A cancerous growth that originates in the breast
- Risk increases with age
- In some cases, due to an abnormal gene
- Obesity, smoking, and delaying or avoiding pregnancy are risk factors
Breast cancer is the most common cancer in the UK, with about 46,000 women being diagnosed with the disease each year. It can also occur in men, although it is rare, with about 300 cases being diagnosed in the UK each year.
The risk of breast cancer is negligible under the age of 30 and then increases with age, doubling every 10 years; 8 out of 10 cases are diagnosed in women over the age of 50. The number of cases diagnosed each year in Europe and North America is increasing slightly. However, there has been a drop in the number of deaths from breast cancer in recent years, and now about 8 in 10 women with the disease survive for at least 5 years after diagnosis. The improved survival rate is due to better treatment and the increased use of mammography to screen for breast cancer, which means that tumours can be detected early, when they often respond well to treatment. Early treatment also reduces the likelihood of the cancer spreading to other parts of the body, such as the bones, spine, lungs, or liver. Screening reduces the number of breast cancer deaths in women over the age of 50 by about 4 in 10, saving about 1,400 lives a year in the UK. Women aged 50–70 are offered a mammogram every 3 years in the UK.
What are the causes?
The underlying cause of most breast cancers is unclear. However, some risk factors have been identified, many of which suggest that the female hormone oestrogen is an important factor in the development of the disease. Many cancerous breast tumours are oestrogen-sensitive, and oestrogen encourages them to grow once they have formed. Women who have their first period before the age of 11 or who have a late menopause seem to be at increased risk of developing breast cancer, probably because their breasts are exposed to oestrogen for longer. Similarly, the number of menstrual cycles before a first pregnancy has some influence on the risk of breast cancer; for example, a woman who never has children is about twice as likely to develop breast cancer as a woman who has her first child before the age of 20. Breast-feeding has an additional protective effect.
Obesity increases the risk of breast cancer because excess body fat causes an increase in oestrogen levels. Artificial oestrogen in some medications may also influence susceptibility to breast cancer. Combined oral contraceptive pills slightly increase the risk of developing breast cancer. Hormone replacement therapy in postmenopausal women is associated with a significant increase in risk, especially if continued for more than 10 years.
About 1 in 20 cases of breast cancer is linked to an abnormal gene, and several of these genes have now been identified (notably the BRCA1, BRCA2, and TP53 genes). Breast cancer with a genetic basis most commonly affects younger women, even as young as the late 20s, and may also affect men. If you have a close relative who had breast cancer before the age of 40, you may carry an abnormal gene and may be referred for genetic testing. The risk of developing breast cancer increases the more members of your family have had breast or ovarian cancer before age 40 (if close relatives have had breast cancer after age 40, the risk is only slightly increased). However, often, there is no family history of the disease. Noncancerous breast lumps do not increase the risk of breast cancer.
What are the symptoms?
It is very unusual for breast cancer to produce symptoms in its early stages. When symptoms do occur, they usually affect only one breast and may include:
A lump in the breast, which is usually painless and may be situated deep in the breast or just under the skin.
Dimpling of the skin in the area of the lump, or swelling of the skin with an “orange peel” appearance.
Inversion of the nipple.
A bloodstained nipple discharge.
In Paget’s disease of the breast, a rare form of breast cancer that originates in the milk ducts, the only symptom may be a patch of dry, flaky skin on the nipple, although there is also soreness and bleeding from the nipple (see Abnormal nipples).
Although these symptoms may result from noncancerous conditions, you should consult your doctor if you notice a change in your breasts. If breast cancer is not treated early, it can spread to the lymph nodes in the armpit and then to other organs, such as the lungs, liver, or bones.
How is it diagnosed?
You should become familiar with your breasts so that you can recognize any abnormal changes (see Breast awareness). Screening using mammography enables tumours to be detected before symptoms have appeared. Although this procedure is reliable, it may not detect every case and it is therefore important that you remain breast-aware even after a normal mammogram.
If you visit your doctor because you have noticed a lump or other abnormality of your breast, he or she will carry out a breast examination and check for signs of spread to the lymph nodes in the armpit. If your doctor finds a lump or other sign that might indicate breast cancer, he or she will refer you to a breast clinic. At the clinic you will usually undergo triple assessment: a physical examination by a specialist; breast imaging by ultrasound scanning and/or mammography; and a fine-needle aspiration and/or core biopsy. In a fine-needle aspiration, a sample of cells is taken from the lump; in a core biopsy, a sample of tissue is taken. The cells or tissue are then examined microscopically for the presence of cancer.
If the diagnosis of cancer is confirmed, further tests may be performed to find out whether the cancer is sensitive to oestrogen and if it has spread. A chest X-ray and liver ultrasound scan, or a CT scan may be arranged to look for evidence of spread to the lungs and/or liver, and a bone scan (see Radionuclide scanning) may be carried out to see if the bones have been affected. An MRI scan of the breasts may also be performed to accurately assess the extent of the cancer in the breast, especially in young women whose breasts are too dense for adequate mammographic assessment.
What is the treatment?
The extent of the cancerous growth within the breast, whether it has spread to other parts of the body, and whether it is oestrogen-sensitive are the main considerations when deciding on the most appropriate course of treatment. Once a full assessment has been made, your doctor will discuss your treatment options with you. Treatment of breast cancer may include surgery, radiotherapy, chemotherapy, hormone therapy, or, most frequently, a combination of these. Counselling may help you to come to terms with cancer, and some complementary therapies can be used to promote a sense of well-being. While you are undergoing treatment, you will be allocated a key person (often a breast-care nurse) who will be your main contact with the medical team looking after you.
Surgery is normally the first stage of breast cancer treatment. There are many possible types of operation used to treat breast cancer (see Surgery for breast cancer).
If the tumour is small, a lumpectomy (also known as a wide local excision) may be carried out, in which the tumour and about 1 cm (
In some cases, all of the tissue from the affected breast is surgically removed in a procedure known as a mastectomy. Some women choose to have a mastectomy because they think that this is the only way to make sure all of the tumour has been removed but medical studies have shown that this operation is not necessary for treating most single, small breast tumours.
For some breast cancers, a type of chemotherapy called neo-adjuvant chemotherapy may be given before surgery. The main benefit of this treatment is to shrink the tumour so that it becomes small enough for breast-conserving surgery rather than requiring a mastectomy. However, not all tumours are suitable for this type of chemotherapy.
During surgery, a number of lymph nodes from the armpit on the same side as the affected breast will be removed and examined to look for signs of cancer. If the lymph nodes are found to be free of cancerous cells, the cancer is unlikely to have spread from the tumour site and it will not be necessary to remove further lymph nodes. If the nodes do show signs of cancer, this indicates that the cancer has spread and the remaining lymph nodes will need to be removed, a procedure called axillary node clearance.
Surgery will affect the appearance of your breast. If one breast looks smaller after surgery, you may want to have the other breast reduced to the same size (see Breast reduction). After a mastectomy, many women have a breast reconstruction. This operation can either be performed at the same time as the mastectomy or at a later date.
Treatment with radiotherapy is given to almost all women after lumpectomy, regardless of the size of the tumour. It may also be used after a mastectomy if the removed tumour was growing close to the underlying muscle or the skin, or if the cancer is a fast-growing type or has spread to more than 1 or 2 lymph nodes. Treatment usually begins 1 or 2 months after surgery and is given 5 days a week for a period of 4–6 weeks. The aim is to destroy any cancer cells that may remain after surgery.
Tumours that are oestrogen-sensitive usually respond to drugs that block the action of oestrogen (endocrine therapy), whereas cytotoxic chemotherapy can be effective for many other types of tumour. Treatment with synthetic forms of substances made naturally in the body called monoclonal antibodies (biological therapy) can be useful in the treatment of breast cancer in which the cancer cells are of a particular type. Often a combination of drug therapies is used.
Endocrine therapy inhibits the effects of oestrogen, with the result that oestrogen-sensitive tumours shrink or do not grow as quickly. Tamoxifen (see Sex hormones and related drugs) is an oestrogen-inhibitor that is used mainly to treat breast cancer in premenopausal women, although it may also be used in some postmenopausal women; it is also effective in preventing breast cancer in women at increased risk. It is usually taken for 5 years. Drugs known as aromatase inhibitors (such as anastrozole) also inhibit oestrogen production but are effective only in postmenopausal women.
Cytotoxic chemotherapy involves using combinations of drugs that destroy rapidly dividing cancerous cells. Treatment is usually given at intervals of 3–4 weeks over a period of 4–6 months. In most cases, cytotoxic chemotherapy is used in addition to surgery. These drugs can also kill normal cells, and commonly cause side effects such as hair loss and mouth ulcers.
Biological therapy is a form of chemotherapy that uses synthetic monoclonal antibodies (such as Herceptin) to boost the body’s immune response to cancer cells. It is given for at least a year and generally has fewer side effects than other chemotherapy drugs. However, it is only effective against specific types of cancer cells, and it is not suitable for women who have certain heart or circulatory problems.
Women with breast cancer may choose to complement conventional treatments with other therapies, such as relaxation exercises, meditation, homeopathy, or acupuncture. These therapies should not be regarded as alternatives to conventional treatment. If you are considering using complementary therapies, you should consult your doctor. Counselling, in which people are encouraged to express their feelings, may also be helpful in coping with cancer.
What is the prognosis?
If breast cancer is diagnosed before it has spread to other organs, treatment is very likely to be successful. Combinations of treatments usually give the best results, and the success rate of treatment has improved dramatically in recent years.
Following treatment, you will have follow-up examinations at the hospital and annual mammograms to check for a recurrence of the disease. About 1 in 4 women treated for breast cancer has a recurrence within 5 years, usually those who had advanced cancer when they were first diagnosed. Cancer may recur close to the site of the original tumour or in a different area, and any recurrence requires further treatment.
About 8 in 10 women who receive treatment for breast cancer survive for more than 5 years after the disease is diagnosed.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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