Screening May Not Be Accurate Word to Represent the Cases Submitted to PET/CT Evaluation for Primary Tumor in a Patient Who Has Abnormal Serum Tumor Marker
Sunanta Chiewvit MD*, Saiphet Phasuk RN**, Savitree Surapako RN**, Wantana Juiklom BSc**, Pipat Chiewvit MD***
Affiliation : * Division of Nuclear Medicine, Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand ** National Cyclotron and PET Centre Chulabhorn Cancer Center Bangkok, Thailand *** Division of Diagnostic Radiology, Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
Objective : Determine the value of PET/CT in unknown primary cancer patient with high tumor marker and
negative study for clinical and conventional imaging.
Material and Method: A retrospective database review of 417 patients who received PET/CT between July
2006 and August 2007 in National cyclotron and PET center at Chulabhorn cancer center was done. Patients
were included in this study if the diagnosis were unknown primary cancer and rising tumor marker. Twelve
patients were included in this study. Data included age, gender, tumor marker rising, anatomical imaging
finding (CT and MRI), PET finding and clinical follow-up.
Results : Nine cases had normal PET/CT. This showed that PET/CT does not get more information than
conventional imaging. The PET scan showed positive in three cases, #5, #6 and #10. Two cases were false
positive, #5 and #6. Case #5 had clinical follow-up for one year and revealed to be normal. Case #6 PET
showed markedly glucose avid lesion at tumor thrombus but contrast CT confirm blood clot and the patient
was treat with wafarin and claxane. The follow-up clinical showed improvement. The high serum CA 125
explained by lung infarction caused the false positive. In case#10, the PET/CT suggested lung cancer at basal
segment of LLL.
Conclusion : Screening 18F FDG PET/CT is not appropriate in unknown primary with rising tumor marker and
normal conventional imaging is required.
Keywords : Keywords: Screening 18F FDG PET/CT, Rising tumor marker
