This recommendation was made in 2009. The published article giving the data for many alternative screening strategies is available at
http://www.uspreventiveservicestaskf...r/brcanart.pdf
It is a data intense read but is very clear on the relative benefits and risks of each strategy. Their recommendations only apply to patients with no symptoms, no increased genetic risk, and they concede that there are insufficient data on whether extending the screening age down to 40 should be considered for African-American women due to earlier risk. The data shows that by extending the screening recommendation down to age 40-69 rather than 50-69 you add about 10 days of life span for the average woman. It is important when reading the report that there were
no considerations of dollars. The recommendation was made entirely based on models of benefit and risk to the patient and extension of life. Also keep in mind the baseline. After age 40 without ever getting screening a woman has a 3% risk of dying from breast cancer, or the other way, a 97% chance of dying from something other than breast cancer. The younger you initiate screening the more false positive results, the greater number of misreadings, extra biopsies, radiation exposure which in itself can cause cancer, but also the greater benefit in lives saved from breast cancer. There is no scenario for routine screening that would have recommended screening for a 38 yr old. As always, each person in discussion with their own doctor can make the decision to screen or not at any age.