Italy: PET-CT in Metastatic Disease Detection

A recent study has suggested that PET-CT could replace bone scintigraphy for the detection of metastatic disease in children with soft-tissue cancer.

According to the study, published in the European Journal of Cancer, PET can identify metastatic disease not evident on standard radiology workup (SRW) in a small number of patients due to its higher ability to recognize lymph node and bone involvement. Chest CT is essential for detecting lesions in intrathoracic sites, which can be performed in a one-stop-shot routine examination or on a dedicated chest CT scan.

Initial staging of rhabdomyosarcoma is critical for prognosis and treatment. The standard radiology workup (SRW) includes magnetic resonance imaging, chest computed tomography (CT), and bone scintigraphy. However, the use of 18 Fluorine-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) (18F-FDG-PET/CT (PET-CT)) is increasing.

Considering the above, Federico Mercolini, Pediatric Hematology and Oncology Unit, Department of Pediatrics, Bolzano Hospital, Bolzano, Italy, and colleagues aimed to evaluate the impact of PET-CT in the initial staging of patients with metastatic rhabdomyosarcoma enrolled in the European protocol MTS2008.

For this purpose, two authors retrospectively reviewed the SRW and PET-CT reports that compared the number and sites of metastases detected. PET-CT and bone marrow aspirates/biopsies were compared for bone marrow involvement.

Among 263 metastatic patients enrolled from October 2008 to December 2016, 121 had PET-CT performed at diagnosis, and for 118 of 121 patients, both PET-CT and radiological reports were available for review.

Key Findings of the Study

• Among 263 metastatic patients enrolled from October 2008 to December 2016, 121 had PET-CT performed at diagnosis, and for 118 of 121 patients, both PET-CT and radiological reports were available for review.
• PET-CT showed higher sensitivity than SRW in the ability to detect locoregional (96.2% versus 78.5%) and distant lymph node involvement (94.8% versus 79.3%), but sensitivity was lower for intrathoracic sites (lung 79.6% versus 100%).
• For bone metastasis, PET-CT was more sensitive than bone scintigraphy (96.4% versus 67.9%).
• The PET-CT sensitivity and specificity to detect marrow involvement were 91.8% and 93.8%, respectively.
• The mean number of metastatic sites was 1.94 (range 0–5) with PET-CT and 1.72 (range 0–5) with SRW.
• In four patients (3.4%), PET-CT changed the staging from localized to metastatic disease.

"Our findings demonstrate that PET-CT could replace bone scintigraphy to study bone involvement," concluded the authors.

Reference

The study titled, "Role of 18F-FDG-PET/CT in the staging of metastatic rhabdomyosarcoma: a report from the European paediatric Soft tissue sarcoma Study Group," is published in the European Journal of Cancer.

DOI: https://www.ejcancer.com/article/S0959-8049(21)00448-2/fulltext