Know the risk factors and their importance
By Maria Hoertz, DO
Ascension Medical Group
Breast cancer casts a long shadow over women of all ages. In 2016, more than 230,000 American women were diagnosed with breast cancer and more than 40,000 died.
These numbers are sobering, yet women need to maintain a realistic sense of the threat. It’s estimated that 12 percent, or one in eight women, will be diagnosed with breast cancer at some time in life. Yet looked at from another perspective: seven of eight women, or 88 percent, will never be diagnosed.
And younger women face far less risk than older women. The risk for women between 40 and 50 years of age is one in 68; between 50 and 60, one in 42; between 60 and 70, one in 28 and over age 70, one in 26.
In addition to gender and age, there are a number of other factors that increase a woman’s risk.
Having a first-degree relative (mother, sister or daughter) diagnosed with breast cancer doubles the risk. More than one first-degree relative with breast cancer increases the risk three- to four- fold. The risk is also increased if the first degree relative was diagnosed before age 50. Despite this increase in risk, only 13 percent of all breast cancers occur in first degree relatives.
Menstrual history. Women who began menstruating early, before age 12, and those who entered menopause late, after age 55, have an increased risk.
Pregnancy history. Giving birth to a first child after age 30 increases risk slightly, as does never giving birth.
A previous diagnosis of breast cancer increases the risk that cancer will develop in the other breast. A biopsy finding of lobular carcinoma in situ (LCIS) or ductal carcinoma in situ (DCIS) also increases risk. Radiation to the chest before age 30 increases breast cancer risk.
Having a BRCA1 or BRCA2 genetic mutation. Between three and eight percent of breast cancers can be attributed to these mutations. Women with BRCA1 mutations have a 55 to 65 percent lifetime risk of breast cancer and a 40 percent lifetime risk of ovarian cancer. For those with BRCA2, the lifetime risk of breast cancer is 45 percent and ovarian cancer, 10 percent. Having dense breasts has also been recently shown to increase the risk of breast cancer four- to six-fold compared with women with less dense breasts. Dense breasts are made up of glandular and connective tissue; those that are less dense have a higher fat composition.
Dense breasts, however, are very common, especially in younger women. Breasts tend to develop a higher fat content as women age. Breast feeding and a higher number of pregnancies are associated with lower breast density.
Overweight and obesity are important risk factors. During the childbearing years most of a woman’s estrogen comes from the ovaries. After menopause, when estrogen production from the ovaries ends, the main source of estrogen is from fatty tissue. The more fat tissue a woman has the more estrogen will be produced, increasing her overall estrogen exposure and risk for breast cancer.
Sedentary lifestyle. A number of studies have shown the benefits of exercise in controlling the risk of breast cancer. Not only does exercise help with weight control, it also improves blood insulin levels, which are believed to be linked to breast cancer.
Alcohol consumption. One five-ounce drink per day creates a small additional risk. Drinking between 1 ½ and five alcoholic drinks per day can increase the risk to 1 ½ times that of a woman who does not drink alcohol.
Hormone therapy. The use of oral contraceptives raises the risk slightly. So does the use of other hormone-based contraceptives such as Depo-Provera although the risk disappears after five years of no longer getting the shots.
There are a number of protective factors, such as weight control, exercise and breastfeeding that a wide range of women can take advantage of.
Women who face a high risk of breast cancer because of genetic mutations, a strong family history or previous breast cancer or suspicious biopsy results may discuss the possible benefit of taking either tamoxifen or raloxifene (both classed as SERMs–selective estrogen receptor modifiers).
Some women with BRCA1 or BRCA2 mutations opt for surgical removal of their breasts, even when no cancer has been detected. A double mastectomy, which is a major surgical procedure, reduces the risk of breast cancer by 97 percent but does not fully eliminate the risk.
Having one or more risk factors for breast cancer does not mean that a woman will get breast cancer. Sixty percent of women diagnosed with breast cancer have no significant risk factors.
Maria Hoertz, DO is a Family Medicine Physician with Ascension Medical Group. For more information, please visit ascension.org/Wisconsin.