Breast cancer is one of the most common cancers affecting females and is the second most common cause of death from cancer in women. Although predominately a disease of women, men can also get this disease. The outcome for breast cancer patients has improved significantly due to early diagnosis and better treatment.
Breast cancer is caused when normal breast cells change into abnormal cells. These cells grow in an abnormal manner and at an uncontrolled rate. This results in the formation of a breast lump which may grow larger within the breast, invade nearby structures such as the nipple or skin or spread outside of the breast. Common sites for breast cancer spread include the lymph nodes (glands) in the armpit or distantly to other organs such as the bones, liver, lungs and brain. Disease that has spread distantly is referred to as metastatic or secondary disease.
What are the Causes of Breast Cancer?
Studies have shown there are risk factors that increase the chance of developing breast cancer. Having a risk factor does not mean that someone will develop breast cancer. Some risk factors are things that cannot be changed – for example if there are other members in an individual’s family who have had breast cancer. Other risk factors can be modified, such as lifestyle changes. The list below outlines some of these risk factors and indicates some lifestyle changes that could be made to reduce the risk of breast cancer:
- Age: This is the main risk factor for breast cancer. The older a woman is, the greater the risk of developing breast cancer.
- Gender: Breast cancer occurs approximately 100 times more commonly in women than in men
- Previous breast disease or breast cancer: Women who have previously had particular types of benign breast abnormalities, known as proliferative lesions, are at an increased risk of breast cancer, especially if the cells making up these abnormalities were ‘atypical’.
- Family history: This is an important risk factor, however only 1 in 5 women will have a first-degree relative (either a parent or sibling) who have had breast cancer. Less than 10 percent of all breast cancers are actually associated with genetic errors (mutation) that is inherited from a parent. Mutations in two main breast cancer genes, BRCA1 and BRCA2, are associated with increased risk of breast cancer
- Weight: Weight gain and obesity are associated with a higher risk of breast cancer in women who have gone through menopause.
- Menopausal hormonal therapy: long term use of hormone replacement therapy that contains a combination of two hormones – oestrogen and progesterone – may increase the risk of breast cancer in women aged 50-79.
- Age of first period and age of menopause- women who are younger when their periods start and who are older when menopause begins are at an increased breast cancer risk. This is likely related to overall exposure to oestrogen over a woman’s lifetime.
- Pregnancy: Women who have never given birth are more likely to develop breast cancer after menopause than women who have given birth multiple times. In addition, the younger a woman is at her first full-term pregnancy the lower her risk of breast cancer.
- Breastfeeding: Breastfeeding has been found to be protective against developing breast cancer.
- Physical activity: Physical exercise appears to protect against breast cancer in women.
- Alcohol: There is a relationship between alcohol consumption and an increased risk of breast cancer. The risk increases with greater alcohol consumption.
- Smoking: Both passive and active tobacco smoking is associated with an increased risk of breast cancer, especially amongst women who have not gone through menopause. This risk is associated with younger age of starting smoking, longer duration of smoking, and increased number of cigarettes per day. It also appears to be higher in genetically susceptible groups of women.
- Diet: There has been no definitive evidence linking specific foods or dietary patterns with an increased or decreased risk of breast cancer. Some studies have shown that consumption of a diet composed predominantly of fruits and vegetables results in a lower risk of breast cancer. An association between a high intake of dietary fat and breast cancer has been seen in some studies, although the overall effect is small. Eating more than five servings of red meat per week may be associated with an increased risk of hormone-positive premenopausal breast cancer. There is no evidence for an effect of intake of vitamin A, E, or C or beta-carotene on breast cancer risk.
- Exposure to ionizing radiation: If this occurs at a young age, such as for women treated with radiation for Hodgkin lymphoma or survivors of atomic bombs, there is an increased risk of breast cancer.
- Night shift work: Women who work at night have a higher risk of breast cancer compared to women who do not do night-shifts. The causes for this are uncertain.
Lifestyle Changes that Might Reduce the Risk of Breast Cancer?
Some of the following changes (if feasible for you) may reduce your risk of breast cancer. Sometimes the advantages of these changes need to be weighed against the disadvantages e.g. hormone replacement therapy for severe menopausal symptoms. This should be discussed with your doctor.
- Plan for first birth before the age of 30
- Breastfeed for at least six months
- Avoid or limit the duration of postmenopausal hormone therapy
- Quit smoking
- Limit alcohol intake
- Maintain a healthy weight
- Limit nocturnal shift work
- Adopt a physically active lifestyle
What are the Symptoms of Breast Cancer?
In Australia and New Zealand, there is an established breast cancer screening program. In these countries, breast cancer for most women will be found due to an abnormal mammogram (specialized breast X-ray). The most common symptom that a woman may experience is a lump in the breast. Breast lumps that are cancer typically feel hard, irregular and immobile. Lumps are usually not painful but in <10% of women, a lump in the breast is sore. Other symptoms that may occur include:
- Change to the size or shape of the breast
- Lumps in the armpits
- Changes to the skin of the breast such as discolouration, redness, thickening or dimpling of the skin
- Changes to the nipple such as discharge from the nipple or inversion (pulling inwards of the nipple if it normally points outwards)
What are the Treatments for Breast Cancer?
The treatments available for breast cancer include surgery, radiation therapy, chemotherapy, hormonal therapy and targeted therapy. The choice of treatment will depend on the type of breast cancer as well as the extent of disease and personal risk factors. A team of doctors including surgeons, radiation oncologists, medical oncologists and pathologists will decide together on the best treatment plan for each patient. This team is often referred to as the Multidisciplinary Team (MDT).
Surgery is usually the first step in the treatment of breast cancer. There are two main types of surgery that a woman with breast cancer may undergo. The first type of surgery is called a mastectomy, which means the removal of the entire breast. After a mastectomy, a woman may choose to undergo reconstruction/plastic surgery at the time of initial surgery or at a later stage. Other women may choose not to undergo reconstruction and may choose to wear a special bra and/or breast prosthesis to provide a breast shape.
The other type of surgery is breast-conserving surgery, otherwise known as a lumpectomy or a wide local excision. In this type of surgery, the surgeon will remove the cancer with a small section of healthy breast tissue around the cancer. This section of healthy tissue around the cancer is referred to as the ‘margin’. Surgery to the armpit on the same side as the breast cancer is also common. This may involve the removal of one or two nodes (a sentinel lymph node biopsy) or removal of most of the lymph nodes in the armpit (axillary dissection).
Radiation therapy (also called radiotherapy) is an important component of breast cancer treatment. Radiation therapy is a targeted treatment using X-rays, that aims to kill any cancer cells or tumour deposits that may remain after surgery. Radiation therapy has been proven to decrease the chance of breast cancer recurring after surgery. Radiation therapy can be used to treat the remaining breast tissue after breast conserving surgery, the chest wall after mastectomy and/or lymph nodes around the breast.
Radiation therapy to the breast is recommended for most patients after breast conserving surgery. In selected cases an extra ‘boost’ of radiation to the area of the breast where the cancer was removed may be recommended.
Radiation therapy to the chest wall after mastectomy may be recommended depending on the individual characteristics of the patient’s breast cancer. Areas around the breast that contain lymph nodes, such as in the armpit, above the collar bone or under the breast bone may also be treated with radiation therapy if a patient is at risk of cancer spreading to these lymph nodes.
External beam radiation therapy (EBRT) is the most common type of radiation therapy used in breast cancer treatment. External beam radiation therapy is usually delivered once a day, five days a week from Monday to Friday. The total length of treatment can range from 3-6 weeks. Another type of radiation therapy that is less commonly used to treat breast cancer is Brachytherapy. Novel approaches of radiation therapy which are being investigated include intraoperative radiation therapy and partial breast radiation therapy.
Systemic therapy for breast cancer refers to the use of medications (tablets or injections) that include hormone therapy, chemotherapy and/or biological therapy, also called, ‘targeted’ therapy. Specific information about an individual’s breast cancer will determine whether systemic therapy is required and which type of treatment should be used. This specific information mainly comes from the pathologist’s report and special tests done on the cancer tissue.
When a breast cancer specimen is looked at under a microscope, the grade of the breast cancer is determined based on the aggressiveness of the individual cancer cells. The presence or absence of certain proteins on the cancer cells is also assessed. These proteins are the hormone receptors (oestrogen and progesterone receptors) and the HER2 receptor. The number of lymph nodes that have cancer cells in them is also important when deciding on the types of systemic therapy.
Hormone therapy is used to treat the types of breast cancers that are hormone receptor positive. This means that the breast cancer grows in response to hormones such as oestrogen or progesterone. Hormone therapy aims to decrease the chance of breast cancers recurring in the same breast or in the other breast. Hormone therapy works by either blocking the hormones acting on the breast cancer cells or preventing the body from making certain kinds of hormones
Chemotherapy is used for certain patients. Circumstances where chemotherapy may be considered include patients with high-risk features such as a high grade tumour, large tumour size or lymph node involvement. Chemotherapy may be used before or after surgery depending upon the situation. Chemotherapy is commonly used in breast cancers that have negative hormone receptors.
Targeted therapy is used in breast cancers that over express the HER2 protein. The HER2 protein is present in approximately 20% of breast cancers. The monoclonal antibody Herceptin and other targeted therapies have been developed to treat these cancers.
What are the Side Effects of Radiation Therapy?
The potential side effects of radiation therapy for breast cancer are divided into acute side effects (can occur during and shortly after treatment) and late effects (can occur months to years after treatment) and depend upon the areas treated.
Side effects during/soon after treatment (Early or ‘acute’ side effects)
General – Fatigue is common in the second half of treatment and is very variable between patients. Fatigue may persist for several weeks after treatment.
Local – All other side effects of radiation therapy come from the structures/organs in and just next to where the radiation is being targeted.
Skin reddening and irritation– The skin can become increasingly red and itchy during treatment. Sometimes there can be skin peeling most commonly occurring under the breast or in the lower armpit due to rubbing of the skin in these areas. The peak of the reaction occurs 7-14 days after the treatment finishes. Occasionally there may be aches and pains in the breast or chest wall, but pain medications are rarely required.
Loss of hair (alopecia) – Hair in the armpit may fall out during or after radiation treatment. If hair loss occurs, it may be permanent.
What can help reduce acute side effects?
Resting as needed can help with fatigue. During treatment your Radiation Oncology team will provide advice on creams and dressings based on the degree of your skin reaction. Special creams can be used for itchy skin and if pain develops in the breast, pain medications can be prescribed.
Early-delayed side effects (side effects occurring weeks to 6 months after treatment)
Inflammation of the lung (pneumonitis) – This is an uncommon side effect occurring after breast irradiation. It can occur 6 weeks to 6 months following treatment. Symptoms most commonly include a dry cough and shortness of breath. Short-term corticosteroid medication are rarely needed to improve symptoms.
Breast Swelling – mild swelling can occur after treatment. The swelling can take several months after treatment to resolve.
Side effects well after treatment (Late or long-term side effects)
Late side effects may occur a few months to years after treatment. They are more rare than early side effects. Depending on the problem, it may occur only once and then resolve or may be more persistent over the long term or may come and go over time.
Skin changes – If permanent skin changes occur after radiation treatment they are usually minimal. Occasionally the skin can be a little lighter or darker in the regions that have received radiation. Tiny blood vessels under the skin may become swollen and more prominent (telangiectasias) over time. Increased firmness in the breast may also occur with variable changes in appearance or shape compared to the other breast.
Rib fracture – Radiation can weaken the ribs located underneath the treated breast or chest wall, which can increase the risk of a fracture. This risk of rib fracture is 1%.
Lung scarring (fibrosis) – This may occur in the small amount of lung that receives radiation just under the breast and chest wall. The scarring may be visible on a chest x-ray but is not expected to cause symptoms.
Heart – If the left breast or chest wall is being treated, there is a low risk of damage to the heart and a small increased risk of heart disease. Radiation treatment techniques (deep inspiration breath hold) are now being used more commonly to reduce the amount of radiation to the heart to as low as possible.
Swelling of the arm (lymphoedema) – The risk of developing lymphoedema is approximately 5% if the lymph nodes located above the collar bone and/or armpit are treated. If lymphoedema occurs, it is usually mild to moderate but can rarely be severe.
Damage to the nerves that control the arm and hand (brachial plexopathy) – This is an extremely rare side effect that may occur if the lymph nodes above the collar bone and/or armpit are treated. Symptoms may include pain, numbness and weakness in the arm and hand.
Radiation induced cancers – Any exposure to radiation increases the risk of a second cancer developing in that area, usually decades later. This risk is not entirely attributable to radiation received as part of your treatment. All X-rays and scans received over your lifetime contribute to this risk, as does unavoidable exposure to environmental radiation. The risk of a cancer being caused by radiation therapy is in the order of 0.5 – 1% at 10 years.
What can be done to treat late side effects?
If the glands above the collar bone and/or armpit are treated and lymphoedema occurs, advice from a specialist nurse is required. Management may include exercises, compression garments and massage therapy. To minimise the risk of developing heart problems after radiation it is important to lead a healthy lifestyle and prevent or treat medical conditions that can increase the risk of heart problems.
The best person to discuss radiation therapy for breast cancer is a Radiation Oncologist. You can ask your Surgeon or General Practitioner for a referral to a Radiation Oncologist for a discussion about whether radiation therapy is a suitable treatment option for you.
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Page last updated: 15/07/2020