About 70% of breast cancer cases occur without any explicit cause; the tumor just occurs with no apparent reason. However, there are factors clearly identified as obvious risks of breast cancer. Most factors that can increase the risk of breast cancer include:
Age: although breast cancer can affect young women of all ages, its risk increases with age. It is shown that breast cancer is more common among older people. Therefore, if you are aged 45 or older, your risk of developing breast cancer may be about 2 times higher than those in their thirties; if you are between 55 and 64, your risk is about 3 times higher than women in their forties.
Hormone replacement therapy (HRT): according to WHO (World Health Organization),menopause hormone therapy (MHT) is a risk factor for breast cancer especially when taken for more than 5 years. some scientists believe that the risk of developing breast cancer increases by 1% per year by taking estrogen alone and 8% per year if the therapy consist of a combination of estrogen and progesterone. In addition, studies show that hormone therapy can also increase the risk of colon cancer. However, those risks may disappear about 2 years after cessation of the therapy.
Prolonged exposure to endogenous estrogen: in menopause women, this hormone is produced by the body under the action of the adrenal glands. In premenopausal women, it is produced at 60% by the ovaries (estradiol) and 40% by the adrenal glands (estrone). Prolonged exposure to endogenous estrogens may be a risk of breast cancer. It is found a higher rate of breast cancer among women 35 to 65 years old who had their first menstruation early (before age 12 for instance), late menopause, nulliparity (no pregnancy) or late pregnancy.
Family history: your genetic factors to develop breast cancer are about 5-10% if you have close relatives suffering from the disease. Genetic is primarily responsible for breast cancers occurring before age 40. Some genes that appear responsible for developing the disease include BRCA I, a defect on chromosome 17 associated with an increased risk for breast cancer, and inherited by only 1 in 200 women; and BRCA II, defect on chromosome 13 which is associated with an increased risk of ovarian cancer, fallopian tube cancer, prostate cancer, and pancreatic cancer, as well as malignant melanoma. BRCA II is also associated with breast cancer in men.
It is also thought that defects in TSG101 (tumor susceptibility gene 101) may have a role in the development of breast tumor. However, the significance of TSG101 alterations in development of cancer (carcinogenesis) is controversial since aberrant transcripts of TSG101 gene have also been identified in normal non-cancerous tissues.
Ataxia-telangiectasia , a rare neurodegenerative disorder, is another inherited disease suspected to weaken the immune system, leading to respiratory disorders and increased risk of breast cancer.
Nutrition : In addition to its beneficial effect on bone and against chronic pain, vitamin D may play a role in the prevention of the proliferation of cancer cells in women breast. Vitamin A deficiency among female victims of breast cancer seems to contribute to the development of the disease. A group of doctors at Mount Sinai Hospital in Toronto, compared the vitamin D levels of 760 women with breast cancer with those of 1 140 healthy women. The studies have shown that high levels of vitamin D were associated with a decrease of 24% risk of breast cancer.
In the other hand, it is found that soy products, some fatty acids (mostly omega-3), fruits, cruciferous vegetables and all other natural foods that are rich anti-oxidant vitamins can reduce up to 20% the risk of breast cancer. These substances fight against breast cancer by destroying free radicals and blocking the hormone receptors.
Smoking: in addition to pulmonary, oral, head and neck cancers, cigarette smoke can also cause breast cancer. Comparably to non-smoker women, it is shown in many studies that the risk of breast cancer before age 50 is about 70% higher among women who start smoking regularly within five years after the onset of their menstruation.
Alcohol: even moderate consumption of alcohol is causative factor for breast cancer. This risk increases by 9% for each glass of alcohol consumed daily. Contribution of alcohol in the development of breast cancer is mostly in pre-menopausal women and also in postmenopausal women who take hormone replacement.
X-rays and mammography: the modern mammography equipment delivers very little radiation compared to what existed 15-20 years ago, which lowers considerably its carcinogenic potentiality. However, the risk of breast cancer exists for women under 30 years due to glandular susceptibility and the fact women at these ages require greater amount of radiation for imaging of their breasts. Therefore, repeated mammography can increase the risk of breast cancer in young women.
Puberty and menopause – An early puberty and late menopause can increase the susceptibility to be affected by breast cancer. A woman whose menopause happens naturally after age 55 has more chances to have breast cancer than a woman who has her menopause before age 45.
Pregnancy – the absence of pregnancy can increase the chances of breast cancer. In addition, if you have your first pregnancy in your thirties, you have two times more likely chance to develop breast cancer over a woman who becomes a mother in her early twenties. The risk is even higher if you have no children.
Breastfeeding – although some women do not like it, breastfeeding plays a key role in preventing breast cancer. Studies have showed that prolonged breastfeeding reduces considerably the risk of developing breast cancer. In addition, it provides many benefits in the physical and mental development of the infant. By breastfeeding you increase the chance of your infant to be healthy, and decrease your risk of developing breast cancer.