A risk factor is something that increases the likelihood of developing a disease, such as cancer. However, having a risk factor does not mean you will definitely get the disease. While you cannot change some risk factors like family history and age, there are several risk factors you can control.
The main lifestyle risk factors affecting breast cancer include diet and exercise. Other factors include decisions about having children and taking hormone-containing medications. Modifiable breast cancer risk factors include:
1. Alcohol consumption
Alcohol consumption is a very clear factor that increases the risk of breast cancer, with the risk increasing depending on the amount of alcohol consumed. A woman who drinks one alcoholic beverage per day increases her risk of breast cancer by 7-10% compared to non-drinkers, while drinking 2-3 beverages increases the risk by 20%. Alcohol consumption is also associated with an increased risk of other types of cancer.
The American Cancer Society recommends not drinking more than one alcoholic beverage per day.
2. Obesity or Overweight
Obesity or overweight after menopause increases the risk of breast cancer. Before menopause, the ovaries are the organs that produce a lot of estrogen, and fat tissue does not produce much estrogen. After menopause, when the ovaries no longer produce estrogen, most of the estrogen in the body comes from fat tissue. If one is obese, it will increase fat tissue and estrogen levels, raising the risk of breast cancer. At the same time, these individuals will have higher insulin levels in the blood, increasing the risk of several other types of cancer, including breast cancer.
However, the relationship between weight and breast cancer is complex. For example, the risk of breast cancer after menopause is higher in women who gain weight after menopause, whereas before menopause, obese women have a lower incidence of breast cancer compared to other women. The exact reasons for this are not yet known.
Weight also affects different types of breast cancer differently; for instance, obesity is often associated with estrogen receptor-positive breast cancer after menopause, but before menopause, it increases the risk of triple-negative breast cancer.
The American Cancer Society recommends that women maintain a healthy weight and balance their diet and exercise.
3. Lack of exercise
There is evidence that physical activity reduces breast cancer, especially in premenopausal women. The main question is how much exercise is sufficient. Some studies have found that even just a few hours of exercise per week can be beneficial, although regular exercise is better.
The exact number of hours of exercise is not clearly known, but it can lead to weight loss, reduced inflammation, increased health-protective hormones, and balanced energy levels.
The American Cancer Society recommends that women should have at least 150 minutes of moderate exercise or 75 minutes of vigorous exercise per week.
4. Not breastfeeding
Most studies indicate that breastfeeding reduces the risk of breast cancer, especially when done for a sufficiently long and continuous period. However, it is difficult to study this accurately, particularly in developed countries where the duration of breastfeeding is often not long.
The explanation for this influencing factor may be that breastfeeding reduces the time of menstruation in a woman’s lifetime, similar to having a later onset of menstruation but an earlier cessation.
5. Birth Control
Some birth control methods use hormones, which can have effects such as:
- Oral contraceptives: Most studies find that women who use oral contraceptives have a slightly increased risk of breast cancer compared to those who do not use them. If not used, the risk decreases within 10 years.
- Injectable contraceptives: Depo-Provera is a birth control injection given every 3 months. Some studies have found a slight increase in risk factors, but other studies have not found an increase.
- Implants, skin patches, intrauterine devices: These may use hormones and could increase risk. Some studies indicate that these methods may increase risk, but there are not many studies on this.
6. Use of hormone therapy after menopause
Hormone therapy with estrogen (often combined with progesterone) has been used in recent years to reduce menopausal symptoms and help prevent osteoporosis. This treatment is known by various names such as menopausal hormone therapy, hormone replacement therapy.
There are two main types of hormone therapy, with women who still have a uterus using a combination of estrogen and progestogen (HT) because estrogen alone can cause uterine cancer. In cases where the uterus has been removed, only estrogen (ET) is needed.
- HT: Increases the risk of breast cancer, often rising after 4 years of use, typically detecting invasive breast cancer, and often shows a reduced risk within 5 years of not using this treatment.
- ET: Studies on the use of estrogen alone after menopause yield differing results; some studies indicate a slight increase in risk, while others do not find an increase in breast cancer risk factors.
Up to this point, there is not much scientific evidence supporting the use of hormone therapy during menopause. Hormone therapy not only increases the risk of breast cancer but also raises the risk of cardiovascular disease, blood clotting, and stroke.
The decision to use hormone therapy should be discussed between the patient and their doctor to weigh the pros and cons and the risk factors for cardiovascular disease, breast cancer, and osteoporosis. If the patient decides to use hormone treatment for menopausal symptoms, it should be used at the lowest possible dose.
7. Breast Implants
Breast implants do not pose a risk of breast cancer; however, breast cancer screening in these women needs to be discussed and appropriate methods should be established.
