Prevalence of breast cancer overdiagnosis rises with age
Click Here to Manage Email Alerts
Key takeaways:
- About 31% of breast cancers in women aged 70 to 74 years were potentially overdiagnosed.
- For women aged at least 85 years, the overdiagnosis rate was up to 54%.
Breast cancer screening after age 70 years was linked to a higher incidence of cancer that would probably not have caused symptoms in the patient’s lifetime, indicating that overdiagnosis may be common in this population, researchers said.
Breast cancer overdiagnosis — “defined as detecting a cancer, often through screening, that would not have caused symptoms in a person’s lifetime” — has become an increasingly recognized harm of screening in older women, Ilana B. Richman, MD, MHS, an assistant professor at Yale School of Medicine, and colleagues wrote in Annals of Internal Medicine.
Previous modeling studies have indicated that overdiagnosis may occur in an estimated 0.2 to 7.5 older women per 1,000 screened for breast cancer, depending on factors like comorbidity and age. So, Richman and colleagues conducted a retrospective cohort study to approximate the risk for overdiagnosis linked to breast cancer screening among older women.
The researchers compared the cumulative incidence of breast cancer in older women who continued screening in the next interval with those who did not. They included 54,635 women aged 70 years or older who had recently been screened.
Richman and colleagues found that the adjusted cumulative incidence of breast cancer among women aged 70 to 74 years was 4.2 cases per 100 unscreened women (95% CI, 3.5-5) and 6.1 cases per 100 screened women (95% CI, 5.7-6.4). This means approximately 31% of breast cancer in screened women were potentially overdiagnosed, they wrote.
The researchers found that possible overdiagnoses increased with the age of women screened. For those aged 75 to 84 years, the cumulative incidence was 2.6 per 100 unscreened women (95% CI, 2.2-3) compared with 4.9 per 100 screened women (95% CI, 4.6-5.2). Richman and colleagues estimated that 47% of cases in this age group were potentially overdiagnosed.
Finally, for those aged 85 years and older, the cumulative incidence was 1.3 (95% CI, 0.9-1.9) among those not screened and 2.8 (95% CI, 2.3-3.4) among those screened. That translates to an overdiagnosis rate of up to 54%, according to the researchers.
They also noted that they did not observe statistically significant drops in breast cancer–specific mortality connected with screening.
Because continued screening was linked to greater breast cancer incidence, Richman and colleagues concluded that overdiagnosis might be common among older women diagnosed with breast cancer after being screened. The findings raise important questions, they wrote: Are the harms of overdiagnosis balanced by benefits? If so, for whom?
“The relative risk for overdiagnosis increases with age and is highest for the oldest women or those with lowest life expectancy,” they wrote. “Overdiagnosis should be explicitly considered when making screening decisions, along with considering possible benefits of screening.”
Otis W. Brawley, MD, a professor of oncology at Johns Hopkins School of Medicine, and Rohan Ramalingam, also of the department of oncology at Johns Hopkins School of Medicine, wrote that “many find ‘overdiagnosis’ a confusing term and an even more difficult concept to accept” because the concept “challenges the widely accepted dogma that the natural history of cancer is that it always grows, spreads, and eventually kills.”
“Estimating the effect of overdiagnosis is difficult. Richman and colleagues acknowledge this and do a wonderful job explaining the limitations of overdiagnosis studies,” they wrote. “The important point of their study is that it provides credible evidence that overdiagnosis exists among older women, and it is not a trivial proportion who experience overdiagnosis.”
References:
- Brawley OW, et al. Ann Intern Med. 2023;doi:10.7326/M23-1895.
- Richman IB, et al. Ann Intern Med. 2023;doi:10.7326/M23-0133.
Perspective
Back to Top
As this data implies, there are some patients for whom screening does not make sense. Patients who have significant other medical problems in whom breast cancer would not be treated certainly should not be screened. If a patient had a very advanced form of another type of cancer or otherlife-threateningmedical problem, that’s where your focus should be. And then if there’s a patient who has decided that she would not undergo treatment regardless of what was found based on age, medical issues, religious or other philosophical decisions, then, of course, that person should not be screened.
Beyond that, from the American Cancer Society, we do believe, in general, early detection, when thoughtfully done, can improve cancer-specific outcomes. So we want to always be cautious about the word “overdiagnosis.” Overdiagnosis can really be determined only retrospectively. A cancer diagnosis that seems indolent may evolve into a tumor that is potentially lethal. Thus, a screening discussion needs to be nuanced and thoughtful and take into account the health of the patient and the potential toxicities of therapy.
I personally favor gathering as much information as possible before you make any definitive cancer therapy decisions. Having screening information about a cancer does not necessarily mean that cancer needs to be treated urgently, but not screening at all could miss a potentially lethal cancer. Hopefully, as scientific discoveries accelerate, we will develop precision based well-tolerated therapies that change the focus from potential “overdiagnosis” to the prevention of clinically advanced cancers.
Collapse
Read more about
Click Here to Manage Email Alerts