;
2 genes called BRAC1 and BRAC2 have
been identified and appear to be
involved in this type of breast cancer.
The first sign of breast cancer may be a
painless lump. Other symptoms may in-
clude a dark discharge from the nipple,
retraction (indentation) of the nipple, and
an area of dimpled, creased skin over the
lump. In 90 per cent of the cases, only 1
breast is affected. The cancer may be sus-
pected after discovering a lump during
breast self-examinationor mammography.
If a lump is detected, cells will be col-
lected from it by needle aspirationor
surgical biopsy. If the lump is cancerous,
the treatment given depends on the
woman’s age, the size of the tumour,
whether or not there are signs of spread
to the lymph nodes, and the sensitivity
of the tumour cells to hormones, as
assessed in the laboratory. A small
tumour, with no evidence of having
spread outside the breast, is removed
surgically. Lymph nodes in the armpit
are also commonly removed at the same
time. Surgery may be combined with
radiotherapyand/or anticancer drugs.
Secondary tumours in other parts of
the body are treated with anticancer
drugs and hormones. Regular check-ups
are required to detect recurrence or
the development of a new cancer in the
other breast. If the cancer recurs, it can
be controlled, in some cases, for years
by drugs and/or radiotherapy.
breast cyst A fluid-filled lump that forms
within the milk-producing tissue of theBREAST BREAST CYSTB
MuscleFatty tissueNippleAreolaMilk-secreting
glandBREASTMilk
duct