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FDG-PET/CT leads pack for small-cell lung cancer staging


 

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For pretreatment staging of small-cell lung cancer (SCLC) the use of positron-emission tomography combined with CT was more sensitive compared with several other tests, according to a new report on a review of studies.

Overall, positron emission tomography using [F]-fluorodeoxyglucose as a radiotracer combined with CT (FDG-PET/CT) had greater sensitivity to detect osseous metastases than did bone scintigraphy or CT alone, according to Dr. Jonathan R. Treadwell, Ph.D., of ECRI Institute–Penn Medicine’s Evidence-based Practice Center in Plymouth Meeting, Pa., and colleagues. In addition, the researchers concluded that adding FDG-PET/CT to the protocol for patients who have undergone standard staging increased the sensitivity for detecting additional metastases. Data on endobronchial ultrasound were insufficient to draw any conclusions.

The findings generally line up with recent guidelines from the American College of Radiology (ACR) and American College of Chest Physicians (ACCP). In 2014, the ACR gave the highest rating of “usually appropriate” (with regard to staging SCLC) to FDG-PET/CT from skull base to mid-thigh, while bone scintigraphy was rated as “may be appropriate” and not necessary if PET/CT had been done, the researchers wrote. The 2013 ACCP guideline “suggested” FDG PET instead of bone scintigraphy for patients with limited disease, they added.

The researchers reviewed data from seven studies to assess the accuracy and effectiveness of several imaging modalities for the pretreatment staging of SCLC. The report was generated for the Agency for Healthcare Research and Quality (AHRQ) as part of its Comparative Effectiveness Review series, and is not an official AHRQ position, the researchers noted.

Combining FDG-PET with CT scanning has demonstrated even greater effectiveness at identifying malignant tumors and metabolically active metastases than has PET alone, because the CT allows for more localized anatomic detail, the researchers explained. “False negative scans usually result from non–metabolically active sites of tumor or from suboptimal quality studies,” they said, while false positives using FDG-PET are usually attributed to inflammation or metabolically active infection.

The meta-analysis included data on endobronchial ultrasound, which involves ultrasound to view structures inside and adjacent to the airway; bone scintigraphy, a less expensive planar molecular imaging technique; and CT alone.

Comparative evidence on pretreatment staging for SCLC is limited, according to the researchers. The data did not allow them to determine how FDG-PET/CT compared to other imaging in terms of specificity, and any type of imaging can yield false positives, they said. However, higher sensitivity alone can benefit patients in terms of improving patient selection for optimal therapy, sparing patients chemotherapy if not needed, and improving the prediction value of ongoing research, they noted.

“Although high-quality evidence may not be voluminous, I think most physicians would agree with the conclusion that a bone scan is not mandatory in the work-up of possible SCLC, if a PET/CT has been done,” Dr. W. Michael Alberts of the Moffitt Cancer Center in Tampa, Fla., said in an interview.

Cost might play a role in why the guidelines are being issued at this time, he noted, because “the initial work-up of the patient with suspected SCLC may prove to be quite expensive, and the elimination of a superfluous test may be a fiscal winner.” However, more research is needed in this area, particularly in the areas of including the order of pretreatment testing and the incorporation of new procedures and imaging modalities, he added. “Perhaps more intellectually challenging, however, might be the question of why SCLC is becoming less common, or why has improvement in treatment been so slow compared to NSCLC,” he added.

The researchers had no financial conflicts to disclose.

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