Lifetime risk for developing breast cancer, and other risk factors
The single most significant factor influencing the risk of developing breast cancer is age.
Women in their 30’s and younger have very little risk of developing breast cancer, but once a woman hits 40 the risk begins to increase rapidly.
This is the main reason breast cancer screening is usually suggested every year to 18 months for women 40 and over.
But in general terms, based on a life expectancy of 85 years, the cumulative risk for breast cancer development for all women is thought to be approximately 1 in 8.
I have created a new page with more up-to-date information on Lifetime Risks For Developing Breast Cancer. However, this page is still extremely convenient. I would still use it.
Approximate risk of breast cancer by increasing age group
For women at 30, the rate of breast cancer development is about 1 in 2000. When a woman reaches 40 years of age that risk increases to about 1 in 233, and this is taken as a baseline in determining relative risk ratios from screening indicators.
As women age beyond 40, the risk of breast cancer development increases significantly.
Women in their 50s have a 1 in 53 chance of breast cancer development, while a woman of 60 has a chance of 1 in 22.
For a 70 year old woman the chances are 1 in 13, and for woman 80 years and above, the chances really quite high, at 1 in 9.
So, over the entire course of a woman’s life, it is reasonable to suggest that the chances of developing breast cancer are about 1 in 8.
|Woman’s Age by decade||Cumulative Lifetime risk of breast cancer|
1 in 2000
1 in 233
1 in 53
1 in 22
1 in 13
1 in 9
Overall lifetime risk
1 in 8
Other breast cancer risk factors: menarche, menopause, hormone levels, hormone replacement therapy, breast density, alcohol, BRCA genetic variants, and obesity.
Traditional measures of breast cancer risk include family history, pre-existing conditions, and previous treatments. Research on breast cancer risk is ongoing, and new developments in connection with natural hormone levels, hormone replacement therapies, and breast density are now firmly associated with increased risk.
Other studies point to the age of menarche and menopause, age of first pregnancy, and the number of full term pregnancies as influential in breast cancer risk, and these consideration have primarily to do with naturally-occurring hormone levels, either too high or too low.
Known genetic variants such as BRCA1 and BRCA2 are also proven risk factors. Other general health risk factors include obesity (body mass index), and excessive alcohol consumption. Ethnic and environmental factors may also play a role in breast cancer development.
Breast density is now recognized as a major risk factor for breast cancer. Women who have dense breast tissue are more likely to develop breast cancer than women who do not.
Essentially, a dense breast is one in which there are proportionally larger amounts of glandular and connective tissues than fatty tissues, relative to an average breast. Breast density has nothing to do with breast size, or how they look or feel, and can only be measured by mammography.
The one problem with ‘breast density‘ as a risk factor, is that while it is often found in women who have developed breast cancer, it cannot help distinguish between those who will get breast cancer and those who will not.
Breast Cancer risk factors due to naturally occurring hormones
For all women, hormones released at three unique stages in the life-cycle can have a significant effect on the risk of breast cancer development. These include:
- age of first pregnancy, and number of full term pregnancies
There is now a general medical consensus that the later a women experiences menarche, (menarche is the age when a girl gets her first menstrual period) the lower her risk for subsequent breast cancer development.
A woman whose periods started at age 11 has higher risk than a woman who’s periods started at age 13. The reasons for this are unclear, but it is believed that hormones associated with growth and menstruation have a different biology than those associated with pregnancy.
As a girl matures into a woman, the amount of hormones like estrogen, progesterone, and follicle stimulating hormone is significantly increased. Earlier exposure to these hormones somehow leads to higher risk.
Women who have their first child at a younger age are thought to be at decreased risk for breast cancer. Young mothers will tend to have more children, and the greater the number of full term pregnancies a women has, the lower her risk for breast cancer.
Breast-feeding is also thought to be beneficial. The hormones associated with pregnancy reduce the risk of breast cancer, and the sooner a woman’s breasts feel the effects of these hormones, the better.
Post-menopausal women are at a higher risk for breast cancer development than younger, pre-menopausal women. The significant decline of estrogen and other hormones which happens during menopause is thought to increase risk of breast cancer, as the deterrent effect of these hormones is lost. However, artificial hormone replacement to counter the effects of menopause has not reduced breast cancer risk, but has in fact had the opposite effect.
Hormone replacement therapy: Increased breast cancer risk
There is considerable evidence at present to support the idea that hormone replacement therapy for post-menopausal women increases risk for breast cancer. Women who have taken estrogen of moderate potency are at increased risk for both ductal and lobular breast cancer, while those have taken both estrogen and progestin are at risk for all subtypes of breast cancer, but at a slightly higher risk of developing lobular breast carcinoma. As a result of a statistical increase in breast cancer rates, hormone replacement therapy is less commonly administered, and may be on the way out.
Excessive Alcohol consumption increases breast cancer risk
Excessive alcohol consumption places stress on many of the body’s systems and has long been associated with increased risk for many diseases, including cancer.
However, there appears to be a complex relationship between alcohol consumption and hormone levels and this poses a particular increased risk for breast cancer in women. The combination of alcohol consumption with hormone replacement therapy in older women can wreak havoc on hormonal systems and increase risk of breast carcinoma.
Excessive alcohol consumption in young women has also been demonstrated to have a negative effect on the functioning of estrogen and progestin receptors, which may increase the risk of developing breast cancer.
Occasional alcohol consumption does not increase breast cancer risk
Note however, that occasional, mild use of alcohol does not increase risk for breast cancer. In fact, studies have shown that women who drink alcohol occasionally are at lower risk for developing breast cancer than those who never drink alcohol.
Increased breast cancer risk associated with BRCA variants
Genetic and molecular causes of breast cancer is a topic of current interest in breast cancer research, not only in finding genes that are more likely to promote breast cancer development, but also genetic factors which can influence survival and responses to breast cancer treatments.
However, for some time, it has been known that women with the BRCA gene variants do are at a slightly increased risk for developing breast cancer. BRCA1 is a gene variant found on chromosome 17, while BRCA2 is a variant found on chromosome 13. Between 5% and 10% of breast cancers originate with the BRCA variants.
Women carrying the BRCA gene variants do tend to develop breast cancers at earlier ages, but older women having BRCA positive breast cancers still outnumber younger women.
For women who have the BRCA1 gene there is a lifetime 56-87% risk for developing breast cancer, and the lifetime risk for developing ovarian cancer is about 15-45%. For women carrying the BRCA2 gene the risk is slightly lower, at about 37-85%, and a lifetime risk of 10-20% for ovarian cancer. However, it has been shown that women with the BRCA2 variants are at no increased risk of actually dying from breast cancer; they are just more susceptible for breast cancer development.
Perspectives on Breast Cancer Risk factors
Breast cancer risk factors and related statistics can often cause a great deal of anxiety in women. Keep in perspective that breast cancer is treatable and curable in up to 90% of women who develop the disease.
However, increased education and appropriate modification of behavior can certainly decrease risk of developing breast cancer. The avoidance of hormone enhancing and hormone altering treatments, together with a balanced lifestyle, will unquestionably reduce a woman’s risk.
Everything you need to know about breast cancer risks is listed above. But let’s do a couple Q&A anyhow…
- What are some established risk factors for developing breast cancer? Being female, increasing age, a personal history of breast cancer, a family history of breast cancer, inherited genes that increase cancer risk, radiation exposure, obesity, beginning of your period at a younger age, beginning your period at an older age, having your first child at an older age, having never been pregnant, postmenopausal hormone therapy, drinking alcohol, smoking, having dense breasts, lack of exercise, certain breast changes, and race/ethnicity.
- What are some emerging risks for developing breast cancer? Low of vitamin D levels, light exposure at night, DES (diethylstilbestrol) exposure, eating unhealthy food, exposure to chemicals in cosmetics, exposure to chemicals in food, exposure to chemicals for lawns and gardens, exposure to chemicals in plastic, exposure to chemicals in sunscreen, exposure to chemicals in water, and exposure to chemicals when food is grilled/prepared.
- National Cancer Institute Surveillance, Epidemiology and End Results Program, USA, 1995-1997
- Ma, H. Bernstein, L. Ross, R.K., Ursin, G. Hormone-related risk factors for breast cancer in women under age 50 years by estrogen and progesterone receptor status: results from a casecontrol and a casecase comparison. Breast Cancer Research 2006, 8:R39
- Halls, Steve. B. Breast Cancer Risk Calculator. www.halls.md/breast/risk.htm
- Rosenberg, L. Magnusson, C., Lindstrom, E., Wedren, S., Hall, P., Dickman, P. Menopausal hormone therapy and other breast cancer risk factors in relation to the risk of different histological subtypes of breast cancer: a case-control study.Breast Cancer Research 2006, 8:R 11.
- Barlow WE, White E, Ballard-Barbash R, Vacek PM, Titus-Ernstoff L, Carney PA, Tice JA, Buist DS, Geller BM, Rosenberg R, Yankaskas BC, Kerlikowske
K .Prospective breast cancer risk prediction model for women undergoing screening mammography. J Natl Cancer Inst. 2006 Sep 6;98(17):1204-14.
- Tice JA, Cummings SR, Smith-Bindman R, Ichikawa L, Barlow WE, Kerlikowske K.Using clinical factors and mammographic breast density to estimate breast cancer risk: development and validation of a new predictive model.Ann Intern Med. 2008 Mar 4;148(5):337-47.
- Freedman AN, Seminara D, Gail MH, Hartge P, Colditz GA, Ballard-Barbash R, Pfeiffer RM. Cancer risk prediction models: a workshop on development, evaluation, and application. Natl Cancer Inst. 2005 May 18;97(10):715-23.
- Pilato B, Martinucci M, Danza K, Pinto R, Petriella D, Lacalamita R, Bruno M, Lambo R, D’Amico C, Paradiso A, Tommasi S. Mutations and polymorphic BRCA variants transmission in breast cancer familial members.Breast Cancer Res Treat. 2010 Mar 30.
- Rennert, Gad, Bisland-Naggan, Shantih, Barnett-Griness, Ofra, Bar-Joseph, Naomi, Zhang, Shiyu, Rennert, Hedy S., Narod, Steven A. Clinical Outcomes of Breast Cancer in Carriers of BRCA1 and BRCA2 Mutations.N Engl J Med 2007 357: 115-123
- Hines, L. M., Risendal, B., Slattery, M. L., Baumgartner, K. B., Giuliano, A. R., Sweeney, C., Rollison, D. E. and Byers, T. Comparative analysis of breast cancer risk factors among hispanic and non-hispanic white women. Cancer, 116: 32153223.
- Tam CY, Martin LJ, Hislop G, Hanley AJ, Minkin S, Boyd NF.Risk factors for breast cancer in postmenopausal Caucasian and Chinese-Canadian women.Breast Cancer Res. 2010;12(1):R2.
- Barnett GC, Shah M, Redman K, Easton DF, Ponder BA, Pharoah PD. Risk factors for the incidence of breast cancer: do they affect survival from the disease? J Clin Oncol. 2008 Jul 10;26(20):3310-6.