Overdiagnosis of Cancer: Bringing an Important Problem into Focus
, by NCI Staff
For the third consecutive year, experts from around the world will convene to discuss the dilemma of overdiagnosis in many types of disease. Overdiagnosis is generally defined as the diagnosis of a disease or condition that is unlikely to ever cause harm.
The conference, Preventing Overdiagnosis, will take place September 1-3 in Bethesda, MD. Barry Kramer, M.D., director of NCI’s Division of Cancer Prevention, and a member of the conference steering committee, explained that this year’s conference has several areas of emphasis, including how best to communicate the concern about overdiagnosis to doctors and the public, identifying the root causes of overdiagnosis, and preventing or mitigating its harms.
Dr. Kramer has played a prominent role in research to identify and prevent cancer overdiagnosis, which studies have suggested may be triggered by widespread screening. Although some screening tests can detect cancer at its earliest stages, for example, Dr. Kramer has championed efforts to more closely scrutinize the risks of screening, including overdiagnosis and resulting overtreatment.
“One of the key issues today is that we can only detect overdiagnosis at the population level, as it is essentially an ‘invisible’ harm at the individual level to both health professionals and patients,” Dr. Kramer explained. “Our Holy Grail is to be able to detect it at the individual level and mitigate any possible harms before they can occur.”
To reach this point, he indicated, researchers would need to develop molecular fingerprints that would allow doctors to distinguish lesions that are most likely to progress to a potentially lethal cancer from those that are unlikely to progress or ever cause any harm.
Another key challenge is the language used to describe some very early stage lesions. Perhaps the best example is ductal carcinoma in situ (DCIS), the presence of cells in the breast duct that appear to be cancer but are not invasive. Some researchers have suggested that the presence of “carcinoma” in the condition’s name may trigger aggressive treatments because of the term’s alarming nature.
“One example of how we’ve been able to change the nomenclature is in cervical cancer, where we used to label pre-cancerous lesions as carcinoma in situ,” Dr. Kramer said. “But we’ve been able to effect a shift among doctors and how they communicate with their patients, and these lesions are no longer described as carcinomas, but are now typically referred to as cervical intraepithelial neoplasias, squamous intraepithelial lesions, or dysplasias.”
The result, he said, has been “a real decrease in alarm attached to the diagnosis.” This is a clear demonstration of how terminology can change perception, he continued, and how doctors or patients act on that perception.
Changing communications about overdiagnosis is a major focus of this year’s conference, Dr. Kramer said. But changing public perception will be a slow process, he believes. Whereas most media reports about clinical trial and treatment advances are accompanied by personal stories or anecdotes of patient success, that’s not as easy an objective to accomplish when there’s been overdiagnosis and a patient has been unnecessarily treated or harmed.
But Dr. Kramer points to some breast cancer advocates who have been outspoken about the potential harms of overdiagnosis. Such advocacy in this area, he said, is slowly making a difference.
Although there may be a perception that overdiagnosis is limited to some prevalent cancers like prostate and breast cancer, Dr. Kramer said that’s not the case.
He pointed to other examples, such as thyroid cancer and melanoma, as well as others, "where we’ve seen the incidence rates rise quickly without a concomitant decrease in mortality over a decade or more. Those are classic examples of overdiagnosis."