¹⁸F FDG PET/ CT for planning external beam radiotherapy alters therapy in 11% of 581 patients

Background: 18F-FDG PET/CT (FDG PET/CT) used in radiotherapy planning for extra-cerebral malignancy may reveal metastases to distant sites that may affect the choice of therapy. Aim: To investigate the role of FDG PET/CT on treatment strategy changes induced by the use of PET/CT as part of the radiotherapy planning. ‘A major change of treatment strategy’ was defined as either including more lesions in the gross tumour volume (GTV) distant from the primary tumour or a change in treatment modalities. Methods: The study includes 581 consecutive patients who underwent an FDG PET/CT scan for radiotherapy planning in our institution in the year 2008. All PET/CT scans were performed with the patient in treatment position with the use of immobilization devices according to the intended radiotherapy treatment. All scans were evaluated by a nuclear medicine physician together with a radiologist to delineate PET-positive GTV (GTV-PET). Results: For 63 of the patients (11%), the PET/CT simulation scans resulted in a major change in treatment strategy because of the additional diagnostic information. Changes were most frequently observed in patients with lung cancer (20%) or upper gastrointestinal cancer (12%). In 65% of the patients for whom the PET/CT simulation scan revealed unexpected dissemination, radiotherapy was given – changed (n = 38) or unchanged (n = 13) according to the findings on the FDG PET/CT. Conclusion: Unexpected dissemination on the FDG PET/CT scanning performed for radiotherapy planning caused a change in treatment strategy in 11% of 581 patients

Routine Bone Marrow Biopsy Has Little or No Therapeutic Consequence for Positron Emission Tomography/Computed Tomography-Staged Treatment-Naive Patients With Hodgkin Lymphoma

Purpose To investigate whether bone marrow biopsy (BMB) adds useful information to [18F]fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) staging in patients with Hodgkin lymphoma (HL). Patients and Methods Newly diagnosed patients with HL undergoing a pretherapeutic staging that encompasses both PET/CT and BMB were included in this retrospective study. The pattern of skeletal FDG uptake was categorized as uni-, bi-, or multifocal (≥ three lesions). Clinical stage, risk assessment, and treatment plan were determined with and without the contribution of BMB results according to the Ann Arbor classification and the guidelines from the German Hodgkin Study Group. Results A total of 454 patients with HL were included of whom 82 (18%) had focal skeletal PET/CT lesions and 27 (6%) had positive BMB. No patients with positive BMB were assessed as having stage I to II disease by PET/CT staging. BMB upstaged five patients, assessed as being stage III before BMB; none of the 454 patients would have been allocated to another treatment on the basis of BMB results. Focal skeletal PET/CT lesions identified positive and negative BMBs with a sensitivity and specificity of 85% and 86%, respectively. The positive and negative predictive values of focal skeletal PET/CT lesions for BMB results were 28% and 99%, respectively. Conclusion A consistent finding of this study was the absence of positive BMBs in PET/CT-assessed stage I to II disease. The omission of staging BMB would not have changed the risk assessment or treatment strategy in this cohort of 454 newly diagnosed patients with HL. </jats:sec