What is breast cancer?
The breast is a gland that consists of breast tissue supported by connective tissue (flesh) surrounded by fat. The easiest way to understand how the inside of the breast is formed is by comparing it to an upturned bush. Its leaves are known as lobules and they produce milk that drains into ducts that are the branches of the breast tree. These in turn drain into 12 or 15 major or large ducts which empty onto the surface of the nipple, just like the branches of a tree drain to the trunk.
Breast cancer develops from the cells that line the breast,
lobules and the draining ducts. Cancer cells that remain confined to the lobule
and the ducts are called '
How common is breast cancer?
Breast cancer is the most prevalent cancer among women and
affects approximately one million women worldwide. Breast cancer accounts for
18 per cent of all female cancers and approximately 1 in 10 women in the UK
will get breast cancer sometime during their life.
What are the risk factors leading to the development of breast
cancer?
Geographical variation
However, studies of women from Japan who emigrate to the US
show that their rates of breast cancer rise to become similar to US rates
within just one or two generations, indicating that factors relating to
everyday activities are more important than inherited factors in breast
cancer.
Reproductive factors
Age at first pregnancy
Inherited risk
Previous breast disease
Radiation
Other studies have shown that women with
Hodgkin's disease who
received radiation therapy to the chest have an excess risk of breast cancer.
As they are surviving to older age they are now developing not only unilateral
but bilateral breast cancer. The increase in risk depends on the dose and the
age at which they received radiation. Data has also suggested that there is
increased risk of contralateral breast cancer in patients having radiation to
one breast.
Lifestyle
Weight
Alcohol intake
Hormones
Hormone replacement therapy
What are the symptoms of breast cancer?
Other signs of breast cancer include:
How is breast cancer diagnosed?
Mammograms
Ultrasound scanning
Needle tests
Having the lump removed
Before any operation, the patient will be asked to sign a
consent form agreeing to the removal of the lump. It is important for the
patient to know that the doctor performing the operation will only remove the
lump and will not take any more tissue away without explaining any further
procedure to the patient first and getting her consent.
What are the types of breast cancer?
A more logical classification divides tumours into those of
'special' and 'no special' type. Invasive carcinoma of no special type is also
commonly referred to as invasive ductal carcinoma. It is the most common type
and accounts for up to 85 per cent of all breast cancers.
Special types of tumour have particular microscopic features and
these include invasive lobular carcinoma, invasive tubular, cribriform,
medullary and mucinous cancers, with other types being uncommon. Many of the
special type cancers have a better prognosis - in other words the patient has a
higher chance of survival.
When a cancer is examined under the microscope, it is usually
possible to assess how aggressive it is: in other words how far and how fast it
is likely to spread. The tumour may be assigned to one of three grades ranging
from grade I to grade III in order of seriousness. For instance, a grade I
cancer is non-aggressive and unlikely to cause harm. In contrast, grade III
tumours are aggressive and likely to cause harm, but can sometimes be
controlled with effective treatment.
How is breast cancer treated?
A simple way of staging or classifying breast cancer is to
divide it into three groups.
Locally advanced breast cancer
Advanced breast cancer
Other tumours in the breast
How does breast cancer develop?
As with invasive disease, there are two main types - ductal
carcinoma
Under the microscope these look different and, clinically, these
two types of non-invasive cancer behave differently and require different
treatments. Certain types of DCIS produce characteristic microcalcifications
which give rise to a typical pattern on mammograms (breast X-rays).
DCIS is much more common than LCIS. DCIS accounts for over one
fifth of all types of cancer detected by breast screening.
DCIS is treated by surgery which may be followed by radiotherapy
and hormonal treatment. LCIS when diagnosed is usually treated by simple follow
up with regular mammograms or with hormonal tablets (tamoxifen).
Only rarely is surgery used for LCIS.
If untreated, DCIS cells eventually spread into the surrounding
connective tissue of the breast to form an invasive cancer. The time period in
which DCIS changes into an invasive cancer appears to be over months and years
rather than days or weeks.
When an invasive cancer has developed, it is at this stage that
there is a risk that cancer cells can spread to nearby lymph glands, the most
common lymph glands affected being in the axillary (armpit) region. Cancer
cells can also enter the blood stream through the blood vessels that supply the
cancer and then move to other organs of the body where they grow and cause
problems in these organs. The most common sites for breast cancer to spread to
are the bones, lungs, liver and brain. Sarcomas if they spread do so mainly
through the bloodstream.
Can breast cancer be prevented?
Screening, as currently practiced can reduce the mortality but
not the incidence of breast cancer (and then only in the age group that is
screened).
Once a woman reaches the age of 50, she will be invited to take
part in a breast screening programme. In the UK, this means having a
mammogram every three
years up to the age of 64. If you want to continue to be screened after the age
of 64 you will need to make an appointment by phoning the breast screening unit
or visiting the screening van when it is in your area. The aim of screening by
mammography is to pick up cancer while it is still small before it has a chance
to spread.
There are various reasons why women are not normally screened
below the age of 50:
How is breast cancer treated with surgery and
radiotherapy?
Local treatments consist of surgery and radiotherapy.
If the lump is relatively small it is usually possible for the
surgeon to remove it along with a small amount of surrounding normal tissue.
This is called lumpectomy, wide local excision or breast-conserving surgery.
With a larger lump, this breast-conserving operation may not be possible
because so much of the breast tissue would have been taken away that it would
badly distort the breast. Once the lump and surrounding tissue is removed it
needs to be examined under the microscope. In some women, the surrounding
tissue is abnormal and a further operation is necessary.
A mastectomy (removal of the whole breast) may be necessary
if:
As well as removing the lump or breast, the surgeon will also
usually remove some or all axillary lymph glands, which are found under the
arm. There are about 20 of these lymph glands and they are the most common
place for cancer to spread. Knowing whether this has happened and, if so, how
many glands are affected is important in both assessing the severity of the
cancer and deciding on follow up treatment. If the surgeon needs to check
whether the cancer has spread to these glands, then removing either a single
gland which drains the cancer or a few of these glands is all that is needed.
If however the surgeon wants to find out exactly how many lymph glands are
affected, then it is necessary to remove all 20 lymph nodes from the axilla.
If it has been decided to treat the patient by mastectomy, the
surgeon will probably discuss with her the possibility of having her breast
rebuilt at the same time. The results of breast rebuilding or reconstruction
are usually more successful if this is performed straight away rather than left
until many months or years later. There is no evidence that immediate
reconstruction makes any recurrence of the cancer more likely. If the cancer
does return, reconstruction does not make it harder to detect.
Radiotherapy
How to treat breast cancer with medicines
The medicines for treating breast cancer fall into two groups:
hormones and chemotherapy. Whether the patient receives hormone therapy or
chemotherapy will depend on the size of the tumour, type of tumour (including
the grade) and whether the tumour has spread to involve the lymph
glands.
Tumours can be classified into oestrogen sensitive and
insensitive tumours.
In premenopausal women who are still having regular menstrual
periods, about half of all breast cancers are hormone sensitive. Over two
thirds of tumours in postmenopausal women whose periods have stopped are
oestrogen sensitive.
The most commonly used medicine against oestrogen sensitive
tumours is
tamoxifen. This medicine is an
anti-oestrogen in its effect on breast cancers and works by stopping oestrogen
getting to the cancer cells. It appears to be a very safe medicine but can
cause side effects which can be distressing and these include flushing (similar
to those women experience during the menopause), vaginal dryness and vaginal
discharge. Many women complain of weight gain on tamoxifen, but, in randomised
studies, women taking tamoxifen put on a similar amount of weight to those
women who were not receiving drug treatment. There is an increased incidence of
eye problems and disturbance of vision. This is reversible if the medicine is
stopped. The most serious possible side effect of tamoxifen is that it can
slightly increase the incidence of cancer of the lining of the womb, but this
risk is very low. Tamoxifen has been widely used throughout the world and is a
very safe medicine for pre and postmenopausal women. Few women have to stop the
medicine because of side effects.
The production of oestrogen in postmenopausal women requires
an enzyme called aromatase. A new class of medicines for treating breast
cancers blocks this aromatase enzyme. These medicines are called aromatase
inhibitors and include
letrozole,
anastrozole and exemestane. They are
very effective in postmenopausal women. The side effects include flushings,
nausea and lack of appetite. Occasionally, women have to stop the medicine
because of the constant feeling of sickness.
In premenopausal women the major source of oestrogen is the
ovaries. Either removing the ovaries or using an injectable medicine which
stops the ovaries from producing oestrogen are effective treatments in hormone
sensitive breast cancer. The medicines which stop the ovaries working have to
be injected once a month. Side effects of these medicines or removal of the
ovaries include the rapid onset of menopausal symptoms.
Chemotherapy
Chemotherapy is sometimes administered prior to surgery in
order to shrink a tumour. As outlined above, this sometimes means that the
surgeon is able to perform less extensive surgery in patients whose cancers
shrink.
Cancer chemotherapy is usually given through an intravenous
drip in the hand or arm on an outpatient basis. Treatments vary but each
session usually lasts between one and two hours and is repeated every three
weeks. Patients may be frightened because they have heard about very unpleasant
side effects such as nausea, vomiting and hair loss. In fact, by no means
everyone will experience all or even any of these problems. Some of the
anti-cancer drugs which are in common use cause little or no hair thinning and
anti-sickness medicine given with the chemotherapy works well.
A common complaint in people receiving chemotherapy is of
weight gain. This is due to the
anti-sickness pills which are taken
after the chemotherapy. Once the chemotherapy is finished, providing the
patient remains active, they should return to their initial weight. One of the
less well-known side effects of chemotherapy is to cause premature menopause.
This means that periods are likely to stop at a much earlier age if you have
had this type of treatment. Bringing forward the menopause is particularly
likely to occur in women in their late 30s and 40s, but even younger women can
find that their periods temporarily stop during chemotherapy.
Treatment for locally advanced breast cancer
Drug therapy can consist of either hormonal therapy in slower
growing hormone sensitive cancers or chemotherapy in hormone sensitive or more
rapidly growing cancers.
Outlook for patients with operable or early breast cancer
These include:
Outlook for patients with locally advanced breast
cancer
Outlook for patients with metastatic breast cancer
There is quite a difference in incidence and death rate of
breast cancer between different countries. The biggest difference is between
Eastern and Western countries. Recent, age-adjusted figures show that the rate
of breast cancer per 100,000 women is 24.3 in Japan and 26.5 in China compared
to 68.8 in England and Wales and 72.7 in Scotland and 90.7 in North America in
white females.
Women who start menstruating early in life or who have a late
menopause have an increased risk of breast cancer. Women who have natural
menopause after the age of 55 are twice as likely to develop breast cancer as
women who experience the menopause before the age of 45.
Having no children and being older at the time of the first
birth both increase the lifetime incidence of breast cancer. The risk of breast
cancer in women who have their first child after the age of 30 is about twice
that of women having their first child before the age of 20. The highest risk
group are those who have their first child after the age of 35 and these women
have an even higher risk than women who have no children.
Up to 10 per cent of breast cancer in Western countries is due
to an inherited factor. This factor can be passed on from either parent and
some family members pass on the abnormal gene without developing cancer
themselves. It is not yet known how many breast cancer genes there are, but to
date, two specific breast cancer genes have been identified.
Women with certain benign changes in their breasts are at
increased risk of breast cancer. These women present with a breast lump, have
an operation and the breast tissue removed shows severe overgrowth of the cells
lining the breast lobule.
Doubling of the risk of breast cancer was observed among
teenage girls exposed to radiation during the second world war. Another study
of women who received radiation to the chest as a result of repeated
X-rays for
tuberculosis, found
that there was a risk among women who were first X-rayed between the ages of 10
and 14 years. Fortunately, as TB itself has been prevented, this risk is less
relevant today.
Although there is a close correlation between the incidence of
breast cancer in a country and the dietary fat intake of that country, more
detailed studies have shown that there does not appear to be a particularly
strong or consistent relationship between fat intake in any individual and
their risk of developing breast cancer.
Being overweight is associated with a doubling of the risk of
breast cancer in postmenopausal women whereas amongst premenopausal women
obesity is associated
with reduced breast cancer incidence.
Some studies have shown a link between the amount of alcohol
people drink and the incidence of breast cancer, but this relationship is not
consistent and may be influenced by other dietary factors rather than alcohol.
Women who take the
oral contraceptive pill are at a
slight increased risk while they take the Pill and they remain at risk for 10
years after coming of the Pill. The increased risk is, however, very small and
cancers diagnosed in women taking the oral contraceptive Pill are less likely
to have spread than those cancers diagnosed in women who have never used the
oral contraceptive. The duration of use, age at first use, dose and type of
hormone within the contraceptive appears to have no significant effect on
breast cancer risk. Women who begin taking the Pill before the age of 20 appear
to have a higher risk than women who begin taking oral contraceptives at an
older age.
Among current users of
hormone replacement therapy(HRT) and
those who have stopped using it one to four years previously, there is an
increased risk of breast cancer. The risk increases 1.023 times for each year
of use. This increased risk is very similar to the effect of a delay in the
menopause by one year. The risk of breast cancer in a woman who has not used
HRT increases 1.028 times for each year she is older at the menopause. There is
no marked variation between different types of HRT or dose of HRT and breast
cancer risk. Cancers diagnosed in women taking HRT tend to be less advanced
clinically than those diagnosed in women who have not used HRT. Current
evidence suggests that HRT does not increase breast cancer mortality.
If a woman has any breast symptoms it is very important that she
consult her doctor so that the cause of these symptoms can be found. If breast
cancer is found at an early stage this improves the chances of recovery. As a
rule, the doctor will ask her a number of questions.
If the patient is over 35 and has not had a breast
X-ray within the past
year, the doctor may arrange for one to be performed. Breast X-rays are known
as
mammograms.
Mammograms are a good way of identifying abnormalities in the breast, but they
don't always tell whether they are benign or malignant. Further tests are
sometimes necessary and these tests include ultrasound and fine needle
aspiration cytology.
X-rays do not pass easily through the breasts of young women.
Ultrasound scanning,
which is familiar to many women by its use to look at babies during pregnancy,
can also be used in the breast to tell whether a lump is fluid or solid.
Ultrasound is not useful as a screening test. It is useful if an abnormal
shadow is seen on the mammogram because ultrasound is an accurate way of
judging whether any abnormality is benign and straightforward or whether it is
more likely to be serious.
Inserting a needle into the lump will show whether it is full
of fluid (a cyst) or solid. The needle can allow a sample of cells to be
removed for examination under the microscope and this is a very accurate method
of finding out whether the lump is benign or malignant. If there is an
abnormality on the mammogram, but no lump to feel, then using either the X-ray
machine or the ultrasound machine, it is possible to guide the needle into the
area of abnormality and to obtain enough cells or tissue to obtain a definite
diagnosis.
After investigation, the doctor may decide the lump is benign
and that it can be left alone. Alternatively the doctor may suggest that the
lump should be removed. This is called an excision
biopsy and it can be performed either
while the patient is awake under local anaesthesia or, more commonly, under a
general anaesthetic.
Breast cancer was originally described according to its
appearances, so words like scirrhous (meaning woody) were used and still appear
in the literature. More recently, breast cancer has been classified according
to its appearances when under the microscope. Early pathologists classified
breast cancers into 'invasive ductal' cancers and 'invasive lobular' cancers
believing that invasive ductal cancers arose in ducts and invasive lobular
cancers in the lobules. However, it is now clear that all invasive ductal and
invasive lobular cancers arise either in the terminal duct or the lobule. As
the terms invasive ductal and lobular are in such common usage and as they have
different appearances under the microscope they are still used.
The treatment of the disease depends on the tumour type and the
stage of disease - how far it has spread to involve either lymph glands or
other organs in the body. There are various ways a cancer can be staged and
classified.
This has not apparently spread beyond the breast and axillary
lymph glands but involves the skin or the chest wall of the breast. These
cancers tend to have a worse outlook than early breast cancer and are usually
best initially treated by drug therapy or radiotherapy rather than surgery. In
locally advanced breast cancer the skin of the breast can either be directly
involved by cancer or it is swollen or red. These changes occur because cancer
cells get into the fluid channels that drain the breast (lymphatics) and block
them, which causes the skin of the breast to be swollen and look like the skin
of an orange (peau d'orange). Locally advanced breast cancers were initially
treated with surgery but this treatment was successful in only about 30 per
cent of patients. In the remainder, the cancer recurred in the areas
immediately next to where the surgery was performed
This is where the cancer has spread beyond the breast and arm
pit to other parts or organs of the body such as lymph glands in the neck,
bone, lungs, liver and brain.
A rare form of tumour in the breast arises from the supporting
tissue and is called a sarcoma. These types of tumour are rare and account for
much less than 1 per cent of all malignant tumours within the breast. These are
usually best treated by surgery.
Initially, carcinoma cells are confined within the lobule and
adjacent ducts. These are known as non-invasive cancers or 'carcinoma
One particular medicine,
tamoxifen, has been shown in an
American study to reduce the risk of developing breast cancer by approximately
50 per cent.
Early breast cancer can be treated by a combination of local
treatments to control the local disease and systemic treatments to kill any
cells which may have spread.
Medicines act on cancer cells which have spread. We know that in
some women there are small numbers of cancer cells that have spread beyond the
breast but cannot be detected by scans. Medicines can kill these cells or
prevent them from growing for many months and years after surgery with or
without radiotherapy. In some patients with larger but operable breast cancers,
the medicines can be used before surgery to shrink the cancer. This allows some
women who would initially have required a mastectomy to be treated by less
extensive surgery. If the cancer has already spread at the time it is first
diagnosed or a patient who is treated for early breast cancer develops a
recurrence of the cancer at some other site in the body, then the only
practical way of treating these two groups of patients is by medicines.
Chemotherapy involves being given a
combination of anti-cancer medicines, often up to three at a time. The prime
target for such medicines is cancer cells that are actively growing and
dividing. Unfortunately, anticancer medicines are not able to recognise cancer
cells specifically and they kill normally dividing cells such as the blood and
hair cells. The art of the science behind successful cancer chemotherapy is
combining medicines which are chosen to minimise the damage to blood cells
while maximising damage to cancer cells.
Some patients whose cancer is locally advanced because it has
grown directly into the skin overlying the breast are suitable for surgery and
are treated in an identical way to patients with early or operable breast
cancer. The majority of patients with locally advanced breast cancer are
treated with drug therapy followed by surgery and/or radiotherapy. Some
patients with locally advanced breast cancer are treated by radiotherapy
initially which can be followed by drug therapy and/or surgery.
There are various factors which relate to survival in breast
cancer.
The outlook is worse than for patients who present with operable
breast cancer. Local recurrence of the disease after treatment is a problem
even in patients who have had drug treatment, surgery and radiotherapy. Control
rates of disease are however much better than they used to be when surgery was
the initial treatment. The outlook is better in patients who have a good
response to their initial drug treatment. In approximately 10 per cent of
patients who receive chemotherapy, the drug treatment is so effective than when
surgery is performed, no breast cancer cells can be identified in the breast or
the lymph glands.
Metastasis is the process of further spread of the cancer within
the body, away from the site at which the cancer starts. People whose cancers
have already spread have a much worse outlook than those whose disease is
apparently localised. There are differences in survival, depending on the site
affected.
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