INTRODUCTION:

A risk factor is anything that increases your chances of getting a disease, such as cancer. But having a risk factor, or even many, does not mean that we are sure to get the disease! While we can’t change some breast cancer risk factors—family history and aging, for example—there are some risk factors that we can control¹Certain breast cancer risk factors are related to personal behaviors, such as diet and exercise. Other lifestyle-related risk factors include decisions about having children and taking medicines that contain hormones.¹

1. Nonmodifiable Risk Factors:

Some risk factors for breast cancer are things we cannot change, such as getting older or inheriting certain gene changes. These make your risk of breast cancer higher. Being born female Men can get breast cancer, too, but this disease is much more common in women than in men.

Getting older As get older, risk of breast cancer goes up. Most breast cancers are found in women age 55 and older.⁷

Inheriting certain gene changes:

About 5% to 10% of breast cancer cases are thought to be hereditary, meaning that they result directly from gene changes (mutations) passed on from a parent.

BRCA1 and BRCA2: The most common cause of hereditary breast cancer 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.⁸

· 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.

Other genes: Other gene mutations 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 (or helps kill the cell if the damaged can't be fixed). Inheriting 2 abnormal copies of this gene causes the disease ataxia-telangiectasia. Inheriting one abnormal copy of this gene has been linked to a high rate of breast cancer in some families.

· TP53: The TP53 gene helps stop the growth of cells with damaged DNA. Inherited mutations of this gene cause Li-Fraumeni syndrome. People with this syndrome have an increased risk of breast cancer, as well as some other cancers such as leukemia, brain tumors, and sarcomas (cancers of bones or connective tissue). This mutation is a rare cause of breast cancer.

· CHEK2: The CHEK2 gene is another gene that normally helps with DNA repair. A CHEK2 mutation increases breast cancer risk.

· PTEN: The PTEN gene normally helps regulate cell growth. Inherited mutations in this gene can cause Cowden syndrome, a rare disorder that puts people at higher risk for both cancer and benign (non-cancer) tumors in the breasts, 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 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 (abnormal growths) 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 also been linked to breast cancer, but these account for only a small number of cases.(1)

Having a family history of 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 (mother, sister, or daughter) with breast cancer almost doubles a woman’s risk. Having 2 first-degree relatives increases her risk about 3-fold.

· 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 this disease.²

Having a 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.⁸

Race and ethnicity. Breast cancer is the most common cancer diagnosis in women, other than skin cancer, regardless of race. White women are more likely to develop breast cancer than Black women, but among women younger than 45, the disease is more common in Black women than in white women. Black women are also more likely to die from the disease. Reasons for survival differences may include differences in biology, other health conditions, and socioeconomic factors affecting access to, and use of, medical care.²

Being taller 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.

Having dense breast tissue:

Breasts are made up of 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 breast tissue can also make it harder to see cancers on mammograms.

A number of factors can affect breast density, such as age, menopausal status, the use of certain drugs (including menopausal hormone therapy), pregnancy, and genetics.²

Having certain benign breast conditions:

Women diagnosed with certain benign (non-cancer) breast conditions may have a higher risk of breast cancer. Some of these conditions are more closely linked to breast cancer risk than others. Doctors often divide benign breast conditions into 3 groups, depending on how they affect this risk.

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 or disease), Mild hyperplasia, Adenosis (non-sclerosing), Phyllodes tumor (benign), A single papilloma, Fat necrosis, Duct ectasia, Periductal fibrosis, Squamous and apocrine metaplasia, Epithelial-related calcifications, Other tumors (lipoma, hamartoma, hemangioma, neurofibroma, adenomyoepithelioma).

Proliferative lesions without atypia (cell abnormalities):

In these conditions there’s 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 (without atypia), Fibroadenoma, Sclerosing adenosis, Several papillomas (called papillomatosis), Radial scar

Proliferative lesions with atypia:

In these conditions, the cells in the ducts or lobules of the breast tissue grow excessively, and some of them no longer look normal. These types of lesions include:, Atypical ductal hyperplasia (ADH), Atypical lobular hyperplasia (ALH)

Breast cancer risk is about 4 to 5 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 (become invasive breast cancer) 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).²

Starting menstrual periods early Women who have had more menstrual cycles because they started menstruating early (especially before age 12) have a slightly higher risk of breast cancer. The increase in risk may be due to a longer lifetime exposure to the hormones estrogen and progesterone.

Going through menopause after age 55 Women who have had more menstrual cycles because they went through menopause later (after age 55) have a slightly higher risk of breast cancer. The increase in risk may be because they have a longer lifetime exposure to the hormones estrogen and progesterone.

Having radiation to your chest Women who were treated with radiation therapy to the chest for another cancer (such as Hodgkin or non-Hodgkin lymphoma) when they were younger have a significantly higher risk for breast cancer. This risk depends on their age when they got radiation. The risk is highest for women who had radiation as a teen or young adult, when the breasts are still developing. Radiation treatment in older women (after about age 40 to 45) does not seem to increase breast cancer risk.

Exposure to diethylstilbestrol (DES) From the 1940s through the early 1970s some pregnant women were given an estrogen-like drug called DES because it was thought to lower their chances of losing the baby (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.¹

2. Lifestyle-related or Modifiable Breast Cancer Risk Factors:

Certain breast cancer risk factors are related to personal behaviours, such as diet and exercise. Other lifestyle-related risk factors include decisions about having children and taking medicines that contain hormones.

Drinking 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.

It is best not to drink alcohol. For women who do drink, they should have no more than 1 drink a day.

Being overweight or obese:

Being overweight or obese after menopause increases breast cancer risk. Before menopause your ovaries make most of your estrogen, and fat tissue makes only a small part of the total amount. After menopause (when the ovaries stop making estrogen), most of a woman’s estrogen comes from fat tissue. Having more fat tissue after menopause can raise estrogen 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.¹

Still, the link between weight and breast cancer risk is complex.

For instance, the risk of breast cancer after menopause is higher for women who gained weight as an adult, but the risk before menopause is actually lower in women who are obese. The reasons for this aren’t exactly clear.

Higher birth weight has a relationship with increased risk of BC in premenopausal women, particularly when birth weight is above 3.5 kg⁶.

Not being physically active:

Evidence is growing that regular physical activity reduces breast cancer risk, especially in women past menopause. The main question is how much activity is needed. Some studies have found that even as little as a couple of hours a week might be helpful, although more seems to be better. It may be due to its effects on body weight, inflammation, hormones, and energy balance.

The American Cancer Society recommends that adults get 150 to 300 minutes of moderate intensity or 75 to 150 minutes of vigorous intensity activity each week (or a combination of these). Getting to or going over the upper limit of 300 minutes is ideal.¹

Not having children:

Women who have not had children or who had their first child after age 30 have a slightly higher breast cancer risk overall. Having many pregnancies and becoming pregnant at an early age reduces breast cancer risk.⁵

Not breastfeeding:

Most studies suggest that breastfeeding may slightly lower breast cancer risk, especially if it’s continued for a year or more.The explanation for this possible effect may be that breastfeeding reduces a woman’s total number of lifetime menstrual cycles (the same as starting menstrual periods at a later age or going through early menopause).

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 (birth control pills) 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.

Birth control shot: Depo-Provera is an injectable form of progesterone that’s given once every 3 months for birth control. Some studies have found that women currently using birth-control shots seem to have an increase in breast cancer risk, but other studies have not found an increased risk.

Birth control implants, intrauterine devices (IUDs), skin patches, vaginal rings: These forms of birth control also use hormones, which in theory could fuel breast cancer growth. 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.

Hormone therapy after menopause:

Hormone therapy with estrogen (often combined with progesterone) has been used for many years to help relieve symptoms of menopause and help prevent osteoporosis (thinning of the bones). This treatment goes by many names, such as post-menopausal hormone therapy (PHT), hormone replacement therapy (HRT), and menopausal hormone therapy (MHT).

There are 2 main types of hormone therapy. For women who still have a uterus (womb), doctors generally prescribe estrogen and progesterone (known as combined hormone therapy, or just HT). Progesterone is needed because estrogen alone can increase the risk of cancer of the uterus. For women who’ve had a hysterectomy (who no longer have a uterus), estrogen alone can be used. This is known as estrogen replacement therapy (ERT) or just estrogen therapy (ET).

Combined hormone therapy (HT): Use of combined hormone therapy after menopause increases the risk of breast cancer. This increase in risk is typically seen after about 4 years of use. Combined HT also increases the likelihood that the cancer may be found at a more advanced stage.

The increased risk from combined HT appears to apply mainly to current and recent users. A woman’s breast cancer risk seems to go back down within 5 years of stopping treatment.

Bioidentical hormone therapy:

The word bioidentical is sometimes used to describe versions of estrogen and progesterone with the same chemical structure as those found naturally in people (as opposed to the slightly different versions found in most medicines). The use of these hormones has been marketed as a safe way to treat the symptoms of menopause. But because there aren’t many studies comparing “bioidentical” or “natural” hormones to synthetic versions of hormones, there’s no proof that they’re safer or more effective. More studies are needed to know for sure. Until then, the use of these bioidentical hormones should be considered to have the same health risks as any other type of hormone therapy.

Estrogen therapy (ET):

Studies of the use of estrogen alone after menopause have had mixed results, with some finding a slightly higher risk and some finding no increase. If ET does increase the risk of breast cancer, it is not by much.

Radiation exposure at a young age. Exposure to ionizing radiation at a young age may increase a woman’s risk of breast cancer. For example, therapeutic radiation to the chest for Hodgkin lymphoma may increase breast cancer risk in both breasts.The very small amount of radiation a woman receives during a mammogram has not been linked to an increased risk of breast cancer.

Breast implants:

Breast implants have not been linked with an increased risk of the most common types of breast cancer. However, they have been linked to a rare type of non-Hodgkin lymphoma called breast implant-associated anaplastic large cell lymphoma (BIA-ALCL), 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 BIA-ALCL does occur after an implant, it can show up as a lump, a collection of fluid, swelling, or pain near the implant, or as a change in a breast’s size or shape.¹

3. Factors with Unclear Effects on Breast Cancer Risk:

There are many factors that research has shown are not linked to breast cancer. You may see information online or hear about these disproven or controversial risk factors, but it's important to learn the facts

Diet and vitamins:

While being overweight or obese and not being physically active have been linked to breast cancer risk, the possible link between diet and breast cancer risk is less clear. Results of some studies have shown that diet may play a role, while others have not found that diet influences breast cancer risk.

Studies of women in the United States have not found a consistent link between high-fat diets and getting breast cancer, although some studies have found a possible link between high-fat diets and a higher risk of dying from breast cancer. Studies have also found 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. Researchers are still not sure how to explain this. Studies comparing diet and breast cancer risk in different countries are complicated by other differences (such as activity level, intake of other nutrients, and genetic factors) that might also affect breast cancer risk.

We do know that high-fat diets can lead to being overweight or obese, which is a known breast cancer risk factor. A diet high in fat is also a risk factor for some other types of cancer. And intake of certain types of fat is clearly linked to a higher risk of heart disease.

Some studies have also suggested that dietary patterns that include vegetables as well as fruits, legumes, lean protein and whole grains may contribute to a reduction in the risk of breast cancer. Dietary patterns high in saturated fats and red and processed meats as well as added sugars, fried foods and refined grains may be breast cancer promoting.⁵

Several studies looking at women in Asian countries have found that diets high in soy products might lower breast cancer risk. But this link has not been 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.

Studies looking at vitamin levels in the body have had inconsistent results. So far, there’s no strong evidence that taking vitamins (or any other type of dietary supplement) reduces the risk of breast cancer.

Chemicals in the environment A great deal of research has been reported and more is being done to understand possible environmental influences on breast cancer risk.

Evidence continues grow that exposure to certain toxins, called endocrine disruptors, can raise your risk of breast cancer. These synthetic chemicals accumulate in fat cells, where they mimic your own natural estrogen, potentially leading to tumor growth. For example, substances found in some plastics, certain cosmetics and personal care products, pesticides, and PCBs (polychlorinated biphenyls) seem to have such properties. In theory, these could affect breast cancer risk.

At this time research does not show a clear link between breast cancer risk and exposure to these substances, but studying such effects in humans is hard to do. More research is needed to better define the possible health effects of these substances and others like them. (1)

Tobacco smoke:

Some studies have found that heavy smoking over a long time might be linked to a slightly higher risk of breast cancer. In some studies, the risk has been highest in certain groups, such as women who started smoking before they had their first child. The 2014 US Surgeon General’s report on smoking concluded that there is “suggestive but not sufficient” evidence that smoking increases the risk of breast cancer.

Researchers are also looking at whether second hand smoke increases the risk of breast cancer. Both mainstream and secondhand smoke contain chemicals that, in high concentrations, cause breast cancer in rodents. Studies have shown that chemicals in tobacco smoke reach breast tissue and are found in breast milk of rodents. In human studies, the evidence on secondhand smoke and breast cancer risk is not clear. Most studies have not found a link, but some studies have suggested it may increase risk, particularly in premenopausal women. The 2014 US Surgeon General’s report concluded that there is “suggestive but not sufficient” evidence of a link at this point. In any case, this possible link to breast cancer is yet another reason to avoid secondhand smoke.⁴

Night shift work Several studies have suggested that women who work at night, such as nurses on a night shift, might have an increased risk of breast cancer. This is an active area of research. Some researchers think the effect may be due to changes in levels of melatonin, a hormone that’s affected by the body’s exposure to light, but other hormones are also being studied.

4. Disproven or Controversial Breast Cancer Risk Factors:

Antiperspirants Internet and e-mail rumors have suggested that chemicals in underarm antiperspirants are absorbed through the skin, interfere with lymph circulation, and cause toxins to build up in the breast, eventually leading to breast cancer.Based on the available evidence (including what we know about how the body works), there is little if any reason to believe that antiperspirants increase the risk of breast cancer.

Bras - There is no good scientific or clinical basis for this claim, and a 2014 study of more than 1,500 women found no association between wearing a bra and breast cancer risk.

Induced abortion - Several studies have provided very strong data that neither induced abortions nor spontaneous abortions (miscarriages) have an overall effect on the risk of breast cancer. For more detailed information.¹

5. For women at increased risk of breast cancer:

If a woman at increased risk for breast cancer (for instance, because woman have a strong family history of breast cancer, a known gene mutation that increases breast cancer risk, such as in the BRCA1 or BRCA2 gene, or one have had DCIS or LCIS), there are some things that might help lower chances of developing breast cancer (or help find it early).

Genetic counseling and testing:

Genetic testing can be done to look for inherited mutations in the BRCA1 and BRCA2 genes (or less commonly in genes such as PTEN, TP53, or others mentioned above). This might be an option for some women who have been diagnosed with breast cancer, as well as for certain women with factors that put them at higher risk for breast cancer, such as a strong family history. While testing can be helpful in some cases, not every woman needs to be tested, and the pros and cons need to be considered carefully. To learn more, see Genetic Counseling and Testing for Breast Cancer Risk.⁸

Close observation:

For women at increased breast cancer risk who don’t want to take medicines or have surgery, some doctors might recommend close observation. This approach might include:

· More frequent doctor visits (such as every 6 to 12 months) for breast exams and ongoing risk assessment

· Starting breast cancer screening with yearly mammograms at an earlier age

· Possibly adding another screening test, such as breast MRI

While this approach doesn’t lower breast cancer risk, it might help find it early, when it’s likely to be easier to treat.³

Medicines to lower breast cancer risk:

Prescription medicines can be used to help lower breast cancer risk in certain women at increased risk of breast cancer.

Medicines such as tamoxifen and raloxifene block the action of estrogen in breast tissue. Tamoxifen might be an option even if you haven’t gone through menopause, while raloxifene is only used for women who have gone through menopause. Other drugs, called aromatase inhibitors, might also be an option for women past menopause. All of these medicines can also have side effects, so it’s important to understand the possible benefits and risks of taking one of them.²

Preventive surgery for women with very high breast cancer risk:

For the small fraction of women who have a very high risk for breast cancer, such as from a BRCA gene mutation, surgery to remove the breasts (prophylactic mastectomy) may be an option. Another option might be to remove the ovaries, which are the main source of estrogen in the body. While surgery can lower the risk of breast cancer, it can’t eliminate it completely, and it can have its own side effects.²

REFERENCES:

1. https://www.cancer.org/cancer/breast-cancer/risk-and-prevention.html

2. https://www.cancer.net/cancer-types/breast-cancer/risk-factors-and-prevention

3. Randolph E.Gross Breast cancer: Risk factors, screening, and prevention Seminars in Oncology Nursing Volume 16, Issue 3, August 2000, Pages 176-184

4. Xue F, Willett WC, Rosner BA, Hankinson SE, Michels KB. (2008) Cigarette smoking and the incidence of breast cancer. Arch Intern Med. 2011 Jan 24;171(2):125-33 https://www.ncbi.nlm.nih.gov/pubmed/21263102

5. Akhila Dandamudi, JessieTommie, Laurie Nommsen-Rivers and Sarah Couch, Anticancer Research June 2018, 38 (6) 3209-3222; DOI: https://doi.org/10.21873/anticanres.12586

6. Wen Zhou, Xu Chen, Hui Huang, Shaoxia Liu, Aixian Xie, Liqin Lan, Birth Weight and Incidence of Breast Cancer: Dose-Response Meta-analysis of Prospective Studies, Clinical Breast Cancer, May 10, 2020 DOI:https://doi.org/10.1016/j.clbc.2020.04.011

7. https://www.cdc.gov/cancer/breast/basic_info/risk_factors.htm

8. Yi-Sheng, Sun,Zhao Zhao, Zhang-Nv Yang, Fang Xu Risk Factors and Preventions of Breast Cancer

9. November 2017International Journal of Biological Sciences 13(11):1387-1397

Received on 09.12.2021 Modified on 07.03.2022

Int. J. Nur. Edu. and Research. 2022; 10(3):276-282.

DOI: 10.52711/2454-2660.2022.00065