The risk of breast cancer overdiagnosis was higher for women older than 70, meaning more women were diagnosed with asymptomatic cancer that would not be fatal. Among women over 85, the likelihood of overdiagnosis exceeded 50%, according to study findings published in the Annals of Internal Medicine.

“Overdiagnosis refers to a phenomenon where we find breast cancers through screening that never would have caused symptoms,” Ilana Richman, MD, of Yale School of Medicine, said in a press release. “Overdiagnosis can occur when cancers grow very slowly or if a person’s life expectancy is short.”

Guidelines on breast cancer screening for older women are not well established since the risks and benefits can be uncertain.

Richman and colleagues assessed the likelihood of overdiagnosis linked to breast cancer screening among older women. For their analyses, they used data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results Medicare Registry. This retrospective analysis included 54,635 women ages 70 and older without a prior history of breast cancer who were recently screened.

The researchers found that the risk of overdiagnosis increased greatly as women aged. For women between the ages of 70 and 74, six women out of every 100 screened were diagnosed with breast cancer, compared with four out of 100 unscreened women. This means that 31% of women who were screened were potentially overdiagnosed.

Among women between the ages of 75 and 84, the researchers reported that five out of every 100 screened were diagnosed with breast cancer, compared with three out of 100 unscreened women, meaning 47% of women screened were potentially overdiagnosed. And among women 85 and older, three out of every 100 screened were diagnosed, compared with just one out of 100 unscreened women, meaning 54% were potentially overdiagnosed.

When the researchers took life expectancy into account, overdiagnosis rates for screened women rose even more. For women with a life expectancy of more than 10 additional years, 32% were overdiagnosed. This rose to 53% for those with a life expectancy between six and 10 years and to 63% for those with a life expectancy of at most five years.

Ultimately, the researchers did not find any statistically significant improvements in breast cancer-specific death rates linked to screening.

“Finding these breast cancers can lead to worry and can result in intensive treatments, without improving length or quality of life,” Richman said. “The findings from this study emphasize the need for a careful evaluation of the benefits and harms of screening older women.”

“While our study focused on overdiagnosis, it is important to acknowledge that overdiagnosis is just one of many considerations when deciding whether to continue screening,” she added. “A patient’s preferences and values, personal risk factors, and the overall balance of risks and benefits from screening are also important to take into account when making screening decisions.”

Click here to read the study abstract in the Annals of Internal Medicine.

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