Breast cancer overdiagnosis may be common among older women, researchers contend in a new analysis published Monday in the Annals of Internal Medicine [1].

The findings are derived from a retrospective study comparing the cumulative incidence of breast cancer among older women who continued screening past age 70 versus those who did not.

The final sample from the SEER-Medicare registry included 54,635 women, with the analysis tracking instances of breast cancer diagnoses and death spanning up to 15 years of follow-up. For women age 70 to 74, the authors estimated that 31% of screening-detected breast cancer cases were potentially overdiagnosed. The number leapt to 47% for women age 75 to 84 and 54% for those 85 and older.

“That finding points to a real need for better tools to identify which women may benefit from screening and which breast cancers are unlikely to be progressive, so that we can avoid overtreatment,” lead author Ilana B. Richman, MD, an internal medicine specialist with the Yale School of Medicine, said in a video accompanying the analysis.

Stratifying for life expectancy, the authors estimated that the proportion of breast cancer overdiagnosis was 32% for screened women with 10 or more years left to live. The number jumped to 53% for those with a life expectancy of six to 10 years and 65% at five years left to live or less. Richman et al. found no statistically significant reductions in breast cancer-related death tied to screening individuals after age 70.

The study estimated an absolute breast cancer overdiagnosis risk at about 2%. This number stayed fairly consistent across different age categories and life expectancies.

“Whether 2% seems high or low depends on how you perceive that risk, but it’s clearly not the most common outcome among women who are screened” Richman said. “At the same time, among women who are screened and diagnosed with breast cancer, a considerable portion of those breast cancers are potentially overdiagnosed,” she added.

Richman offered two key takeaways from the study.

“The risk of overdiagnosis has to be weighed against any potential benefits of screening, but making that calculus for an individual is difficult, given the uncertainties involved,” she said. “Second, talking about overdiagnosis is difficult. It’s an abstract concept. It’s unfamiliar to many people, and it’s not directly observable for any one individual. And so, working that conversation into the confines of a busy clinical encounter is not easy, and I think it speaks to the need for tools that can support these conversations, can provide information to women and can help ensure that decisions about screening are concordant with our patients’ values.”

The analysis comes after the U.S. Preventive Services Task Force recently released updated screening guidelines, urging for further research on the benefits and harms of imaging women older than 75, believing current evidence is insufficient.