Epidemiologic studies have identified many risk factors that increase the chance of a woman developing breast cancer. The common denominator for many of these risk factors is their effect on the level and duration of exposure to hormones (estrogens). For example, starting early with menstrual bleedings, no childbirth, and late menopause increase lifetime exposure to estrogen in premenopausal women, whereas obesity and hormone replacement therapy increase estrogen levels in postmenopausal women.
There are things that individuals can do to reduce their risk for cancer. Top of these is tobacco, followed by healthy body weight, avoiding too much sun and alcohol, but there are also several new recommendations – about radon, breast-feeding, and hormone replacement therapy (HRT), and also about vaccinations and organized screening programs.
Age is the most significant risk factor for breast cancer, with breast cancer being rare in women younger than 25 years. Incidence increases with increasing age, with a plateau in women aged 50-55 years. Even a family history of breast cancer in a first-degree relative is the most widely recognized breast cancer risk factor. A family history of ovarian cancer in a first-degree relative, especially if the disease occurred at an early age (< 50 y), has been associated with a doubling of breast cancer risk. Although 20-30% of women with breast cancer have at least one relative with a history of breast cancer, only 5-10% of women with breast cancer have an identifiable genetic disposition.
One of the most widely studied risk factors in breast cancer is the use of hormones in the form of oral contraceptives and hormone replacement therapy. Risk is increased 1.24 times for 10 years’ use, normalizing 10 years after discontinuation. Such factors includes no childbirth, first full pregnancy when older than 30 years, first menstruation when younger than 13 years (2 times the risk), menopause when older than 50 years, and not breastfeeding also increase the risk of breast cancer.
A study found that low levels of alcohol consumption were associated with a small increase in breast cancer risk; cumulative alcohol intake throughout adult life was the most consistent measure. Observational studies suggest that physical activity after a breast cancer diagnosis is associated with improved cancer outcomes. Observational studies suggest that physical activity after a breast cancer diagnosis is associated with a lower risk of breast cancer-specific and all-cause mortality. Some studies also support a dose–response association between physical activity and breast cancer outcomes and suggest possible effect modification by disease stage, body mass index, and estrogen receptor status.
Anything that increases your chance of developing cancer is called a cancer risk factor; anything that decreases your chance of developing cancer is called a cancer protective factor. Some risk factors for cancer can be avoided, but many cannot. For example, both smoking and inheriting certain genes are risk factors for some types of cancer, but only smoking can be avoided. Regular exercise and a healthy diet may be protective factors for some types of cancer.
Avoiding risk factors and increasing protective factors may lower the risk but it does not mean that you will not get cancer. Reducing behavior and routine check-up is the only way to follow.
Dr. Murat Koc
(Gyne Oncology, Obstetrics & Gynecology Consultant)
Bahrain Specialist Hospital