Chemicals in cosmetics, food, and in plastic
There is some concern that exposure to phthalates, specifically, may increase a woman's risk of developing breast cancer, but the data on this issue aren't clear.
Phthalates can be found in medical supplies, food containers, cosmetics, toys, some medications. Aside from this, there is no evidence that exposure to other chemicals increases a woman’s risk of developing breast cancer.
Alcohol consumption has been shown to be associated with an increased risk of breast cancer. Studies indicate that the more alcohol a woman drinks, the higher her risk of developing breast cancer.
This risk factor is not as strong as the risk factors we spoke of before (age, genetics, family history, a history of abnormal breast biopsies, etc.) but alcohol consumption does carry some risk with it.
Smoking is also associated with an increased risk of developing breast cancer, and this association is impacted by when a woman starts smoking and how long she smokes. The earlier a woman starts smoking and the longer she smokes, the more the risk is increased. But again, this is a risk factor that is not as significant as the stronger risk factors.
The risk of breast cancer associated with obesity or an increased body mass index (BMI) differs based on whether a woman is pre- or postmenopausal. Premenopausal women with an increased BMI actually have a lower risk of developing breast cancer. Postmenopausal women with an increased BMI have a higher risk.
The strongest risk factor for breast cancer is age. Therefore, older women are at a higher risk of developing breast cancer than younger women.
However, BMI alone doesn’t tell the whole story because even if a woman has a healthy BMI, it appears that if she has a higher percentage of body fat (so she has a healthy weight but low muscle mass and high body fat), her risk might also be increased. The bottom line is that women should aim to eat as healthy as they can and get regular exercise to keep their body composition at an optimal place for them.
In the United States at least, the risk of breast cancer is highest among white women. However, breast cancer in women who are less than 40 and certain types of breast cancer, such as triple-negative breast cancer, are more common in black women.
A study came out a couple of years ago that showed that oral contraceptives do slightly increase the risk of breast cancer. How much they increase the risk depends on the type of oral contraceptive used, how long the oral contraceptive was used and how recently a woman took the oral contraceptive.
What I tell my patients is: "Yes, although oral contraceptives do appear to slightly increase the risk of breast cancer, for most women the benefits of hormonal contraception outweigh this risk". Each woman must decide for herself what the balance of pros and cons is regarding hormonal contraception. If a very small increased risk of breast cancer is not worth it for a certain individual, then there are non-hormonal forms of contraception that she could consider.
We have always thought that pregnancy was protective in terms of breast cancer risk. However, at the end of 2018 a study came out that pooled the results of multiple studies and showed that there is a small but significant increase in breast cancer risk after pregnancy.
This increased risk peaks at five years and persists for up to 20 years. While this is notable, it is important to remember that the increased risk is still quite low.
Breastfeeding can increase the risk for cancer especially if a woman has breastfed for longer than twelve months. It appears that for every 12-month interval that a woman breastfeeds, her breast cancer risk is slightly reduced.
There is a very rare type of lymphoma that has been associated with certain types of implants, but breast implants have not been found to be associated with the development of breast cancer.
In terms of detecting breast cancer in a woman who has breast implants, the implants are placed behind or deep to the breast tissue, so it is still possible to examine the breast tissue via palpation and imaging with an implant in place. During a mammogram specialized techniques are used to capture images of the breast tissue while not damaging the implants.
Who is most at risk of developing breast cancer?
1. The strongest risk factor for breast cancer is age. Therefore, older women are at a higher risk of developing breast cancer than younger women.
2. Another significant risk factor is carrying a gene that predisposes to the development of breast cancer, such as the BRCA 1 and 2 genes. Related to carrying a gene that causes breast cancer, having a strong family history of breast cancer also increases a person’s risk. Women who carry a gene that causes breast cancer or women who have a strong family history of breast cancer are at higher risk than women who do not.
3. Another risk factor for breast cancer is having a history of a breast biopsy that showed atypical cells, such as atypical ductal hyperplasia or lobular carcinoma in situ.
4. Lastly, there are several risk factors associated with a woman's exposure to hormones (i.e. estrogen) throughout her lifetime, such as early menarche, number of pregnancies, whether or not a woman has breastfed, late menopause, that impact breast cancer risk. The more a woman has been exposed to estrogen and the more menstrual cycles she has experienced, the higher her risk of developing breast cancer.