Worldwide, breast cancer is the most common invasive cancer in women.
(The most common form of cancer is non-invasive non-melanoma skin cancer; non-invasive cancers are generally easily cured, cause very few deaths, and are routinely excluded from cancer statistics.) Breast cancer comprises 22.9% of invasive cancers in women and 16% of all female cancers. In 2012, it comprised 25.2% of cancers diagnosed in women, making it the most common female cancer.
In 2008, breast cancer caused 458,503 deaths worldwide (13.7% of cancer deaths in women and 6.0% of all cancer deaths for men and women together). Lung cancer, the second most common cause of cancer-related death in women, caused 12.8% of cancer deaths in women (18.2% of all cancer deaths for men and women together).
Factors that are associated with an increased risk of breast cancer include:
Being female. Women are much more likely than men are to develop breast cancer.
Increasing age. Your risk of breast cancer increases as you age.
A personal history of breast cancer. If you’ve had breast cancer in one breast, you have an increased risk of developing cancer in the other breast.
A family history of breast cancer. If your mother, sister or daughter was diagnosed with breast cancer, particularly at a young age, your risk of breast cancer is increased. Still, the majority of people diagnosed with breast cancer have no family history of the disease.
Inherited genes that increase cancer risk. Certain gene mutations that increase the risk of breast cancer can be passed from parents to children. The most common gene mutations are referred to as BRCA1 and BRCA2. These genes can greatly increase your risk of breast cancer and other cancers, but they don’t make cancer inevitable.
Radiation exposure. If you received radiation treatments to your chest as a child or young adult, your risk of breast cancer is increased.
Obesity. Being obese increases your risk of breast cancer.
Beginning your period at a younger age. Beginning your period before age 12 increases your risk of breast cancer.
Beginning menopause at an older age. If you began menopause at an older age, you’re more likely to develop breast cancer.
Having your first child at an older age. Women who give birth to their first child after age 35 may have an increased risk of breast cancer.
Having never been pregnant. Women who have never been pregnant have a greater risk of breast cancer than do women who have had one or more pregnancies.
Postmenopausal hormone therapy. Women who take hormone therapy medications that combine estrogen and progesterone to treat the signs and symptoms of menopause have an increased risk of breast cancer. The risk of breast cancer decreases when women stop taking these medications.
Drinking alcohol. Drinking alcohol increases the risk of breast cancer.
Symptoms of breast cancer
Breast cancer can have a number of symptoms, but the first noticeable symptom is usually a lump or area of thickened breast tissue.
Most breast lumps aren’t cancerous, but it’s always best to have them checked by your doctor. You should also see your GP if you notice any of the following:
- A change in the size or shape of one or both breasts
- Discharge from either of your nipples (which may be streaked with blood)
- A lump or swelling in either of your armpits
- Dimpling on the skin of your breasts
- A rash on or around your nipple
- A change in the appearance of your nipple, such as becoming sunken into your breast
- Breast pain isn’t usually a symptom of breast cancer.
Types of breast cancer
There are several different types of breast cancer, which can develop in different parts of the breast. Breast cancer is often divided into non-invasive and invasive types.
Non-invasive breast cancer
Non-invasive breast cancer is also known as cancer or carcinoma in situ. This cancer is found in the ducts of the breast and hasn’t developed the ability to spread outside the breast.
This form of cancer rarely shows as a lump in the breast that can be felt, and is usually found on a mammogram (see below).The most common type of non-invasive cancer is ductal carcinoma in situ (DCIS).
Invasive breast cancer
Invasive cancer has the ability to spread outside the breast, although this doesn’t necessarily mean it has spread.
The most common form of breast cancer is invasive ductal breast cancer, which develops in the cells that line the breast ducts. Invasive ductal breast cancer accounts for about 80% of all breast cancer cases and is sometimes called “no special type”.
Other types of breast cancer
Other less common types of breast cancer include invasive lobular breast cancer, which develops in the cells that line the milk-producing lobules, inflammatory breast cancer and Paget’s disease of the breast.
It’s possible for breast cancer to spread to other parts of the body, usually through the lymph nodes (small glands that filter bacteria from the body) or the bloodstream. If this happens, it’s known as “secondary” or “metastatic” breast cancer.
Breast cancer screening
About one in eight women are diagnosed with breast cancer during their lifetime. There’s a good chance of recovery if it’s detected in its early stages. For this reason, it’s vital that women check their breasts regularly for any changes and always get any changes examined by their GP.
Mammographic screening (where X-ray images of the breast are taken) is the best available method of detecting an early breast lesion. However, you should be aware that a mammogram might fail to detect some breast cancers. It might also increase your chances of having extra tests and interventions, including surgery.
Women with a higher-than-average risk of developing breast cancer may be offered screening and genetic testing for the condition.
As the risk of breast cancer increases with age, all women who are 50-70 years old are invited for breast cancer screening every three years.
Women over 70 are also entitled to screening and can arrange an appointment through their GP or local screening unit.