An analysis of published studies has found that FDG-PET is less effective at diagnosing lung cancer compared to other kinds of benign lung diseases in geographic areas where those diseases are more common.
Examples of the kinds of diseases that could be misdiagnosed as lung cancer include fungal lung diseases such as histoplasmosis, coccidioidomycosis and blastomycosis, all of which reside in the soil. Histoplasmosis and blastomycosis are quite prevalent in the Mississippi, Ohio, and Missouri river valleys and in southern Ontario as well, while coccidioidomycosis is found in the American Southwest.
According to the researchers, these fungal lung diseases can result in inflamed lung nodules that can resemble cancerous lesions on radiographic images.
FDG-PET is recommended for the noninvasive diagnosis of lung nodules suspected of being cancerous. In this analysis, the researchers looked at lung cancer abstracts published over a 14-year period that involved the study of 8,511 nodules, 60 percent of which were malignant.
The Centers for Medicare & Medicaid Services in March 2013 issued a proposed decision memo to reverse a requirement that FDG-PET scans of patients with solid tumors be reported to the National Oncologic PET Registry. In a memo, CMS said it did not find evidence that FDG-PET improves health outcomes, but did determine that FDG-PET "changes physician management in this context. ... [T]he evidence shows that physicians are able to use the results of this diagnostic test in the treatment of patients with brain, pancreas, soft tissue sarcoma, small cell [of lung], thyroid, testis, or any other solid cancers." Three months later, CMS determined that it will pay for three follow-up scans instead of just one.
In previous analyses FDG-PET has been reported as being between 90 and 94 percent accurate in characterizing benign or malignant lung modules, but this analysis, published in the Sept. 24 issue of the Journal of the American Medical Association, found that the accuracy of FDG-PET varied widely from study to study, and that FDG-PET scans had more false positives and therefore were less accurate in areas where fungal lung diseases are more prevalent.
"The frequency of benign lesions in these geographic regions could lead to unnecessary biopsies or lung surgeries in patients," principal investigator Eric Grogan, M.D., an assistant professor of Medicine in the Institute for Medicine and Public Health at Vanderbilt, said in a statement. "However, some medical practices achieved greater test accuracy through robust reading methods, even in these regions."
The researchers concluded that the data doesn't support the use of FDG-PET to diagnose lung cancer in endemic regions unless the institution involved achieves test performance accuracy comparable to that found in nonendemic regions.
To learn more:
- see the article in JAMA
- see the announcement