New Evidence Fuels Debate Over
Mammography Screening Frequency
A new study published in the Annals of Internal Medicine says that for women aged 40 to 49 with an increased risk of developing breast cancer, the benefits of mammography screening every other year outweigh the potential harms, according to Jeanne Mandelblatt, MD, MPH, the article’s senior author.
Mandelblatt is associate director for population sciences at Georgetown Lombardi Comprehensive Cancer Center.
The risk factors that increase risk to twice the average include family history and having extremely dense breasts. These conditions affect one out of every five American women aged 40 to 49, she says in the article.
“Our research suggests the benefit-harm balance is tipped in favor of every-other-year screening for women in their 40s who are at about twice the average risk of developing breast cancer,” says Mandelblatt, who worked with an international team of researchers. “The study also determined that the balance of benefits and potential harms in this same group is not favorable when increasing the frequency of mammography screening to once a year unless a woman has at least a four-fold increase in risk.”
Not Intended to Guide Clinical Care
The researchers characterized benefits of screening as life years gained and breast cancer deaths averted. Harms are defined as false-positive mammography examinations that sometimes lead to additional procedures, pain and anxiety.
“Reducing the false-positive rate is crucial to improving the balance of benefits and harms for screening regimens for women of all ages,” she says. “We will continue to debate what is right for women ages 40-49 until we have better screening tests. Mammography is the best tool we have, but, like other medical tests, it is not perfect.”
Mandelblatt emphasizes that the findings are based on models of the U.S. population and don’t constitute a recommendation or advice for individual women. The findings provide new evidence supporting the use of risk-based screening.
“These results are not intended to guide clinical care, but to provide evidence to groups striving to individualize screening guidelines based on risk factors,” she explains.
Digital vs. Film
The new study also finds small differences in benefits between film and digital mammography screening. But digital mammography screening did result in substantially more false-positive results than film, and thus represents greater harm.
Mandelblatt says putting these results into practice will not be straightforward.
“For example, the need to have a mammogram to determine breast density is an important point to consider in regard to implementing risk-based guidelines based on breast density,” she says.
She says some groups might see this as a reason to recommend a baseline mammography.
“Ultimately, though, the decision of when to start screening and how often, and whether to have digital or film mammography should be left to women and their health care providers,” Mandelblatt says.
In 2009, the U.S. Preventive Services Task Force recommended mammography screening every other year for women aged 50 to 74 who have an average risk of developing the disease but concluded that for average risk women aged 40 to 49 years, biennial screening mammography offered a small benefit but considerable harms.
Those findings were based in part on earlier research conducted by Mandelblatt and her colleagues.
“I know that women want to know what they should do and the message remains unchanged,” Mandelblatt concludes. “They should talk about their risk factors and preferences for the harms of screening with their health care providers to make the best decision for themselves.”
(May 2, 2012)