Study: PET/CT detects cancers when routine oncologic evaluations fail

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A whole-body PET/CT scan can detect cancer in patients with related neurologic complications more accurately than other commonly used tests, according to a study published online Jan. 11 in Archives of Neurology.

Routine noninvasive oncologic evaluations may be unrevealing as cancers detected in paraneoplastic neurologic disorders are frequently small and restricted to one anatomical site, according to Andrew McKeon, MD, and colleagues at the Mayo Clinic in Rochester, Minn.

“These standard evaluations include physical examination; CT of the chest, abdomen and pelvis; mammography in women; and testicular ultrasonography and prostate-specific antigen testing in men,” wrote McKeon.

The study analyzed the medical records of 56 consecutive patients with clinically suspected paraneoplastic neurologic disorders who underwent PET/CT after negative standard evaluations, including CT.

The researchers found that PET/CT detected abnormalities suggestive of cancer in 39 percent of the patients, in whom 18 percent had cancer confirmed histologically. Of these cancers, two were in the thyroid, one was in the tonsil, three were in the lungs, one was in the colon and three were cancerous lymph nodes with unknown primary cancer sites.

The detection facilitated early initiation of oncologic treatments and immunotherapy in nine of the ten patients with early-stage cancers and seven patients had cancer remission and five patients had improvements in neurologic symptoms after a median follow-up of 11 months, McKeon noted.

McKeon and colleagues favored PET/CT for initial oncologic evaluation of patients in whom a paraneoplastic neurologic disorder is strongly suspected.

“Elimination of whole body imaging with CT alone before further imaging with PET/CT could reduce radiation exposure and the total financial burden of testing,” McKeon added.