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Should PET Scanning Replace Current Malignancy Screening Methods in Dermatomyositis?

Positron emission tomography with computed tomography was as effective as and easier than conventional cancer screening.

Because cancer is present in roughly 20% of patients diagnosed with dermatomyositis, most authorities recommend cancer screening at diagnosis and for some period thereafter. The most effective means of discovering malignancy in these patients is not yet established.

The authors collected data from three teaching hospitals in Barcelona, Spain, on the use of [¹⁸F]fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) screening for all patients with newly diagnosed inflammatory myopathy. They excluded patients with previous cancer, those with active infection that might affect scanning, and those for whom additional scans were medically contraindicated. PET scanning found a malignancy in 9 of 55 patients; 8 of the 9 had dermatomyositis. The positive and negative predictive values of PET scanning did not differ from results with traditional screening techniques, including physical examination, CT scans of the chest and abdomen, tests for serologic markers (CEA, CA-125, and prostate specific antigen), and, in women, pelvic ultrasound and mammography. The authors concluded that the use of the [¹⁸F]fluorodeoxyglucose PET/CT scan could take the place of all other testing and save patients' time.

Comment: These results are intriguing, but the conclusions are based on very few patients. The findings need to be replicated, and cost factors of the various tests should be considered in any future study. I am not yet willing to give up my traditional screening techniques and will continue to repeat the testing annually, for at least 3 years. I do not know if this is the optimal screening frequency, but until additional data are presented or published, I will advise my patients to follow this schedule.

— Jeffrey P. Callen, MD

Published in Journal Watch Dermatology September 3, 2010

Citation(s):

Selva-O'Callaghan A et al. Conventional cancer screening versus PET/CT in dermatomyositis/polymyositis. Am J Med 2010 Jun; 123:558.

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