Dr. Jeff Hersh: Update on breast cancer screening
Q: I saw that they are now not recommending mammograms for women under 50. Doesn't this put some women at greater risk?
A: There was an increase in breast cancer diagnoses in the 1990s due to improved screening; in fact, most of this increase was for early stage disease.
A decline in breast cancer cases after 2003 was due to the decline in hormone usage for post-menopausal women because of the Women's Health Initiative results reported in 2002.
However, breast cancer remains a major health issue, with over 200,000 American women diagnosed and 40,000 dying from this disease each year.
Risk factors for developing breast cancer include advanced age, genetic factors and estrogen exposure. Overall, mammography is still the most useful tool to screen for this disease.
I believe the "some women" you refer to is the U.S. Preventive Services Task Force, which no longer recommends routine screening mammography for non-high risk women in their 40s (the American Academy of Family Physicians still recommends mammography starting at age 40).
Since the risk of developing breast cancer increases with age, more women between ages 40 and 50 would need mammograms to detect a case of breast cancer than women above age 50; the revised recommendation is based on this concept. Note that screening with a Clinical Breast Exam (CBE, a thorough breast exam performed by a health care provider) is still recommended.
Although the total number of women saved by screening mammography of all women age 40 to 50 is less than screening the same number of women over age 50, this does not mean that earlier mammography does not save lives. In fact, a meta-analysis (a review of many studies combined together) found that screening women age 39 to 48 decreases the risk of death from breast cancer by 15 percent.
Other studies have shown that mammograms for women in their 40s detect tumors at an earlier stage than if only CBE is done. There is a downside to screening mammography; the number of unnecessary biopsies is higher because of occasional false-positive mammograms (suspicious test result although there is no cancer).
Women of Hispanic, Asian and Pacific Island ancestry are more likely to be diagnosed with breast cancer in their 40s than Caucasians. Therefore, delay of mammographic screening for all women until age 50 would be more detrimental to these minorities.
There are other screening tests that may be considered for breast cancer:
-- Digital mammography offers a screening advantage for women under age 50 and for those with dense breasts.
-- Women at very high risk of breast cancer benefit from screening with MRI in tandem with mammography. This is not true for all women; the American Cancer Society specifically recommends against MRI screening for women with a lifetime risk of breast cancer estimated to be less than 15 percent because MRI has a higher false positive rate.
-- CBE is beneficial, even though some studies have noted that mammography detects 90 percent of screening-detected breast cancer whereas CBE only 50 percent; so overall it is not as good as mammography, although for some patients it may be the preferred screening method.
-- Although breast self-examination is often recommended, few randomized trials have shown benefit, and one very large study in China showed that women instructed in breast self-examination did not have any reduction in mortality.
-- Ultrasound has been shown to be useful to further evaluate suspected breast cancer noted from CBE or mammograms, and is also useful to help guide biopsies.
-- There is no data showing survival benefit from thermography.
There are other open questions about breast cancer screening; specifically how frequent screening should be done (although CBE is recommended with annual physicals, the best frequency to do screening mammography is not known -- every two years is the common guideline).
Finally, the age to stop screening mammography is not known, and likely depends on other factors such as the patient's overall life expectancy due to other medical conditions.
Breast cancer screening saves lives, and the best screening option for you should be discussed with your health care provider.
Jeff Hersh, Ph.D., M.D., F.A.A.P., F.A.C.P., F.A.A.E.P., can be reached at DrHersh@juno.com.