Breast Cancer Screening
It is important to understand that most breast lumps are benign and are not cancer. Breast cancer cells usually form a tumour that can often be seen on an x-ray or felt as a lump. Breast cancer occurs almost entirely in women but men can also get breast cancer. Some types of benign breast lumps can increase a woman’s risk of getting breast cancer. Any breast lump or change needs to be checked by a physician.
Breast cancers can start from different parts of the breast:
- Most breast cancers begin in the ducts that carry mutations to the nipple (ductal cancers).
- Some start in the glands that make breast milk (lobular cancers).
- There are also other types of breast cancer that are less common like phyllodes tumour and angiosarcoma.
- A small number of cancers start in other tissues in the breast. These cancers are called sarcomas and lymphomas and are not really thought of as breast cancers.
Changes or mutations in DNA can cause normal breast cells to become cancer. Certain DNA changes are inherited. These can greatly increase the risk for breast cancer.
Other lifestyle related risk factors, such as what you eat and how much you exercise can increase your chance of developing breast cancer. But it is not yet known exactly how some of these risk factors cause normal cells to become cancer. Hormones seem to play a role in many cases of breast cancer, but just how this happens is not fully understood.
Proto-oncogenes
Proto-oncogenes are genes that help cells grow normally. When a proto-oncogene mutates or there are too many copies of it, it becomes a “bad” gene that can stay turned on or activated when it’s not supposed to be. When this happens, the cell grows out of control and makes more cells that grow out of control. This can lead to cancer. This bad gene is called an oncogene.
Tumour suppressor genes
Tumour suppressor genes are normal genes that slow down cell division, repair DNA mistakes, or tell cells when to die. When tumour suppressor genes don’t work properly, cells can grow out of control, make more cells that grow out of control, and cells don’t die when they should, which can lead to cancer.
Inherited gene changes
Certain inherited DNA mutations can dramatically increase the risk for developing certain cancers and are linked to many other cancers that run in families, for instance with BRCA genes. BRCA 1 and 2 are tumour suppressor genes. When one of these genes changes, they no longer suppress cell growth and cancer is more likely to develop. A change in one of these genes can be passed from a parent to a child.
Genetic testing can identify patients who have mutations in the BRCA1 or BRCA2 tumour suppressor genes or less commonly other genes such as PALB2, ATM or CHEK2.
These women can then decide to take steps to reduce their risk of breast cancer by increasing awareness of their breasts and following appropriate screening recommendations to help find cancer at an earlier, more treatable stage.
As these mutations are also associated with other cancers, screening and preventative action is suggested for these as well.
Acquired gene changes
Most DNA mutations related to breast cancer take place in breast cells during a woman’s life rather than having been inherited. These acquired mutations of oncogenes and/or tumour suppressor genes may result from other factors, such as radiation or cancer-causing chemicals. So far, the causes of most acquired mutations that could lead to breast cancer are still unknown.
How common is breast cancer?
Breast cancer is the most common cancer in women, except for skin cancers, currently the average risk of a woman developing breast cancer sometime in her life is about 13%. This means that there is a 1 in 8 chance that she will develop breast cancer. However, this also means there is a 7 in 8 chance that she will never have the disease.
Breast cancer is the second leading cause of cancer death in women and only lung cancer kills more. The chance that a woman will die from breast cancer is about 1 in 38 that is 2.6%.
Since 2007 in the United States, breast cancer death rates have been steady in women younger than 50, but have continued to decrease in older women. From 2013 to 2017 the death rate decreased by 1.3% per year. These decreases are believed to be the result of finding breast cancer earlier through screening and increased awareness, as well as better treatments..
Breast cancer researchers throughout the world are working to find better ways to prevent, detect, and treat breast cancer, and to advise the patients.
Studies continue to uncover lifestyle factors and habits, as well as inherited genes, which can affect breast cancer risk. For example:
- The effects of exercise, weight gain or loss and diet-related risk.
- The best use of genetic testing such as cancer mutations.
- Common gene variations. Some small changes in genes that are not a significant mutations may affect breast cancer risk. Gene variants have only a modest effect on risk, when taken together they could have a large impact.
Environmental causes of breast cancer have also received more attention in recent years. While much of the science is still in its earliest stage, this is an area of active research.
Breast cancer risk factors that cannot be changed:
- Female
This is the main risk for breast cancer. Men can get breast cancer, too, but this disease is much more common in women.
- Age
As you get older, your risk of breast cancer goes up. Most breast cancers are started in women aged 55 and older.
- Inherited certain gene changes
About 5-10% of breast cancer cases are thought to be hereditary, meaning they result directly from gene changes passed on from a parent to a child.
BRCA1 and BRCA2
The most common cause for hereditary breast cancer and is an inherited mutation in the BRCA1 or BRCA2 gene. In normal cells, these genes help make proteins that repair damaged DNA. Mutated versions of these genes can lead to abnormal cell growth, which can lead to cancer.
If you have inherited a mutated copy of either gene from a parent, you have a higher risk of breast cancer.
On average, a woman with a BRCA1 or BRCA2 gene mutation has up to a 7 in 10 chance of getting breast cancer by age 80. This risk is also affected by how many other family members have had breast cancer. It goes up if more family members are affected.
Women with one of these mutations are more likely to be diagnosed with breast cancer at a younger age, as well as to have cancer in both breasts.
Women with one of these gene changes also have a higher risk of developing ovarian cancer and some other cancers.
Men who inherit one of these gene changes also have a higher risk of breast cancer, as well as prostate and some other cancers.
BRCA mutations are more common in Ashkenazi Jewish origin than in other racial or ethnic groups although anyone can have them.
- Other genes
Other genes can also lead to inherited breast cancers. These gene mutations are much less common, and most of them do not increase the risk of breast cancer as much as the BRCA genes:
ATM
The ATM gene normally helps repair damaged DNA. Inherited mutations with two abnormal copies of this gene causes the disease ataxia-telangiectasia. Inheriting one abnormal copy of this gene has been linked to higher rate of breast cancer in some families.
TP53
The TP53 gene helps stop the growth of cells with damaged DNA. Inherited mutations in this gene cause Li-Fraumeni syndrome. People with this syndrome have an increased risk of breast cancer as well as other cancers such as leukaemia, brain tumours and other problems. This mutation is a rare cause of breast cancer.
CHEK2
The CHEK2 gene is another gene that normally helps with DNA repair. This mutation increases breast cancer risk.
PTEN
The PTEN gene normally helps regulate cell growth, inherited mutations in this gene can cause Cowden syndrome. This is a rare disorder of high risk of breast cancer and benign (non-cancer) tumours in the breast, as well as growths in the digestive tract, thyroid, uterus and ovaries.
CDH1
Inherited mutations in this gene cause hereditary diffuse gastric cancer, a syndrome in which people develop a rare type of stomach cancer. Women with mutations in this gene can also have an increased risk of invasive lobular breast cancer.
STK11
Defects in this gene can lead to Peutz-Jeghers syndrome. People affected with this disorder have pigmented spots on their lips and in their mouths, polyps in the urinary and digestive tracts, and a higher risk of many types of cancer, including breast cancer
PALB2
The PALB2 gene makes a protein that interacts with the protein made by the BRCA2 gene. Mutations in this gene can lead to a higher risk of breast cancer.
Mutations in several other genes have been linked to breast cancer, but these account for small number of cases. Counselling and genetic testing can be done to look for inherited mutations. This is a definite option for patients who have a strong family history or who have been diagnosed with breast cancer.
It’s important to note that most women who get breast cancer do not have a family history of the disease. But women who have close blood relatives with breast cancer have a higher risk:
- Having a first degree relative, that is mother, sister or daughter with breast cancer almost doubles a woman’s risk. Having two first degree relatives increases the risk about three times.
- Women with a father or brother who has had breast cancer also have a higher risk of breast cancer.
Overall about 15% of women with breast cancer have a family member with the disease.
- Personal history of breast cancer
A woman with cancer in one breast has a higher risk of developing a new cancer in the other breast or in another part of the same breast. This is different from a recurrence or return of the first cancer. Although this risk is low overall, it’s even higher for younger women with breast cancer.
- Race and ethnicity
Overall, white women are slightly more likely to develop breast cancer than African American women, although the gap between them has been closing in recent years. In women under age 45, breast cancer is more common in African American women. African American women are also more likely to die from breast cancer at any age. Asian, Hispanic, and Native American women have a lower risk of developing and dying from breast cancer.
Risk in different groups also varies by type of breast cancer. For example, African American women are more likely to have the less common triple-negative breast cancer.
- Being tall
Many studies have found that taller women have a higher risk of breast cancer than shorter women. The reasons for this aren’t exactly clear, but it may have something to do with factors that affect early growth, such as nutrition early in life, as well as hormonal or genetic factors.
- Dense breast and fatty tissue, fibrous tissue, and glandular tissue
Breasts appear denser on a mammogram when they have more glandular and fibrous tissue and less fatty tissue. Women with dense breasts on mammogram have a risk of breast cancer that is about 1 1/2 to 2 times that of women with average breast density.
Unfortunately, dense breasts can also make it harder to see cancers on mammograms. Age, menopausal status and the use of certain drugs, pregnancy and genetics influence breast density.
- Benign breast conditions
Women diagnosed with certain benign breast conditions have a higher risk of breast cancer. Some of these conditions are more closely linked to breast cancer risk than others.
Non-proliferative lesions
These conditions don’t seem to affect breast cancer risk, or if they do, the increase in risk is very small. They include:
- Fibrosis and/or simple cysts, sometimes called fibrocystic changes.
- Mild hyperplasia.
- Adenosis.
- Phyllodes tumour benign.
- A single papilloma.
- Fatty necrosis.
- Duct ectasia.
- Periductal fibrosis.
- Squamous and apocrine metaplasia.
- Epithelial-related calcification.
- Other tumours (lipoma, haematoma, haemangioma, neurofibroma, adenomyoepithelioma).
Mastitis is not a tumour and does not increase the risk.
Proliferative lesions without atypia (cell abnormalities).
These can just be excessive growth of cells in the ducts or lobules of the breast, but the cells don’t look very abnormal.
These conditions seem to raise a woman’s risk of breast cancer slightly. They include:
- Usual ductal hyperplasia
- Fibroadenoma.
- Sclerosing adenosis.
- Several papillomas.
- Radial scar.
Proliferative lesions with atypia
In these conditions, the cells and the ducts where the breast tissue grow excessively, and some of them no longer look normal. These types of lesions include:
- Atypical ductal hyperplasia
- Atypical lobular hyperplasia.
Breast cancer risk is about four to five times higher than normal in women with these changes. If a woman also has a family history of breast cancer and either hyperplasia or atypical hyperplasia, she has an even higher risk of breast cancer.
Lobular carcinoma in situ (LCIS)
In LCIS, cells that look like cancer cells are growing in the lobules of the milk-producing glands of the breast, but they are not growing through the wall of the lobules. LCIS is not considered to be cancer, and it typically does not spread beyond the lobule if it isn’t treated. But women with LCIS have a 7 to 12 times higher risk of developing breast cancer, which can be in either breast.
Early menstrual periods
Early menstrual periods in women who have had more menstrual cycles because they started to menstruate early (especially before the age of 12) have a slightly higher risk of breast cancer. The increase in risk may be due to a longer lifetime exposure to the hormones oestrogen and progesterone.
Menopause after the age of 55
Women who have had more menstrual cycles because they went through menopause later have a slightly higher risk of breast cancer. The increase in risk may be because they have a longer lifetime exposure to the hormones oestrogen and progesterone.
Radiotherapy to the chest
Women who have been treated with radiation therapy to the chest for another cancer (such as Hodgkin’s or non-Hodgkin’s lymphoma) when they were younger have a significantly higher risk of breast cancer. Risk depends on their age when they get radiation. The risk is highest for women who have radiation as a teen or young adult, when the breasts are still developing. Radiation treatment in older women (after the age of 40 or 45) does not seem to increase the breast cancer risk.
Exposure to Diethylstilbestrol
In the 1940s to early 1970s some pregnant women were given an oestrogen-like drug called DES because it thought to lower the chance of losing the baby and having a miscarriage. These women have a slightly increased risk of developing breast cancer. Women whose mothers took DES during pregnancy may also have a slightly higher risk of breast cancer.
Lifestyle-related breast cancer risk factors:
- Alcohol
Drinking alcohol is clearly linked to an increased risk of breast cancer. The risk increases with the amount of alcohol consumed. Women who have 1 alcoholic drink a day have a small (about 7% to 10%) increase in risk compared with non-drinkers, while women who have 2 to 3 drinks a day have about a 20% higher risk than non-drinkers. Alcohol is linked to an increased risk of other types of cancer, too.
- Being overweight
Being overweight or obese after menopause increases breast cancer risk. Before menopause, your ovaries make most of your oestrogen, and fat tissue makes only a small part of the total amount. After menopause (when the ovaries stop making oestrogen), most of a woman’s oestrogen comes from fat tissue. Having more fat tissue after menopause can raise oestrogen levels and increase your chance of getting breast cancer. Also, women who are overweight tend to have higher blood insulin levels. Higher insulin levels have been linked to some cancers, including breast cancer.
However, this link between being overweight and breast cancer is complex. Being overweight after menopause is more strongly linked to an increased risk of hormone receptor-positive breast cancer, whereas being overweight before the menopause might increase your risk of a less common triple-negative breast cancer.
- Physical activity
Evidence is growing that regular physical activity reduces breast cancer risk, especially in women past menopause. How much is required though?
Exactly how physical activity might reduce breast cancer risk isn’t clear, but it may be due to its effects on body weight, inflammation, hormones, and energy balance.
- Not having children
Women who have not had children or who had their first child but after the age of 30 have a slightly higher breast cancer risk overall. Having many pregnancies and becoming pregnant in early age reduces breast cancer risk.
However, this risk is complex, for example, the risk of breast cancer is higher for about the first decade after having a child, particularly for hormone receptor-negative breast cancer (including the less common triple-negative breast cancer). The risk then becomes lower over time.
- Not breastfeeding
Most studies suggest that breastfeeding may slightly lower breast cancer risk, especially if it is continued for a year or more. The explanations for this may be that breastfeeding reduces a women’s total number of lifetime menstrual cycles.
- Birth control
Some birth control methods use hormones, which might increase breast cancer risk.
Oral contraceptives
Most studies have found that women using oral contraceptives have a slightly higher risk of breast cancer than women who have never used them. Once the pills are stopped, this risk seems to go back to normal within about 10 years.
Injectable birth control
Depo-Provera is an injectable form of progesterone that’s given once every three months of birth control. Some studies have found that a woman currently using birth control Depo seemed to have an increase in breast cancer risk, but other studies have not found an increased risk.
Birth control implants, IUDs, skin patches, and vaginal rings
These also use hormones, which in theory could lead to increased risk of breast cancer. Some studies have shown a link between use of hormone-releasing IUDs and breast cancer risk, but few studies have looked at the use of birth control implants, patches, and rings and breast cancer risk.
- HRT
Hormone therapy with oestrogen (often combined with progesterone) has been used for many years to help relieve the symptoms of the menopause and help prevent osteoporosis.
Combined HRT
Use after the menopause increases the risk of breast cancer. This increase in risk after about four years of use. Combined hormone therapy also increases the likelihood that the cancer may be found at a more advanced age. This increased risk appears to apply only or mainly to current recent users. A woman’s breast cancer risk seems to go back by about five years since stopping treatment.
Bioidentical hormone therapy
These are hormones which are suggested to have the same chemical structures as those found naturally in people, as opposed to the manufactured ones. There have been very few studies comparing bioidentical or natural hormones to synthetic versions of hormones. There’s no proof that they are safer or more effective. More research is required. Until this effect is validated, the use of these bioidentical hormones should be considered to have the same health risk as any other type of hormone replacement therapy.
Oestrogen therapy
Studies of oestrogen alone after menopause have had mixed results, with some finding a slightly higher risk and some finding no increase. If oestrogen therapy alone does increase the risk of breast cancer, it is not by much
- Breast implants
Breast implants has not been linked with the increased risk of the most common type of breast cancer. However, they have been linked to a rare type of non-Hodgkins lymphoma called breast implant-associated anaplastic large cell lymphoma, which can form in the scar tissue around the implant. This lymphoma appears to happen more often in implants with textured (rough) surfaces rather than smooth surfaces.
If this tumour does occur after an implant, it can start as a lump, a collection of fluid, swelling, or pain near the implant, or as a change in breast size or shape.
Factors with unclear effects on the breast cancer risk
- Diet and vitamins
Whilst being overweight or not physically active have been linked to breast cancer risk, the possible link between diet and breast cancer risk is unclear and inconclusive.
Studies have shown that breast cancer is less common in countries where the typical diet is low in total fat, low in polyunsaturated fat, and low in saturated fat. However, this is complicated by other variables, such as activity, intake of other nutrients and genetic factors that might also affect breast cancer risk.
However, it is known that high-fat diets can lead to being overweight or obese, which is a known breast cancer risk factor. A certain type of fat intake is clearly linked to a higher risk of heart disease.
Some studies have suggested that diets high in fruits and vegetables and calcium-rich dairy products, but low in red and processed meats might lower the risk of breast cancer. This area needs to be researched more.
Studies looking at women in Asian countries have found that diets high in soy products might lower breast cancer risk. But this link is not as clear in studies looking at women in Western countries. This might be because Asian women generally eat more soy products (and start at an earlier age) than Western women.
Vitamins levels in the body
There is no strong evidence that taking vitamins reduces the risk of breast cancer.
- Chemicals in the environment
Chemicals in the environment that have oestrogen-like properties may increase breast cancer risk. For example, some plastics, certain cosmetics and personal care products, pesticides, and polychlorinated biphenyls appear to have this property. More research is required.
- Tobacco smoke
Some studies have found that heavy smoking over a longer period of time may be linked to a slightly higher risk of breast cancer. There is therefore suggested but not sufficient evidence that smoking increases the risk of breast cancer.
- Nightshift work
Some studies have suggested that women who work at night, such as nurses, might have an increased risk of breast cancer. This is an area of research and may be related to levels of melatonin.
So How Can we Lower our Breast Cancer Risk?
- Stay at a healthy weight.
- Be physically active.
- Avoid or limit alcohol.
If you have an increased risk of breast cancer
If you have the BRCA1 or BRCA2 gene or you have had DCIS or LCIS it may be suggested to do the following:
- Genetic counselling or testing for breast cancer risk.
- Close observation to look for early signs of breast cancer.
- Medicines to lower breast cancer risk.
- Preventive surgery.
Genetic counselling and testing
If there is a possibility that you have an inherited gene change which increases your risk, then genetic counselling is worthwhile.
Close observation
Medicines to lower breast cancers risk:
- Tamoxifen.
- Raloxifene.
- Preventative surgery, but the mainstay for all is screening.
So how do we Screen for Breast Cancer?
The American Cancer Society screening recommendations for women at an average breast cancer risk
For screening purposes, a woman is considered to be at an average risk if she does not have a personal history of breast cancer, a strong family history of breast cancer, or a genetic mutation known to increase risk of breast cancer (such as in a BRCA gene), and has not had chest radiation therapy before the age of 30.
- Women between 40 and 44 have the option to start screening with a mammogram every year.
- Women 45 to 54 should get a mammogram every year.
- Women 55 and older can switch to a mammogram every other year, or they can choose to continue yearly mammograms. Screening should continue as long as a woman is in good health and is expected to live at least 10 more years.
All women should understand what to expect when getting a mammogram for breast cancer screening – what the test can and cannot do.
Clinical breast exams are not recommended for breast cancer screening among average-risk women at any age.
Mammograms
Mammograms are low-dose x-rays of the breasts. Regular mammograms can help find breast cancer at an early stage. They are, however, not perfect and can miss some cancers. In recent years, a new type of mammogram called the digital breast tomosynthesis (commonly known as 3D mammography) has become much more common. This appears to lower the chance of repeat call backs and finds more breast cancers.
Clinical breast self-examination
Research does not show a clear benefit of regular physical breast examination done by either a doctor or by the women themselves. However, women should be familiar with how their breasts normally look and feel, and should report any changes to a healthcare provider right away.
The American Cancer Society screening recommendation for women at high risk
Women who are at high risk for breast cancer based on certain risk factors should get a breast MRI and a mammogram every year, and should typically start at the age of 30. This includes women who:
- Have a lifetime risk of breast cancer of about 20% to 25% or greater, according to risk assessment tools that are based mainly on the family history.
- Have a known BRCA1 and BRCA2 gene mutation based on having had a genetic test.
- Have had a first-degree relative (parent brother, sister or child) with a BRCA1 or BRCA2 gene mutation of not a genetic testing themselves.
- Had radiation therapy to chest when they were between the age of 10 and 30 years.
- Have Li–Fraumeni syndrome, Cowden syndrome or Bannayan-Riley-Ruvalcaba syndrome, or have first-degree relatives with one of these syndromes.
The American Cancer Society recommends against MRI screening for women whose lifetime risk of breast cancer is less than 15%.
If MRI is used, it should be in addition to, not instead of, screening mammography. Any patient within the high-risk group is referred immediately for genetic counselling and breast specialist advice. NICE has produced guidelines for patients with a familial tendency to breast cancer and these patients should be referred immediately for specialist advice.
Here at The London General Practice, our full check follows the American Cancer Society guidelines for breast cancer screening, and the NICE guidelines for those at increased risk. We have close links with the leading specialists and if, during screening, an abnormality is found, the patient is referred immediately.
To learn more about the screening services at The London General Practice please visit our website.