Improved Assessment of Soft Tissue Sarcoma with PET
Researchers at the UCLA Jonsson Cancer Center evaluated the use of positron emission tomography (PET) to monitor patients with soft-tissue sarcomas undergoing treatment. The multi-disciplinary team published their findings in the February issue of Clinical Cancer Research.
This imaging modality was compared to the standard approach to monitor therapeutic response, CT imaging. Conventional imaging approaches qualify treatment response solely considering size-based evaluation. FDG-PET imaging, however, provides alternative dimensions for consideration, including metabolic activity. Clinicians can use this approach to determine if cells are still dividing after treatment.
Current approaches to assessment utilize RECIST (Response Evaluation Criteria in Solid Tumors). This is completed with either MRI or CT scanning both before and after treatment delivery. Scans are compared to assess changes in the size of the tumor.
The researchers investigated other modalities to assess disease because of experiences wherein tumors did not shrink in size but were completely dead when excised. An evaluation based on RECIST criteria would have suggested that the patient had not responded, when in fact, the tumor was “cured”. This hypothesis was investigated to ensure that patients continue treatment regimens that are efficacious.
Over forty patients were recruited to participate across a two year period, all had histopathologically verified high grade soft tissue sarcoma. The patients underwent FDG PET scanning and CT both before and after neoadjuvant therapy. Findings procured from each of the imaging modalities were compared to pathologic findings, the gold standard for disease response.
Study findings indicated that FDG-PET was much more strongly correlated with disease response than findings based on CT. In fact, CT identified only 20 percent of the patients who were responding to therapy. FDG-PET accurately identified all patients who responded 100 percent of the time.
This assessment approach is important for both assessment of neoadjuvant treatment, as well as long term disease evaluation. Additionally, this imaging approach may have applications for other solid tumors. FDG-PET provides additional information not gained from standard CT and MRI. Additional research may suggest that this type of imaging may be the best method to assess treatment response in patients with solid malignancies.
February 12, 2008 Related topics: Imaging, Diagnostic, Surgery, Hematology & Oncology