Increased rates of incidentalomas, and overdiagnosis, show that the medical field is still grappling with the benefits and consequences of ever-improving and possibly overused imaging, according to experts.
“As our imaging modalities have become more sensitive, the use of high-tech modalities like CT and MRI have led to more incidental findings,” said Vijay M. Rao, MD, chair of the department of radiology at Jefferson University Hospitals in Philadelphia.
However, whether the diagnosis of incidentalomas or overdiagnosis of cancer is due to improper or overuse of imaging is a difficult question, said Glenn D. Braunstein, MD, MACP, a professor of medicine at Cedars-Sinai Medical Center in Los Angeles and the former director of its thyroid cancer center.
“There are estimates made that about 30% of testing is unwarranted and that a lot of that testing turns out to be imaging,” he said.
Incidental findings, or incidentalomas, are findings detected during an imaging procedure that are unrelated to the primary objective of the examination. More sensitive imaging means that primary care physicians must have difficult conversations with patients about whether to address such findings or employ a “watch and wait” approach.
Although the exact frequency of discovery of incidentalomas is difficult to estimate, a retrospective study published in JAMA Internal Medicine in 2010 examined outcomes of participants who underwent imaging as part of a research project. Almost 40% had at least 1 incidental finding, most commonly aortoiliac calcifications, diverticulosis, and renal cysts. Of the participants with an incidental finding, 35 (6.2%) needed further clinical action, with a clear medical benefit resulting in only 6 (1.1%).
Incidentalomas can be discovered almost anywhere in the body.
“The most common places and types we see are thyroid nodules, liver cysts, and kidney cysts or lesions,” said Dr. Braunstein.
ACP Member Christine Berg, MD, a radiation oncologist with Johns Hopkins Medicine in Baltimore, Md., said that many imaging procedures of the lungs will turn up incidental findings since the top of the liver is often in the field.
Similarly, any chest CT might show a finding on the esophagus that looks suspicious for esophageal cancer or a finding on the heart or lungs, even if that was not the primary focus of the original imaging study.
“You may see incidentalomas when you image any organ,” Dr. Berg said. “The more you perform these very detailed, high-quality imaging procedures, the more things you are going to find.”
Several years ago, the ABIM Foundation launched its Choosing Wisely initiative in an attempt to eliminate unnecessary or inappropriate medical procedures. In an editorial published in Annals of Internal Medicine in 2012, Dr. Rao noted that 9 organizations published lists of 5 tests or treatments that they deemed overused, and that of those 45 tests, 24 were related to diagnostic imaging.
Otis W. Brawley Jr., MD, MACP, chief medical officer for the American Cancer Society, agreed, adding that physicians have become victims of their technologies, ordering imaging tests where 10 to 15 years ago they would have just performed a physical examination.
“Our overuse of technology, which is because of concerns about litigation, means that many of us have lost our diagnostic skills,” he said.
The issue of incidentalomas varies greatly from that of overdiagnosis. According to Dr. Berg, overdiagnosis of cancer occurs when a patient is found on a screening test to have cancer that is never going to become a clinical problem during the patient's lifetime. This could be because the cancer is very, very slowgrowing or the patient has a limited life expectancy due to other medical problems.
For example, a 2012 New England Journal of Medicine study estimated that about 1.3 million U.S. women were overdiagnosed with breast cancer in the last 30 years. The number of women diagnosed with early-stage disease had doubled with the introduction of screening mammography (an increase of 122 cases per 100,000 women), but only 8 per 100,000 would have progressed to advanced disease, the study found.
More recently, a perspective published in the New England Journal of Medicine discussed that thyroid cancer is now the most common cancer diagnosed in South Korea, diagnosed at a rate 15 times greater in 2011 than it was in 1993. This increase in diagnosis is mostly attributed to the fact that a thyroid ultrasound can be added to an exam for a nominal fee that patient can pay as an add-on to a free national screening program for common cancers. The increased incidence of thyroid cancer, though, has not forecast an increase in thyroid-cancer mortality, the perspective said.
Dr. Berg noted that there is evidence in the United States that thyroid cancer mortality has been increasing in men and women as far back as the late 1980s and that overdiagnosis cannot completely explain the increasing incidence.
“The problem is that we cannot tell beforehand whether a tumor is going to behave in an indolent fashion, and although there are attempts to try to discriminate that with molecular markers, we have not yet been able to tell which will behave aggressively and which will not,” Dr. Braunstein said. “By picking up some of these small growths, we are subjecting patients to more invasive procedures with their own risks and clinical harms.”
For example, Dr. Brawley said that the National Lung Screening Trial showed that CT screening in people at high risk for lung cancer will decrease the risk for death from the disease by 20%. However, of people with positive screening tests, about 97% had false positives and a small percentage of patients who underwent diagnostic evaluation were exposed to adverse events such as hospitalization or death.
Addressing incidentalomas with patients
Regardless of how or why they are discovered, Dr. Brawley acknowledged that discussing incidentalomas with patients is difficult and that physicians are often faced with a double-edged sword.
“If the doctor recommends ‘watch and wait,’ over time, that physician is bound to see an incidentaloma that turns out to be an aggressive cancer,” Dr. Brawley said. “However, if the doctor treats all incidentalomas aggressively, they will certainly end up seeing a patient harmed with what might be needless treatment.”
Dr. Braunstein said it is important to emphasize with patients just how common incidentalomas are and that most of them have no clinical significance. Physicians should explain that sometimes medical interventions, such as biopsies, can be just as harmful to patients, leading to significant morbidities or even death.
Dr. Rao recommended that primary care physicians hold a brief follow-up call with the radiologist before speaking with the patient to make sure both parties are comfortable with what to tell the patient and agree about whether a finding requires follow-up. If the patient needs further reassurance, the primary care physician can give the patient the name and phone number of the radiologist, who can discuss the findings of the imaging procedure in more detail.
In cases where a patient is still not comfortable with the physician's recommendation, Drs. Brawley and Braunstein agreed that it is perfectly reasonable to refer a patient to a specialist or encourage them to get a second opinion.
“Incidental findings are extraordinarily common and most of the time do not require any specific therapy,” Dr. Braunstein said. “One of the responsibilities of any physician will be to reassure the patient of that and remind them that you are not going to forget about [the incidentaloma], but that you do not want to do more harm than good.”