NEW YORK (Reuters Health) – In an update to its 2002 guidelines, the US Preventive Services Task Force (USPSTF) is now recommending that mammographic screening for breast cancer not begin until age 50.

For women in their 40s who are at high risk for breast cancer, however, regular mammographic screening starting before age 50 may be appropriate depending on the circumstances, according to the guidelines, which appear in the November 17th issue of the Annals of Internal Medicine.

In another change, the USPSTF now advocates biennial rather than annual mammographic screening. The benefits of biennial and annual screening are similar, but the potential harms, such as anxiety and the impact of false-positive results, are less with biennial screening, according to the report.

Both of the changes are likely to stir up strong debate in the medical community and not everyone is accepting them with open arms.

Dr. Daniel B. Kopans, a professor of radiology at Harvard Medical School and senior radiologist of the Breast Imaging Division at Massachusetts General Hospital, Boston, believes that implementation of the new guidelines will cost many women their lives.

“Mammography screening has been shown in the most rigorous scientific studies to significantly decrease breast cancer deaths for women ages 40-74,” Dr. Kopans told Reuters Health. “The USPSTF guidelines ignore the facts, and their implementation will severely reduce the benefit that has been achieved and will increase the death rate in the US and set back women’s health 20 years.”

The new guidelines are based in part on research headed by Dr. Jeanne S. Mandelblatt, from Lombardi Comprehensive Cancer Center, Washington, DC. Dr. Mandelblatt led a team that developed 6 models of breast cancer incidence and mortality in the U.S. to evaluate 20 screening strategies. The 6 independent modeling teams included researchers from the some of the nation’s leading cancer centers.

In addition, Dr. Heidi D. Nelson, from the Oregon Health and Science University, Portland, and colleagues conducted a systematic review and meta-analysis of evidence published through 2008.

The updated guidelines and the supporting studies appear in the November 17 issue of Annals of Internal Medicine.

The USPSTF found “fair evidence that women who have screening mammography die of breast cancer less frequently than women who do not have it, but the benefits minus harms are small for women aged 40 to 49 years.”

Due to insufficient data, the USPSTF was unable to recommend for or against mammographic screening for women 75 and older.

In the meta-analysis: –For women aged 39 to 49 years, the pooled relative risk for breast cancer mortality in those randomized to screening was 0.85, with a number needed to invite for screening of 1904. –Between ages 50 and 59 years, the RR with screening was 0.86, with a number needed to invite of 1339. –Between 60 and 69 years, the RR with screening was 0.68 and the number needed to invite was 377.

Although breast self-examination has been taught to many women, the USPSTF no longer endorses this practice because “no benefit has been shown” for it. In fact, even when breast examination is performed by a clinician, it is unclear whether the information gleaned adds anything beyond that obtained with mammography, the group found.

As to the type of mammography that should be performed, the USPSTF found insufficient data to definitively compare digital mammography or MRI with regular film mammography.

In an editorial, Dr. Karla Kerlikowske of the San Francisco Veterans Affairs Medical center summarizes:

–The move “to recommend against universal screening mammography for women aged 40 to 49 years and instead advocate for individualized informed decision making….is based, in part, on…randomized, controlled trials with 10 or more years of follow-up” and also on statistical modeling results.

–The change to biennial screening mammography for women ages 50 to 69 years is based on “consistent” evidence from statistical models and clinical trials “that biennial screening for (this group) maximizes the potential benefits…while minimizing harms.

–As for extending screening mammography to women aged 70 to 74 years, “Data from randomized controlled trials are inadequate to draw conclusions about the benefits of screening in this age group; therefore the primary evidence about whether to extend screening mammography comes from models.”

It is how these models were used that is particularly troubling to Dr. Kopans.

“Instead of using direct data,” he explained, “the USPSTF used their chosen computer models to extrapolate benefit ignoring models that contradict their conclusions. Despite the fact that their models show that the most lives are saved by screening beginning at the age of 40, they decided to ignore their own results and change their guidelines.”

“Given the irrefutable evidence that mammography screening saves lives, the USPSTF should be held accountable for the unnecessary breast cancer deaths that will result if their irresponsible recommendations are adopted.”

Reference:
Ann Intern Med 2009;151:I-44,727-737,738-747,750-752.