A pair of editorials in the July issue of Radiology promises to revive the screening mammography controversy that followed U.S. Preventive Services Task Force (USPSTF) recommendations for breast cancer screening revised in November 2009. “The USPSTF guidelines are not based on scientific evidence. Women should be urged to begin annual breast cancer screening at the age of 40,” stated Daniel B. Kopans, MD.
“Therapy only saves lives if cancers are found early. The death rate will almost certainly increase based on the USPSTF guidelines,” predicted Kopans, a professor of radiology at Harvard Medical School and senior radiologist in the breast imaging division at Massachusetts General Hospital in Boston.
USPSTF members disagree. “Medical evidence indicates that many women in their 40s who get routine screening mammograms will undergo unnecessary tests, procedures and, very rarely, treatment without any health benefit, while other women—about one per 1,000--will have their lives extended by mammography,” countered Ned Calonge, MD, USPSTF chair and chief medical officer of the Colorado Department of Public Health and Environment in Denver.
USPSTF revised the breast cancer screening guidelines in November 2009 to recommend against routine annual mammography screening for women in their 40s inciting a controversy among physicians and patient advocacy groups. Mammography screening supporters also questioned the recommendation to screen women between the ages of 50 and 74 every two years instead of annually.
Copious evidence supports mammography screening beginning at age 40, said Kopans, who provided examples:
- There are 15,000 to 20,000 fewer breast cancer deaths in the U.S. each year than in the pre-screening era;
- Forty percent of the years of life lost to breast cancer are among women diagnosed in their 40s;
- Randomized control trials show decreases of up to 44 percent in breast cancer deaths among women aged 40-49 years undergoing regular screening; and
- Seventy-five to 90 percent of women diagnosed with breast cancer each year are not high risk.
In addition, Kopans argued that USPSTF--a group that did not include a radiologist or medical oncologist--based its recommendations on flawed data. The task force relied on computer data rather than population studies to determine that improved therapies rather than screening account for most of the decrease in breast cancer deaths. Population studies demonstrate that the introduction of screening mammography rather than new therapies triggered declines in breast cancer death rates in Sweden.
On the other side of the debate, Calonge and the USPSTF pointed to "rigorous, impartial analysis of the best scientific evidence," including:
- Analysis of data from the Breast Cancer Surveillance Consortium shows that rates of false-positive findings and recall rates in the U.S. are at least twice those in Canada and Europe while detection rates are similar and cancer rates increase and false positive mammograms decrease with age;
- Meta-analysis of nearly 350,000 women indicate an absolute risk reduction in mortality of 0.025 percent in the women aged 40 to 49 years participating in routine mammography screening;
- The National Cancer Institute-sponsored Cancer Intervention and Surveillance Monitoring Network calculated an additional three percent mortality reduction and an additional 2,250 false positives for every 1,000 women aged 40 to 49 screened.
Calonge also contended that computer modeling overcomes shortcomings of randomized clinical trials.
Kopans, meanwhile, also questioned the evolving semantics and practical clinical applications of the recommendations. The initial guideline stated, “The USPSTF recommends against routine provision” of screening mammography for women aged 40 to 49.
Now, the USPSTF suggests it meant women should consult their physicians about the benefits of screening mammography; however, most physicians rely on the task force’s recommendations without considering implied nuances. In fact, a recent Annals of Internal Medicine poll reports that 67 percent of its readers plan to follow USPSTF guidelines.
In addition, payors base coverage decisions on USPSTF guidelines, so whether or not women can have a discussion with their primary care physician about the benefits of screening mammography may be a moot point for those women without coverage for screening mammography.
Finally, state governments are responding to the guidelines.