Discussion and recommendations for breast cancer screening
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Recommended Mammography screening rates
There are a variety of opinions regarding the frequency and at what age mammogram is recommended for breast cancer screening. Women aged 50-69 should be screened for breast cancer approximately every 18 months regardless of risk factors.
The American Cancer Society and the National Cancer Institute both recommend annual or biennial screening for women between 40 to 49, if at average risk . However, recent evidence suggests that tumors may grow more rapidly in younger women, so the trend is to recommend annual screening for all women between 40 and 49.
For women between 40 and 49, and for women over age 70, screening should be annual if there are risk factors present. These include:
- Family history of breast cancer ( sister, mother, daughter)
- Previous radiation therapy for hodgkins disease before age 30
- Family history of BRCA1 and BRCA2 gene variants
- First pregnancy at 30 years of age or older
- Late menopause
- More than four years of hormone replacement therapy
Recommended Age-Group and Mammography Screening Intervals
The following table gives the recommended screening interval guidelines for normal and high risk women, as suggested by various cancer societies around the world.
There are many ‘high-risk’ factors, but the main ones are first degree female relative (mother, sister, daughter), and familial genetic predisposition (family history). ‘Interval’ is given in years unless otherwise stated.
| Institution | Screening Interval | high-risk | Examinations | ||||||||
| society | country | 40-49 | interval | 50-59 | interval | >70 | interval | = or > 40 | interval | annual phsyician breast exam | monthly breast self exam |
| American Cancer Society | USA | y | 1 | y | 1 | y | 1 | y | 1 | y | y |
| American College of Radiology | USA | y | 1 | y | 1 | y | 1 | y | 1 | y | y |
| National Cancer Institute | USA | y | 1-2 | y | 1-2 | y | 1-2 | y | 1 | y | y |
| National Institute of Health | USA | y | 1-2 | y | 1-2 | y | 1-2 | y | 1 | y | y |
| United States Preventive Task Force | USA | grade B. ( fair evidence that benefits outweight harms) | 1-2 | y | 1-2 | Grade B | 1-2 | Y | 1 | Y | unclear |
| Canadian Task Force on Preventive health care | Canada | Grade C (no recommendation either way) | – | Y | 2 | Grade C | – | Y | 1 | Y | N |
| Agence Nationale d’accreditation et d’Evaluation en Sante | France | N | – | Y | 2 | 74 | 2 | Y | 1 | Y | Y |
| National Health Service Breast Screening Programme | United Kingdom | N | – | y (50-64) | 3 | 70 | 3 | y | 1 | y | – |
| Swedish National Board of Health and Welfare | Sweden | 40-54 | 12-18 months | 55-74 | 18-24 months | 74 | 18-24 months | y | 1 | y | y |
Anticipated breast cancer mortality reduction due to proper mammography screening
For women aged 40-49 the mortality rate is improved for screening at intervals less than two years. This is because the growth rate for cancer is typically faster for women in this age group.
Mammography screening should occur every 12 to 18 months, ideally. It is anticipated that mortality rates may be reduced by almost 30% by screening at this interval. Mortality rates for women aged 50 to 69 may by improved by almost 40% by regular mammography screening.
According to a recent health insurance plan study, screening mammography starting at age 40 to 49 resulted in a 5% decrease in the mortality rate over 5 years, and a 25% decrease in morality rates over 18 years.
If mammography screening starts in the 50 to 64 age group, there is a 40% decrease in mortality at 9 years, a 30% decrease in mortality at 10 to 14 years, and a 21% decreased mortality rate at 18 years. Of course, one of the major issues with breast cancer screening is compliance, and women getting mammogram after age 50 seem to be far more inclined to attend annual screening checkups when compared to women getting mammogram before age 50.
References
- National Guidelines Clearinghouse, Guideline Synthesis, Screening for Breast Cancer.
- National Cancer Advisory Board
- LE COLLEGE, Vol. XL, no 1 – Mai/Juin 2000
- Feigs SA, Estimation of currently attainable benefit from mammographic screening of women aged 40-49 years. Cancer;75(10):2412-9.
- Smart CR, Hendrick RE, Rutledge JH. Et al. Benefit of mammography screening in women ages 40-49 years:
current evidence from randomized controlled trials. Cancer 1995;75(7):1619-26. - Tabar L, Vitak B, Chen HH, et al. The Swedish Two-County Trial Twenty Years Later. Radiologic Clinics of North America Vol. 38, No 4, July 2000.
- Jackson V. Breast imaging Update 2003. Montreal, Canada, August 8-10, 2003
- Strumpf EC, Chai Z, Kadiyala S. Adherence to cancer screening guidelines across Canadian provinces: an observational study. BMC Cancer. 2010 Jun 18;10:304.
- Richardson, LC., Rim, SH., Plescia, M. Vital Signs: Breast Cancer Screening among Women Aged 50–74 Years — United States, 2008. orbidity & Mortality Weekly Report. 2010;59(26):813-816.
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