PET/CT may bring hidden cancers in Li-Fraumeni patients to light

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Occult malignancies in patients with Li-Fraumeni syndrome have more difficulty hiding from whole-body FDG PET/CT imaging, according to results of a preliminary clinical evaluation in the March 19 issue of the Journal of the American Medical Association.

According to Judy E. Garber, MD, director of the Cancer Risk and Prevention Program at the Dana-Farber Cancer Institute in Boston, and colleagues, the goal of the study was to gather preliminary data with which to evaluate F18-fluorodeoxyglucose–PET/CT (FDG-PET/CT) imaging as a potential surveillance modality to detect early malignancies in asymptomatic members of LFS kindreds. All of the patients were asymptomatic and had normal physical examinations and lab values.

Because malignancies can arise at any age and at any site in Li-Fraumeni patients, finding a practical and effective screening strategy has been difficult, the researchers said.

Of 15 individuals, baseline FDG-PET/CT scan identified asymptomatic cancers in three (20 percent). Lesions identified in three patients had a high probability of being malignant on the basis of FDG uptake (score ≥4 on a five-point scale).

Two individuals had papillary thyroid cancers (stage II and stage III) and one individual had stage II esophageal adenocarcinoma. Imaging revealed asymptomatic malignancies in three of 15 patients with Li-Fraumeni syndrome and no history of cancer. No other patient had a lesion with an FDG uptake score greater than 2 (probably benign), the researchers noted.

Identification of the malignancies at an early stage allowed all three patients to undergo potentially curative treatment.

"These preliminary data provide the first evidence for a potential cancer surveillance strategy that may be worthy of further investigation for Li-Fraumeni patients with [syndrome]," the authors said.

The authors cautioned that concerns about radiation exposure and issues inherent to screening for cancer in high-risk patients require careful evaluation in future studies.

"FDG-PET/CT imaging has the potential to detect a wide variety of cancers at potentially curable stages," the authors concluded. "The use of an imaging technique that is effective in detecting cancer in the whole body with acceptable radiation exposure could potentially be considered for the screening of high-risk groups, such as [Li-Fraumeni syndrome] families, if confirmed in a larger study."