Many incidental findings spotted on MRIs, few turn out to be cancer

(Reuters Health) - Many people who get magnetic resonance imaging (MRIs) for a variety of common health problems may get an unexpected cancer scare that turns out to be a false alarm, a research review suggests.

Researchers focused on what they called “potentially serious incidental findings,” that is, accidentally discovered abnormalities that aren’t related to the symptoms that led a doctor to order the test and that may be serious. For example, a chest X-ray to look for pneumonia reveals an unexpected spot on the lung that may or may not be cancer.

Unexpected abnormalties like these, also known as incidentalomas, are turning up more often as more people get high-resolution scans that can spot irregularities that once went undetected.

Overall, about 4 percent of people had potentially serious incidental findings, the study team reports in The BMJ. This jumped to almost 13 percent when researchers also included incidental findings of uncertain potential seriousness.

Patients should “consider how they feel about the chances of a potentially serious incidental finding being detected, and that if such a finding is detected, that they may have to undergo more tests (some of which may be uncomfortable or even have some associated risk) before reaching a final diagnosis, and that most findings may not in the end turn out to be anything serious,” said senior study author Dr. Cathie Sudlow of the University of Edinburgh in the UK.

“For patients, it is difficult to know at the outset of the diagnostic journey whether or not the tests being performed are unnecessary,” Sudlow said by email. “We can only make this judgement in retrospect.”

For the current study, researchers analyzed data from 32 previously published studies that looked at the potential for serious incidental findings in more than 27,000 patients who had MRIs.

The prevalence of incidentalomas varied substantially depending on the type of scan.

For example, there were potentially serious incidental findings with 1.4 percent of brain MRIs, 1.3 percent of chest scans and 1.9 percent of abdominal MRIs.

About half of the potentially serious incidental findings were suspected malignancies.

Only about one in five of these incidental findings turned out to lead to a serious diagnosis after additional tests or procedures.

One limitation of the study is that researchers lacked long-term data on patients to determine if any of the potentially serious incidental findings might turn out to be precursors of tumors discovered years later, the authors note.

However, previous research suggests that 9 in 10 incidental findings aren’t serious after follow-up, Sudlow said.

“With the advancement of imaging technology, our sophisticated scans are now capable of identifying lesions that are either non-cancerous, or will never grow to cause a patient harm in their lifetime,” said Dr. Jack O’Sullivan, a researcher at Stanford University in California who wasn’t involved in the study.

“The discovery of a cancerous lesion that would benefit from appropriate treatment is a clear benefit of incidental findings,” O’Sullivan said by email. “The harms are related to potentially unnecessary anxiety, further testing and treatment of a lesion that will never grow to harm them.”

When patients are told they have an incidental finding after a MRI, they should ask their doctor what the odds are that the abnormal tissue would be harmful to their health, what side effects might result from any tests or treatments, and what happens if they do nothing to find out if the finding is actually cancer, O’Sullivan advised.

“This is a very personal decision,” Sudlow said, “People’s opinions vary widely on what they would want to do.”

SOURCE: The BMJ, online November 22, 2018.