Breast cancer is the most common cancer in women worldwide. It is estimated that over one million cases are diagnosed each year. In the USA it is estimated that in 2006, some 213,000 new cases will be diagnosed, of which 41,000, or one in five women, will die of the disease. The worldwide incidence is rising but the mortality (death) rate is falling, in part due to earlier diagnosis with mammograms and better treatment with newer and more powerful drugs.

The cause of breast cancer remains unknown. It is rare under the age of 30, but the incidence increases with age and is more common after the age of 50. The average age of diagnosis is around 58. {{more}}

It is more common in the more developed countries as compared to the less developed countries. Caucasians are more susceptible than other ethnic groups. There is a marked geographical variation in the incidence and mortality of breast cancer between countries. For example the incidence is higher in the UK, USA and Europe than elsewhere. The mortality (death) in the UK is worse than in Europe. Immigrants from a country with a low incidence of breast cancer to one of higher incidence experience an increase in incidence to levels just below that of their adopted country within three generations.

The level of fat consumption has been implicated as contributing to this phenomenon.



Risk factors



Anything that increases a person’s chance of getting a disease is called a risk factor, for example smoking increases the risk of getting lung cancer. In breast cancer a number of risk factors are involved, however even though one may have one or more of these risk factors, it does not mean one will get the disease. The following are some of the identifiable risk factors:

Female;

Age above 50;

Country of birth; North America, North Europe;

Previous history of breast cancer;

Family history of breast cancer (first degree relatives such as mother, sister, daughter);

Genetics: carriers of alterations in the BRCA1 or BRCA2 breast cancer genes;

Early onset of menstruation or late menopause (more menstrual cycles);

Old age at first birth or never having given birth;

Previous treatment with radiotherapy to the chest or breast;

Postmenopausal obesity;

Use of hormone replacement therapy (post menopausal);

Previous breast biopsy with atypical proliferative hyperplasia (precancerous or cancerous cells); or

Moderate alcohol intake.

More than 70 per cent of women over the age of 50 who get breast cancer have no other identifiable risk factors other than female and age.

Breast cancer may present with one of the following features:

A palpable (discernible) lump in the breast;

A change in the size or shape of the breast;

Dimpling or puckering in the skin of the breast;

An unusual thickening or nodularity;

A rash around the nipple;

A blood stained nipple discharge; or

A feeling of discomfort in an area of the breast.

Pain is not a feature of breast cancer and more than 95 per cent of women with breast pain have no features to indicate breast cancer.



Tests

A number of diagnostic tests are then done to detect and verify the diagnosis of breast cancer. These include:

Mammogram: this is an x-ray of the breast which picks up features suggestive of cancer. It is 85-90 per cent accurate. There are some lumps which can be felt but do not show up on a mammogram, requiring further assessment. Mammography is the tool used in screening asymptomatic women and has the ability to detect cancer at an early stage. Various screening protocols are used, some countries such as the USA start screening at age 40 and do annual mammograms while the UK starts at age 50 and does mammograms every two years.

Ultrasound: this is a complementary tool to mammography and is useful for differentiating cysts and solid lesions. Some lesions not seen on mammogram can often be seen on ultrasound. Ultrasound is not useful as a screening tool. It is useful in younger patients under the age of 35 who tend to have denser breast tissue which may cause difficulties in assessment of mammograms;

Biopsy: once a lesion has been identified tissue needs to be obtained and examined by a pathologist under the microscope looking for signs of cancer. A number of biopsy methods can be performed:

Needle biopsy: using a thin needle and syringe, tissue is removed for analysis;

Core biopsy: using a special wide needle and a biopsy gun, a core of tissue is removed for analysis. This is more accurate than a needle biopsy;

Incisional biopsy: under a local anaesthetic, a portion of the lesion is removed;

Excision biopsy: all of the lesion or suspicious tissue is removed and analysed;

Estrogen and Progesterone receptor test: this measures the amount of estrogen and progesterone hormone receptors present in can-cer tissue. If positive, then endocrine therapy can be used as part of the treatment plan to stop the tumour from growing or spreading;

Her2neu test: this measures the presence of a growth factor receptor on breast cancer cells, which when stimulated will cause the tumour to grow rapidly. A new drug, Herceptin, is now available to block the Her2neu receptors.



Once the appropriate tests are done and the diagnosis is confirmed, the disease is staged. That is there is a determination of whether the cancer is confined to the breast or has spread to lymph glands or other areas such as the lungs or the bones. Staging along with other information affects the prognosis (chances of recovery) and guides treatment options.



Treatment involves one or all of the following:

Surgery: the removal of the affected part of the breast and axillary lymph glands – breast conservation surgery;

Removal of the whole breast and axillary lymph glands –

mastectomy;

Radiotherapy: uses high energy x-rays and other types of radiation to kill cancer cells;

These forms of treatment control the cancer locally in the breast region;

Chemotherapy: uses powerful drugs to stop cancer cells from growing by killing them or stopping them from dividing;

Endocrine (hormonal) therapy uses drugs to block the action of hormones, thereby killing or stopping the growth of cancer cells. Breast cancer cells with places for hormones to attach (receptors) can be blocked and eliminate the effect of estrogen and progesterone on them. Tamoxifen is an example of hormonal therapy and is given for five years;

Biological therapy: uses the body’s immune system to destroy the cancer cells;

These modalities control or destroy cancer cells in all parts of the body.

In addition to staging and the results of tests on the cancer cells, a patient’s age (pre or post menopausal) and general well being are also assessed and used to determine the course of treatment. The patient’s feelings regarding treatment options must also be taken into consideration before a final decision is made.