Advances in screening and treatment have improved survival rates dramatically since 1989. There are around 3.1 million breast cancer survivors in the United States (U.S.). The chance of any woman dying from breast cancer is around 1 in 37, or 2.7 percent.
In 2017, around 252, 710 new diagnoses of breast cancer are expected in women, and around 40,610 women are likely to die from the disease.
Awareness of the symptoms and the need for screening are important ways of reducing the risk.
Breast cancer can affect men too, but this article will focus on breast cancer in women.
Fast facts on breast cancer:
Here are some key points about breast cancer. More detail is in the main article.
- Breast cancer is the most common cancer among women.
- Symptoms include a lump or thickening of the breast, and changes to the skin or the nipple.
- Risk factors can be genetic, but some lifestyle factors, such as alcohol intake, make it more likely to happen.
- A range of treatments is available, including surgery, radiation therapy, and chemotherapy.
- Many breast lumps are not cancerous, but any woman who is concerned about a lump or change should see a doctor.
The first symptoms of breast cancer are usually an area of thickened tissue in the breast, or a lump in the breast or in an armpit.
Other symptoms include:
- a pain in the armpits or breast that does not change with the monthly cycle
- pitting or redness of the skin of the breast, like the skin of an orange
- a rash around or on one of the nipples
- a discharge from a nipple, possibly containing blood
- a sunken or inverted nipple
- a change in the size or shape of the breast
- peeling, flaking, or scaling of the skin on the breast or nipple
Cancer is staged according to the size of the tumor and whether it has spread to lymph nodes or other parts of the body.
There are different ways of staging breast cancer. One way is from stage 0 to 4, but these may be broken down into smaller stages.
Stage 0: Known as ductal carcinoma in situ (DCIS), the cells are limited to within a duct and have not invaded surrounding tissues.
Stage 1: At the beginning of this stage, the tumor is up to 2 centimeters (cm) across and it has not affected any lymph nodes.
Stage 2: The tumor is 2 cm across and it has started to spread to nearby nodes.
Stage 3: The tumor is up to 5 cm across and it may have spread to some lymph nodes.
Stage 4: The cancer has spread to distant organs, especially the bones, liver, brain, or lungs.
After puberty, a woman’s breast consists of fat, connective tissue, and thousands of lobules, tiny glands that produce milk for breast-feeding. Tiny tubes, or ducts, carry the milk toward the nipple.
In cancer, the body’s cells multiply uncontrollably. It is the excessive cell growth that causes cancer.
Breast cancer usually starts in the inner lining of milk ducts or the lobules that supply them with milk. From there, it can spread to other parts of the body.
The exact cause remains unclear, but some risk factors make it more likely. Some of these are preventable.
The risk increases with age. At 20 years, the chance of developing breast cancer in the next decade is 0.6 percent. By the age of 70 years, this figure goes up to 3.84 percent.
If a close relative has or has had, breast cancer, the risk is higher.
Women who carry the BRCA1 and BRCA2 genes have a higher risk of developing breast cancer, ovarian cancer or both. These genes can be inherited. TP53 is another gene that is linked to a greater breast cancer risk.
3. A history of breast cancer or breast lumps
Women who have had breast cancer before are more likely to have it again, compared with those who have no history of the disease.
Having some types of benign, or non-cancerous breast lumps increases the chance of developing cancer later on. Examples include atypical ductal hyperplasia or lobular carcinoma in situ.
4. Dense breast tissue
Breast cancer is more likely to develop in higher density breast tissue.
5. Estrogen exposure and breast-feeding
Being exposed to estrogen for a longer period appears to increase the risk of breast cancer.
This could be due to starting periods earlier or entering menopause later than average. Between these times, estrogen levels are higher.
Breast-feeding, especially for over 1 year, appears to reduce the chance of developing breast cancer, possibly because pregnancy followed by breastfeeding reduces exposure to estrogen.
6. Body weight
Women who are overweight or have obesity after menopause may have a higher risk of developing breast cancer, possibly due to higher levels of estrogen. High sugar intake may also be a factor.
7. Alcohol consumption
A higher rate of regular alcohol consumption appears to play a role. Studies have shown that women who consume more than 3 drinks a day have a 1.5 times higher risk.
8. Radiation exposure
Undergoing radiation treatment for a cancer that is not breast cancer increases the risk of breast cancer later in life.
9. Hormone treatments
The use of hormone replacement therapy (HRT) and oral birth control pills have been linked to breast cancer, due to increased levels of estrogen.
10. Occupational hazards
In 2012, researchers concluded that exposure to certain carcinogens and endocrine disruptors, for example in the workplace, could be linked to breast cancer.
In 2007, scientists suggested that working night shifts could increase the risk of breast cancer, but more recent research concludes this is unlikely.
Cosmetic implants and breast cancer survival
Women with cosmetic breast implants who are diagnosed with breast cancer have a higher risk of dying from the disease and a 25 percent higher chance of being diagnosed at a later stage, compared with women without implants.
This could be due to due to the implants masking cancer during screening, or because the implants bring about changes in breast tissue. More research is needed.
Breast cancer can be:
- Ductal carcinoma: This begins in the milk duct and is the most common type.
- Lobular carcinoma: This starts in the lobules.
Invasive breast cancer is when the cancer cells break out from inside the lobules or ducts and invade nearby tissue, increasing the chance of spreading to other parts of the body.
Non-invasive breast cancer is when the cancer is still inside its place of origin and has not broken out. However, these cells can eventually develop into invasive breast cancer.
Breast cancer can also affect men, but it is less common in men than in women.