User:Hwebb2/Mammography

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For the average woman, the U.S. Preventive Services Task Force recommends (2016) mammography every two years between the ages of 50 and 74, concluding that "the benefit of screening mammography outweighs the harms by at least a moderate amount from age 50 to 74 years and is greatest for women in their 60s". The American College of Radiology and American Cancer Society recommend yearly screening mammography starting at age 40. The Canadian Task Force on Preventive Health Care (2012) and the European Cancer Observatory (2011) recommend mammography every 2 to 3 years between ages 50 and 69. These task force reports point out that in addition to unnecessary surgery and anxiety, the risks of more frequent mammograms include a small but significant increase in breast cancer induced by radiation. (=ADD OR EDIT=)

The radiation exposure associated with mammography is a potential risk of screening, which appears to be greater in younger women. In scans where women receive 0.25-20 Gray (Gy) of radiation, they have more of an elevated risk of developing breast cancer. A study of radiation risk from mammography concluded that for women 40 years of age and older, the risk of radiation-induced breast cancer was minuscule, particularly compared with the potential benefit of mammographic screening, with a benefit-to-risk ratio of 48.5 lives saved for each life lost due to radiation exposure. This also correlates to a decrease in breast cancer mortality rates by 24%. However, this estimate is based on modelling, not observations. In contrast epidemiologic studies show a high incidence of breast cancer following mammography screening. Organizations such as the National Cancer Institute and United States Preventive Task Force do not take such risks into account when formulating screening guidelines.

In 2014, the Surveillance, Epidemiology, and End Results Program of the National Institutes of Health reported the occurrence rates of breast cancer based on 1000 women in different age groups. In the 40-44 age group, the incidence was 1.5 and in the 45-49 age group, the incidence was 2.3. In the older age groups, the incidence was 2.7 in the 50-54 age group and 3.2 in the 55-59 age group. While screening between ages 40 and 50 is still controversial, the preponderance of the evidence indicates that there is some small benefit in terms of early detection. Currently, the American Cancer Society, the American College of Radiology, and the American Congress of Obstetricians and Gynecologists encourage annual mammograms beginning at age 40. The National Cancer Institute encourages mammograms one to two years for women ages 40 to 49. In contrast, the American College of Physicians, a large internal medicine group, has recently encouraged individualized screening plans as opposed to wholesale biannual screening of women aged 40 to 49. In 2009, the U.S. Preventive Services Task Force recommended that screening of women ages 40 to 49 be based on individual risk factors, and that screening should not be routine in this age group. Their report says that the benefits of screenings before the age of 50 do not outweigh the risks.

A 2016 review for the United States Preventive Services Task Force found that mammography was associated with an 8%-33% decrease in breast cancer mortality in different age groups, but that this decrease was not statistically significant at the age groups of 39–49 and 70–74. The same review found that mammography significantly decreased the risk of advanced cancer among women aged 50 and older by 38%, but among those aged 39 to 49 the risk reduction was a non significant 2%. The USPSTF made their review based on data from randomized controlled trials (RCT) studying breast cancer in women between the ages of 40-49.