Physicians on both sides of yesterday’s debate about the US Preventive Services Task Force (USPSTF) Guidelines for Breast Cancer Screening used the same data to make their points, but essentially disagreed on when screening should begin and how often screening should take place.
At issue during the John and Marney Mathers Lecture was the USPSTF guideline that assigns a C grade to the practice of screening for women 40 to 49 and the recommendation for biannual screening for women ages 50 to 74.
George Sawaya, MD, professor in obstetrics, gynecology and reproductive sciences and epidemiology & biostatistics at the University of California, San Francisco, argued for following the USPSTF guidelines. He outlined the process by which the task force assigns grades, including using evidence review in an analytical framework that judges the certainty and magnitude of potential harms and benefits of screening.
Looking at striking a balance between the benefits such as fewer deaths from breast cancer to fewer occurrences of advanced breast cancers and the harms such as false positives, benign biopsies, and overtreatment of ductal carcinoma in situ, the task force looked at randomized controlled trials, observational studies and summaries of both experimental and observational evidence.
“This is more of a mystery than a puzzle. Should we even draw a line or should we just simply put this in front of all the patients and let them make a choice? Or should we take our best judgment about where the right balance of benefits and harms might be?” said Dr. Sawaya.
The task force gave a B recommendation to a biannual screening mammography for women 50 to 74, meaning they thought the net benefit, or the benefit minus the harms, was of a moderate magnitude. For women 40 to 49, the task force thought the net benefit was still positive, or there’s more benefit than harm, but the magnitude of that was small because of data on false positives, benign biopsies, and overtreatment.
“Both of these are positive recommendations,” Dr. Sawaya said. “But for the C recommendation, they recommended strongly that women who place a higher value on their potential benefits than the potential harms may choose to begin biannual screening between the age of 40 to 49. Sometimes, you have to step up to the plate and make your best judgment.”
Mark Pearlman, MD, S. Jan Behrman professor in reproductive medicine in the department of obstetrics/gynecology and professor of surgery with the University of Michigan Hospital and Health Systems in Ann Arbor, argued that the limited harms of potentially needing an additional screening due to a false positive or the stress of a needle biopsy are not equivalent to the benefit of preventing a death from breast cancer or an advanced case, especially when considering that breast cancers in younger women tend to be more aggressive.
He offered a rationale for annual testing of women in their 40s based on the sojourn time, or the time interval when cancer may be detected by screening before it becomes symptomatic.
“Women who have breast cancers that are detected at younger ages tend to have biologically more aggressive tumors, and sojourn time doubles in women in their 40s compared to women in their 70s,” said Dr. Pearlman.
He suggested that physicians might want to encourage younger women, especially, to have annual screenings and potentially move to biannual screening as they get older.
“The American Cancer Society in 2015 actually picked up on this and said for earlier detection younger women may benefit from more frequent testing, and their recommendation was that starting at age 55 and older, women may transition to biannual screening or have the opportunity to continue screening annually,” he said.
Dr. Pearlman also noted that a C grade on biannual screening in younger women is considered failing in terms of insurance payment, which may serve as a deterrent to screening if the current protections in the Affordable Care Act are overturned.
Mathers Lecture Streaming Colloquia Video