Probability of Breast Cancer in American Women

Key Points

• The National Cancer Institute, a component of the National Institutes of 

Health, estimates that, based on current rates, 12.7 percent of women 

born today will be diagnosed with breast cancer at some time in their 

lives. 

• Because rates of breast cancer increase with age, estimates of risk at 

specific ages are more meaningful than estimates of lifetime risk. 

• An estimated risk represents the average risk for all women in the United

States as a group. This estimate does not indicate the risk for an 

individual woman because of individual differences in age, family 

history, reproductive history, race/ethnicity, and other factors. 

• Estimated lifetime risk of breast cancer has gone up gradually over the 

past several decades. This year it declined slightly. 

The National Cancer Institute’s (NCI) Surveillance, Epidemiology, and End Results 

(SEER) Program has published its SEER Cancer Statistics Review 1975–2003 (1). This report 

estimates that, based on current rates, 12.7 percent of women born in the United States today will 

develop breast cancer at some time in their lives. This estimate is based on breast cancer 

statistics for the years 2001 through 2003. 

This estimate means that, if the current rate stays the same, women born now have an 

average risk of 12.7 percent (often expressed as “1 in 8”) of being diagnosed with breast cancer 

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at some time in their lives. On the other hand, the chance that they will never have breast cancer 

is 87.3 percent (expressed as “7 in 8”). 

 In the 1970s, the lifetime risk of being diagnosed with breast cancer in the United States 

was just under 10 percent (often expressed as “1 in 10”). The estimated lifetime risk has 

generally been rising gradually since then; this year, the estimated risk decreased slightly. 

 The last five annual SEER reports show these estimates of lifetime risk: 

• 13.4 percent for 1997 through 1999 (“1 in 7.45,” often expressed as “1 in 7”) 

• 13.5 percent for 1998 through 2000 (“1 in 7.40,” often expressed as “1 in 7”) 

• 13.4 percent for 1999 through 2001 (“1 in 7.47,” often expressed as “1 in 7”) 

• 13.2 percent for 2000 through 2002 (“1 in 7.56,” often expressed as “1 in 8”) 

• 12.7 percent for 2001 through 2003 (“1 in 7.87,” often expressed as “1 in 8”) 

SEER statisticians expect some variability from year to year. Slight changes, such as the 

one reported this year, may be explained by a variety of factors, including minor changes in risk 

factor levels in the population, slight changes in screening rates, or just random variability 

inherent in the data. 

The estimated probability of being diagnosed with breast cancer for specific age groups 

and for specific time periods is generally more informative than lifetime probabilities. Estimates 

by decade of life are less influenced by changes in life expectancy and incidence rates. The 

SEER report estimates the risk of developing breast cancer in 10-year age intervals (1). These 

calculations factor in the proportion of women who live to each age. In other words, they take 

into account that not all women live to older ages, when breast cancer risk becomes the greatest. 
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A woman’s chance of being diagnosed with breast cancer is: 

• from age 30 through age 39 . . . . . . 0.43 percent (often expressed as “1 in 233”) 

• from age 40 through age 49 . . . . . . 1.44 percent (often expressed as “1 in 69”) 

• from age 50 through age 59 . . . . . . 2.63 percent (often expressed as “1 in 38”) 

• from age 60 through age 69 . . . . . . 3.65 percent (often expressed as “1 in 27”) 

These probabilities are averages for the whole population. An individual woman’s breast 

cancer risk may be higher or lower, depending on a number of factors, including her family 

history, reproductive history, race/ethnicity, and other factors that are not yet fully understood. 

To calculate an individual’s estimated risk, see the Breast Cancer Risk Assessment Tool at 

http://www.cancer.gov/bcrisktool/ on the Internet. 

For more information on the subject of lifetime risk of breast cancer, see 

http://surveillance.cancer.gov/statistics/types/lifetime_risk.html on the Internet. 

Selected Reference 

1. Ries LAG, Harkins D, Krapcho M, et al. SEER Cancer Statistics Review, 1975–2003. 

Bethesda, MD: National Cancer Institute, 2006. 

# # # 

Related Resources

Publications (available at http://www.cancer.gov/publications) 

• National Cancer Institute Fact Sheet 3.62, Genetic Testing for BRCA1 and BRCA2: 

It’s Your Choice

• National Cancer Institute Fact Sheet 4.18, Breast Cancer Prevention Studies

• National Cancer Institute Fact Sheet 5.14, Improving Methods for Breast Cancer 

Detection and Diagnosis

• National Cancer Institute Fact Sheet 5.28, Screening Mammograms: Questions and 

Answers
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National Cancer Institute (NCI) Resources

Cancer Information Service (toll-free)

Telephone: 1–800–4–CANCER (1–800–422–6237) 

TTY: 1–800–332–8615 

Online 

NCI’s Web site: http://www.cancer.gov 

LiveHelp, NCI’s live online assistance: 

https://cissecure.nci.nih.gov/livehelp/welcome.asp

This fact sheet was reviewed on 10/5/06