Breast Cancer - Risk Factors

Breast cancer is the most common cancer and it causes most deaths among women. Understanding the risk factors helps us to identify women most likely to have cancer and reduce its incidence.

It is not known exactly why breast cancer arises, but some factors that favor its development have been identified.

It is good to note that when we talk about risk factors, we refer to situations that increase the likelihood of cancer emergence. Women with risk factors do not necessarily come to have cancer as well as the absence of risk factors does not eliminate the chance of having it. Obviously, the more risk factors a person has, the greater their chances of developing a certain disease.

In the specific case of breast cancer about 70% of patients do not present a clearly identifiable risk factor. But when comparing women with risk factors and women without risk factors, the incidence of cancer is clearly higher in the first group.

Breast cancer
Breast cancer

Risk factors for breast cancer that cannot be changed

1. Female
This is kind of obvious. Women are 100 times more likely to get breast cancer than men. In the U.S. each year nearly 200,000 new cases of breast cancer are diagnosed in women compared with only 2,000 in men.

2. Age
The risk of breast cancer increases sharply from 45 years of age, reaching its peak around 65-70 years. About 77% of women with breast cancer are older than 50.

While the risk of breast cancer in women of 30 is only 1 in 2000 women, at 75 the risk is 1 in 10.

3. Ethnicity
White (Caucasian) is the ethnic group with the highest incidence of breast cancer. Blacks have a slightly lower risk, but their mortality is higher due to more aggressive tumors and the fact that these people are poorer and have less access to early diagnosis means. Hispanics and Asians have about 30% less risk of breast cancer than whites.

4. Family history
Having a first-degree relative with breast cancer increases the risk of having it at 1.8 times. Having two first-degree relatives with breast cancer increases the risk by 2.9 times. If you have a first-degree relative diagnosed with breast cancer before age 40, then your risk of also having it before 40 increases by 5.7 times.

However, despite these data, only 15% of women with breast cancer have a positive family history. The other 85% of cases occur in women with no family history.

Family history is also important to identify some genetic mutations that favor the emergence of breast cancer. When several family members have the disease, we are probably dealing with a family that has mutations in the genes BRCA1 and BRCA2. Women with these altered genes have a 65% chance that they will get breast cancer until the age of 70.

The BRCA 1 and BRCA 2 are responsible for around 5% of all breast cancers. Therefore, the vast majority of cases are not related to these mutations.

5. Personal history of breast cancer
Anyone who has had breast cancer once, has 4 times higher risk of having a second breast cancer, either in the same or other breast. Warning: a new breast cancer recurrence is referred here, not the first.

6. Benign breast lesions
Most benign breast lesions do not lead to a greater risk of breast cancer. Among them we can mention simple fibroadenoma, fibrocystic changes, papilloma and ductal ectasia. However, some lesions such as atypical ductal hyperplasia and atypical lobular hyperplasia are recognized as risk factors, about 5 times increasing the risk of breast cancer.

7. Age at menarche (first menstruation) and menopause
Women with early menarche (before the age of 12) and / or late menopause (after the age of 55) have a higher risk of breast cancer.

8. Radiation in the chest region
People with a history of cancer undergoing radiotherapy of the chest, as in the treatment of lymphoma, people exposed to radiation as atomic bomb survivors or people who contacted with radioactive material, such as nuclear power plant accidents, have a higher risk of breast cancer. This risk is even greater if the exposure occurred during youth.

9. Height
Not sure why, but taller women have higher risk of breast cancer. Women over 1.75 m have 20% more risk than women under 1.60 m.

10. Density of breasts
Women with denser breasts have a higher risk of breast cancer and greater difficulty in diagnosing it by mammography. Warning: breast density does not necessarily have to do with its size.

Risk factors for breast cancer that can be changed

Changeable risk factors
Changeable risk factors
1. Age of first child and number of children
Women who have their first child earlier have a lower risk of breast cancer compared to women who give birth only after 30 years of age. Women with their first child before the age of 20 have fewer risks than women with their first child at 25, which in turn have lower risk than women with first birth after 30.

Women over 40 who have never had children are at greatest risk, about 30% more than women with children. It is estimated that each child reduces risk of breast cancer by 7%.

2. Breastfeeding
Breastfeeding reduces the risk of breast cancer: each 12 months of lactation lowers the risk by 4.3%. Women with large offsprings and long duration of breastfeeding are more protected.

3 Birth control pills
There is controversy about the influence of contraceptives on breast cancer. Currently it is accepted that there is a small increase in risk, which disappears after discontinuation. However, there is a group of experts who disputes the methodology of studies that show this relationship. The fact is that even if there is an increased risk, it is small.

4. Hormone replacement therapy
The hormone replacement therapy, especially that combines estrogen with progestin, is associated with an increased risk of breast cancer. This effect, however, only occurs when it is used more than 2-3 years.

5. Obesity
The higher is the fat tissue, the greater is the risk of breast cancer. Women with a BMI greater than 33 kg/m2 (obesity) have 27% more risk than women with normal BMI. This risk is further increased in women after menopause.

6. Drinking
Alcohol consumption increases the risk of breast cancer. The higher is the intake, the greater is the risk. Alcohol also appears to potentiate the risk of hormone replacement therapy.

7. Physical activity
Exercise decreases the risk of breast cancer, independent of its effect on weight reduction. Even 40 minutes walk 3 times a week is enough to reduce the risk. Women, who exercise more intensely, as up to 10 hours a week of walking or running, have even up to 40% less chance of developing breast cancer.

The American Society of Oncology recommends 45 minutes of daily exercise for at least 5 days a week.

8. Night work
Women working in night shifts have a higher risk of breast cancer. This probably occurs by alterations in circadian secretion of hormones such as melatonin, which normally occurs during the early morning but which is inhibited by artificial light.

Myths about risks for breast cancer

1. Use of bra
Contrary to what has lately run by Internet e-mails, there is no scientific evidence that the use of bra increases the risk of breast cancer. Indeed, the only study that showed a slight elevation of risk presented a methodological flaw, since the number of obese women with dense breasts and known risk factors, who wore a bra was bigger than lean women.

There is also a book called "Dressed to Kill" by Sydney Ross Singer and Soma Grismaijer hypothesizing that bra cause breast cancer. This book is based on theories and there are no published scientific studies that prove it.

So in light of current scientific knowledge, it can be stated that the bra does not cause breast cancer.

2. Abortion
Both induced abortion and miscarriage do not increase the risk of breast cancer.

3. Antiperspirant deodorant
More rumors were raised by one of the current e-mail. There is no scientific basis and theory behind the myth is flawed because the body does not eliminate toxins through sweat. Our sweat compound is only 99% of water and mineral salts. It is the kidneys and liver that remove toxins in our body. Therefore, deodorants do not cause breast cancer.

4. Silicone breast implants
Silicone implants do not increase the risk of breast cancer, but they can create scarring and hinder the visualization of tumors by mammography, and is often necessary to perform additional impact on radiographs.

5. Caffeine
There are no studies attesting any relationship between caffeine consumption and breast cancer.

6. Routine mammograms
Another common rumor is that exposure to radiation in mammograms performed annually can increase the risk of breast cancer. This is also a myth since the radiation used in each test is extremely low. In fact, annually we receive approximately twice as more radiation of chest only by natural sunlight.

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User discussion

28 February 2013
The bra/cancer link is NOT a myth. Several studies show a major link. You should not call this a myth without evidence showing it is false.
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