By Lisa Rapaport
Advanced imaging tests for many common health problems may catch something else entirely: abnormalities, known as “incidentalomas,” that can create anxiety about tumors but more often than not, don’t turn out to be cancer, a research review suggests
Incidentalomas are accidental discoveries unrelated to the diagnosis or symptoms that led a patient to undergo imaging. And they’re becoming more common as more patients get high-resolution magnetic resonance imaging (MRI) and positron emission technology (PET) scans, which can spot abnormalities that once went undetected.
“We know that the diagnosis of incidentalomas can cause patient anxiety and is likely to lead to further investigations and treatment, some of which will be unnecessary, and some of which will cause harm,” said lead study author Dr. Jack O’Sullivan of the University of Oxford in the UK.
“Almost all doctors that currently practice will tell you about an experience of an incidental finding,” O’Sullivan said by email.
For the current study, O’Sullivan and colleagues analyzed 20 previous research reviews that included a total of 627,073 patients.
Across the studies, the prevalence of incidentalomas varied substantially depending on the type of scan and location in the body, and so did the chance that these abnormalities might actually be cancer, researchers report in The BMJ.
For example, incidentalomas happened just 2 percent of the time with certain whole-body PET scans and with chest computed tomography (CT) tests to search for blockages in arteries in the lungs. In these situations, incidentalomas were often found in blood vessels.
With heart and chest CT scans, however, incidentalomas turned up 45 percent of the time in the throat, abdomen, spine or heart. CT colonoscopy, meanwhile, turned up incidentalomas outside the colon in 38 percent of cases and brain MRIs caught incidentalomas in the brain 22 percent of the time.
When patients had incidentalomas in the breast or ovary, they had the highest chance of these abnormalities turning out to be cancer after additional testing, the study found
About 42 percent of breast incidentalomas were malignant, as were 28 percent of incidentalomas in the ovaries and 11 percent in the prostate.
In other cases, the incidentalomas were almost always benign. For example, less than one hundredth of 1 percent of incidentalomas in the brain or adrenal gland were cancerous.
One limitation of the study is that researchers didn’t have enough data to determine the risk of incidentalomas or resulting cancer diagnoses for certain types of tumors and patients.
Even so, the current study adds to evidence linking advanced imaging to a risk of incidentalomas and offers fresh insight into the odds of this happening in various parts of the body, said Dr. Camilla Schalin-Jantti of Helsinki University Hospital in Finland.
“It is well known that continuous improvements in different radiologic imaging techniques that have happened over the last 10 years now also show smaller and smaller structures in our bodies that in a majority of cases are harmless,” Schalin-Jantti, who wasn’t involved in the study, said by email.
Incidental findings are also becoming more common as more patients get abdominal, chest and head CT scans performed in the emergency department, Schalin-Jantti added
One common situation involves abdominal pain, and CT scans that turn up incidentalomas in the adrenal glands just above the kidneys, Schalin-Jantti said. These have nothing to do with the source of pain and rarely turn out to be cancer.
Brain CTs are another source of incidentalomas, in this case in the pituitary gland, Schalin-Jantti said.
“In the emergency setting, CT scans are very useful in the diagnostic workup of patients suffering from acute severe symptoms,” Schalin-Jantti advised. “But they should not be used as a health check in persons having no symptoms, and we should avoid unnecessary imaging in order to reduce exposure to radiation, especially in young people.”