Health Tips

Risk factors

A risk factor is anything that makes it more likely you'll get a particular disease. Some risk factors, such as your age, sex and family history, can't be changed, whereas others, including weight, smoking and a poor diet, are under your control.

But having one or even several risk factors doesn't necessarily mean you'll develop cancer — most women with breast cancer have no known risk factors other than simply being women. In fact, being female is the single greatest risk factor for breast cancer. Although men can develop the disease, it's far more common in women.

Other factors that may make you more susceptible to breast cancer include:

• Age. Your chances of developing breast cancer increase with age. Close to 80 percent of breast cancers occur in women older than age 50. In your 30s, you have a one in 233 chance of developing breast cancer. By age 85, your chance is one in eight.
• A personal history of breast cancer. If you've had breast cancer in one breast, you have an increased risk of developing cancer in the other breast.
• Family history. If you have a mother, sister or daughter with breast or ovarian cancer or both, or a male relative with breast cancer, you have a greater chance of also developing breast cancer. In general, the more relatives you have who were diagnosed with breast cancer before reaching menopause, the higher your own risk. If you have one first-degree relative — a mother, sister or daughter — who was diagnosed with the disease before age 50, your risk is doubled. If you have two or more relatives, your risk increases even more. Just because you have a family history of breast cancer doesn't mean it's hereditary, though. Most people with a family history of breast cancer (familial breast cancer risk) haven't inherited a defective gene, such as BRCA1 or BRCA2. Rather, cancer becomes so common in women who live into their 80s and beyond that random, noninherited breast tumors may appear in more than one member of a single family.
• Genetic predisposition. Between 5 percent and 10 percent of breast cancers are inherited. Defects in one of several genes, especially BRCA1 or BRCA2, put you at greater risk of developing breast, ovarian and colon cancers. Usually these genes help prevent cancer by making proteins that keep cells from growing abnormally. But if they have a mutation, the genes aren't as effective at protecting you from cancer.
• Radiation exposure. If you received radiation treatments to your chest as a child or young adult, you're more likely to develop breast cancer later in life. Your risk is greatest if you received radiation as an adolescent during breast development.
• Excess weight. The relationship between excess weight and breast cancer is complex. In general, weighing more than is healthy increases your risk, particularly if you gained the weight as an adolescent. But risk is even greater if you put the weight on after menopause. Your risk also is greater if you have more body fat in the upper part of your body.
• Early onset of menstrual cycles. If you got your period at a young age, especially before age 12, you may have a greater likelihood of developing breast cancer. Experts attribute this risk to the early exposure of the breast tissue to estrogen.
• Late menopause. If you enter menopause after age 55, you're more likely to develop breast cancer. Experts attribute this to the prolonged exposure of the breast tissue to estrogen.
• First pregnancy at older age. If your first full-term pregnancy occurs after age 30, or you never become pregnant, you have a greater chance of developing breast cancer. Although it's not entirely clear why, an early first pregnancy may protect breast tissue from developing genetic mutations that result from estrogen exposure.
• Race. White women are more likely to develop breast cancer than black, Hispanic or Asian women are, but black women are more likely to die of the disease because their cancers are found at a more advanced stage. Although some studies show that black women may have more aggressive tumors, it's also likely that the disparity is at least partially due to socioeconomic factors. Women of all races with incomes below the poverty level are more often diagnosed with late-stage breast cancer and more likely to die of the disease than are women with higher incomes. Low-income women often don't receive the routine medical care that would allow breast cancer to be discovered earlier.
• Hormone therapy. Treating menopausal symptoms with the hormone combination of estrogen and progesterone for four or more years increases your risk of breast cancer. In addition, therapy with estrogen and progesterone can make malignant tumors harder to detect on mammograms, leading to cancers that are diagnosed at more advanced stages and that are harder to treat. Using estrogen alone hasn't been shown to increase breast cancer risk in postmenopausal women.
• Birth control pills. Use of birth control pills is associated with an increased risk of breast cancer in premenopausal women. The risk seems to be greater for women who use birth control pills for four or more years before their first full-term pregnancy, but since delayed first pregnancy is also a risk factor, part of the risk could be attributed to that. Overall, risk of breast cancer for users of birth control pills is small and appears to be confined to the short term. Risk levels return to normal within five to 10 years after discontinuing use. Using birth control pills also doesn't appear to further increase breast cancer risk in women with a family history of breast cancer or with a personal history of benign breast disease. Because this is an area of ongoing study, talk with your doctor about the latest information on the pill and breast cancer.
• Smoking. Evidence is mixed on the relationship between smoking and breast cancer risk. Some studies show no link between cigarette smoking and exposure to secondhand smoke and breast cancer. Others suggest that smoking increases breast cancer risk. Exposure to secondhand smoke and breast cancer risk remains an area of active research. Despite the controversy surrounding this issue, there are clear health benefits — other than minimizing breast cancer risk — to quitting smoking and limiting your exposure to secondhand smoke.
• Excessive use of alcohol. According to the American Cancer Society, women who drink more than one alcoholic beverage a day have about a 20 percent greater risk of breast cancer than do women who don't drink. To reduce your breast cancer risk, limit alcohol to no more than one drink daily.
• Precancerous breast changes (atypical hyperplasia, lobular carcinoma in situ). These changes are discovered only after you have a breast biopsy, most commonly done for another reason. If these changes are present, your risk of breast cancer is higher than it is for women who don't have one of these so-called "markers." If you have carcinoma in situ, discuss treatment and monitoring options with your doctor.

• Mammographic breast density. Breasts described as "dense" have a high ratio of connective and glandular tissue to fat. On X-ray images, dense breast tissue looks solid and white, so it can mask tumors and make mammograms difficult to interpret. Increasingly, though, breast density is also being recognized as a breast cancer risk factor in itself. The mechanism behind this increased risk is unknown.

  Your age and menopausal status affect your breast density. Younger women tend to have denser breasts. Hormones also have an effect — higher hormone levels generally mean denser breasts. Still, the actual increase in risk due to mammographic density is very small. If you're at high risk of breast cancer and your mammograms are difficult to interpret because of breast density, your doctor may recommend additional screening tests.