The main risk factors of cancer are currently known; however, the precise causes of breast cancer can still be unclear. Two of the most significant factors include family history and age. Risk also increases for women who have certain types of benign breast lumps or who have previously had ovarian cancer or breast cancer.
Higher risk, however, does not always mean an individual will develop the disease; some women with no known risk factors develop cancer while others with a high risk remain cancer-free.
The genes BRCA1 and BRCA2, sometimes referred to as “faulty genes,” have recently been identified as responsible for some instances of familial breast cancer. These genes, carried by about one in 200 women, predispose a woman to the disease.
If a woman’s first-degree relative (such as a mother, sister, or daughter) has breast cancer, her risk is two to three times higher than a woman for whom this is not the case. Women over 50 are also more likely to get breast cancer than are younger women, and African-American women are more likely than Caucasians to get breast cancer before entering menopause.
Researchers have also examined the link between diet and breast cancer. Though it remains somewhat debated, obesity and drinking alcohol regularly are traits that are suspected to promote the disease. Less debated is the role that fat plays in breast cancer risk; in fact, numerous studies have found a link between breast cancer and diets high in fat. Most researchers recommend lowering one’s daily calories from fat to less than 20-30% as a protective measure against breast cancer.
Hormones and Risk
In addition to these factors, a clear link between cancer and hormones has begun to establish itself, more specifically, the hormone estrogen. Since estrogen prompts the division of cells, it increases the likelihood of an abnormality. There abnormalities can possibly become cancerous.
A woman’s estrogen and progesterone levels rise and fall during her lifetime, influenced by a variety of factors, such as her age of first and last menstrual cycle, her age at first childbirth, and the length of her average menstrual cycle. A woman’s risk is decreased if she has her first period after age 12, stops menstruating before age 55, and has a cycle that is within the average range of 26-29 days.
No studies have indicated that the hormones in birth control pills significantly increase the risk, which has come as a relief to many women. Unfortunately, taking hormone replacement therapy after menopause may increase the risk, especially if a woman takes it for over five years. Radiation therapy can also have a negative effect when applied in heavy doses; however, lose-dose mammograms pose next to no risk.