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What is breast cancer?
Breast cancer is the most common cancer to affect women. It occurs most often in women over 50 years of age, but sometimes can also affect men, as men also have breast tissue that never fully develops. Breast cancer usually grows in the cells that produce milk and which line the milk ducts. These abnormal cells grow uncontrollably, and can spread beyond their natural boundaries. The cells can potentially spread to other sites within the body, such as the brain or liver.
Breast cancer is often diagnosed after finding a lump in the breast, although it can also be found by a screening test called a mammogram. Surgical intervention usually forms part of the treatment of breast cancer and it may be supplemented with radiotherapy, chemotherapy or hormonal treatments. Treatment of breast cancer has improved markedly over the past few decades, so most people will beat the disease.
The cause of breast cancer, as with other cancers, is damage to cellular DNA. This damage results in uncontrolled growth of these abnormal cells, which leads to formation of a tumour. Tumours can invade nearby tissue, or cancerous cells can separate from the tumour and spread throughout the body via the bloodstream or lymphatic system. The exact causes of this cellular damage in the breast are not known, but there are a number of proposed risk factors.
Risk factors for breast cancer include:
- Age - after 30 years of age the risk increases. The large majority of breast cancers occur in women over the age of 50;
- Family history - the majority of breast cancers are not hereditary, but family history does increase the risk for an individual, particularly if there are one or more close relatives (mother, sister) with breast cancer;
- Genetics - there are genes that are associated with a high risk of developing breast cancer. These genes include BRCA1, BRCA2 and P53. These are rare and only make up a small percentage of overall breast cancers;
- Ethnicity - Caucasian women tend to be affected more, but breast cancer is common in every ethnicity;
- Previous breast cancer - people who have had breast cancer are more likely to develop it again than those who have not had it;
- Alcohol - alcohol abuse increases the risk of developing many cancers, including breast cancer;
- Smoking - smoking is likely to increase the risk of breast cancer;
- Hormone replacement therapy (HRT) - when taken over a number of years HRT increases the risk of cancer. The risk of cancer increases with HRT that combines both progesterone and oestrogen. However, taking HRT for less than three years or using HRT with only oestrogen may not cause a significant increase in risk;
- Late menopause - women who begin menopause after the age of 55 are at higher risk;
- Not breastfeeding;
- Never giving birth, or having children after the age of 30;
- Obesity - people who are obese, especially postmenopausal women, are at increased risk;
- The contraceptive pill - the pill provides only a very small increase in risk, and;
- Exposure to radiation - this can be part of the reason people who have already had cancer are at increased risk of developing it again. Radiation from various scans and radiotherapy can increase breast cancer risk, but its use is also essential for diagnosing and treating the disease.
The type of breast cancer is determined by the type of cell it starts in.
Most breast cancers are ductal carcinomas, which begin in the lining of the milk ducts in breast tissue. Ductal carcinomas can be further classified as follows:
- Ductal carcinoma in situ - cancerous cells have not spread beyond the lining of the milk ducts, and;
- Invasive ductal carcinoma - cancerous cells in the milk ducts have spread to surrounding tissue.
This breast cancer originates in the lobules of the breasts, which are the glands that produce milk. Types of lobular carcinoma include:
- Lobular carcinoma in situ - cancerous cells in the lobules have not spread to other tissues, and;
- Invasive lobular carcinoma - cancerous cells have spread to other parts of the breast tissue and can spread to other parts of the body.
Treatment outcomes can vary greatly, depending on the stage of cancer. Cancer is staged according to the size and location of the primary tumour and whether it has spread to lymph nodes or organs throughout the body.
The tumour is 2 cm or less in diameter and small clusters may have spread to local lymph nodes.
Either a tumour that is 2 cm or less and has spread to 1-3 lymph nodes near the breast, or is 2-5 cm and has not spread to the lymph nodes.
The tumour is 2-5 cm and the cancer has spread to the lymph nodes, or is greater than 5 cm and has not spread to the lymph nodes.
A tumour of any size that has spread to 4-9 lymph nodes in the armpit or the breastbone, or a tumour larger than 5 cm, along with small clusters of cancer cells in lymph nodes, or a tumour greater than 5 cm that has spread to 1-3 local lymph nodes.
The tumour can be any size and has spread to the skin and/or the wall of the chest. It may also have spread to 9 or more lymph nodes in the armpit, or lymph nodes around the breastbone.
A tumour of any size that has spread to 10 or more lymph nodes in the armpit, or to lymph nodes around the breastbone or collarbone.
The cancer has spread to other body organs such as the lungs, bone, and brain.
Signs and symptoms
The following signs and symptoms of breast cancer may or may not be apparent:
- A lump or lumps in the breast;
- Changes in the size or shape of the breast;
- A hardening or swelling of part of the breast;
- Tightening of the nipple or pain in the nipple area;
- Discharge from the nipple (other than breastmilk);
- Armpit pain not associated with the menstrual period;
- A rash around one or both of the nipples, and;
- Dimpling in the breast skin.
Methods for diagnosis
Physical examination and breast awareness
Being aware of any changes in your breasts, such as lumps or changes in size or shape, can often be the first sign something is wrong and prompt you to see a doctor. A doctor or nurse will then perform a breast examination for lumps or changes in the breast and armpits.
There is no longer a recommendation for women to have routine examinations performed by a health professional.
Most commonly, a mammogram and/or an ultrasound are used to detect breast cancer. If a suspicious mass is detected with scanning, it will be biopsied for a definitive diagnosis. If a cancer is confirmed, then other forms of imaging may be used to further detail the mass, or to help determine if the tumour has spread to lymph nodes, organs or bones.
A range of different scans are used for diagnosing and monitoring breast cancer:
- A mammogram, which is an X-ray of the breast;
- An ultrasound, which uses sound waves to create an image of the breast;
- Magnetic resonance imaging (MRI), which uses magnetism instead of X-rays to create images. It can provide detailed images of tumours;
- Positron emission tomography (PET), which requires an injection with a radioactive label, or tracer, followed by a computerised tomography (CT) scan. It produces images that can help a doctor to assess the size, location and spread of a cancer, and;
- A bone scan. Like the PET scan, the bone scan involves an injection of radioactive material that highlights areas of high activity. It is used to determine if cancer has spread to the bones.
A sample of breast tissue (biopsy) is removed using a needle, followed by microscopic examination by a pathologist. This can confirm and characterise the cancer, which can help in selecting treatment options.
Types of treatment
A lumpectomy involves surgical removal of the cancerous tissue and some of the surrounding tissue. It is the least invasive of the surgical interventions for breast cancer and generally causes little or no change to the appearance of the breast.
This involves the partial removal of some of the breast tissue, the amount of which varies according to the size and shape of the tumour. It may involve a quarter of the breast or a segment.
This surgery is the complete removal of the breast. However, there are a number of ways that this can be defined:
- Simple, if it involves the complete removal of the breast;
- Skin-sparing, if the breast is removed but the skin is preserved, which allows for breast reconstruction;
- Radical, if in addition to the breast, the armpit lymph nodes and chest muscles are also removed, or;
- Modified radical, if the chest muscles remain intact.
Chemotherapy works by attacking cancer cells and stopping their reproduction. Various medications are used, which can be administered intravenously or orally.
There are three general types of chemotherapy:
- Neoadjuvant chemotherapy, which is given before surgery to help shrink the tumour prior to removal;
- Adjuvant chemotherapy, which is given after surgery with the aim of preventing recurrence of the cancer, and;
- Chemotherapy for advanced cancer, which uses combinations of medication, administered in cycles followed by a rest period. This is aimed at slowing the progression of the cancer.
Side effects occur because chemotherapy can also affect healthy cells. Your doctor will monitor your dosage carefully to ensure the optimal therapeutic dosage is achieved.
In this type of therapy, focused X-rays are applied to the area where the tumour is located. Another form of radiation therapy is brachytherapy. This involves inserting a small, radioactive implant in the tumour or the nearby area, which deliver cell-destroying radiation directly into the tumour. Radiotherapy can be used alone, or in addition to surgery and/or chemotherapy.
If the tumour contains receptors for oestrogen or progesterone hormones, hormone therapy is often used to block the action or lower the production of these hormones that are otherwise involved in supporting the growth of cancerous cells. Aromatase inhibitors can be used to block oestrogen production and tamoxifen and fulvestrant (not yet available in Australia) can be used to block oestrogen receptors on cancer cells. This is not the same as hormone replacement therapy given to menopausal women.
Some people diagnosed with breast cancer seek out complementary and alternative therapies. None of these alternative therapies are proven to cure cancer, but some can help people feel better when used together with conventional medical treatment. It is important to discuss any treatments with your doctor before starting them, since some complementary treatments can cause harm or interfere when combined with conventional cancer treatment.
Treatment side effects
There is a wide range of possible side effects from breast cancer treatments, including:
- Fat necrosis - radiotherapy can cause the death (necrosis) of fat cells in the breast;
- Radiation pneumonitis - radiotherapy can damage the lungs, resulting in inflammation. Radiation pneumonitis can progress to pulmonary fibrosis;
- Breast and pulmonary fibrosis - this is the thickening and scarring of tissue. Radiotherapy can cause fibrosis of the breast and lungs;
- Lactation difficulty - radiotherapy can cause vascular injury and damage glandular cells, resulting in difficulty with breastmilk production;
- Radiation-induced breast oedema - radiotherapy can result in swelling of the breast (oedema), which resolves over time but can progress to benign breast fibrosis;
- Secondary cancers - radiation-induced cancers are a rare complication of radiotherapy;
- Nausea, vomiting and fatigue from chemotherapy and radiotherapy. Whether or not the treatment makes you feel sick is not an indication of how well the treatment is working;
- Altered bowel habits - constipation frequently occurs during chemotherapy, probably as a result of anti-nausea medication and some pain-relief medication;
- Joint and muscle pain, which may occur after a treatment session and can last for a few days;
- Temporary hair loss on the head and body due to some types of chemotherapy. It will grow back after treatment has ended;
- Tingling in the hands and feet - some chemotherapeutic agents can affect the nerves. It is important to tell your doctor if you develop these symptoms, and;
- Early menopause - if you have breast cancer, but have not yet been through menopause, it is important to know that chemotherapy can affect your ability to become pregnant. Your periods may stop while you are having chemotherapy and may or may not return until several months after treatment ends, depending on whether or not you have an early menopause. If your periods return, they may not be as regular as they once were.
Advanced breast cancer
Inflammatory breast cancer can result in the swelling of the breast (oedema).
This is when the cancer spreads to other parts of the body through the bloodstream and lymphatic system. Generally, once breast cancer has spread to distant sites, it is not curable. However, treatments can be used to slow down the disease.
In 2010, the five-year survival rate for Australians with breast cancer was 89%. In general, the smaller the tumour, the higher the survival rate. For women who survive the first year, the survival rate increases to 90% and for women who survive the first five years, the forward five-year survival rate further increases to 93%. 
Five-year survival rates are calculated on people who were treated in the preceding five years. Advances in treatment since then might result in better outcomes for people with breast cancer today.
Being aware of changes in your breasts is important for the early detection of breast cancer. It would be good to talk to your doctor about any changes in the size and shape of your breasts, or the formation of lumps. Getting regular mammograms once you reach 50 years of age, maintaining a healthy weight, quitting smoking and reducing alcohol intake are the best means of preventing breast cancer. If you have a family history of breast cancer, you can talk to your doctor or genetic counsellor regarding your specific situation.