Evaluation of PET scan in small cell lung cancer

Abstract

7214 Background: Small cell lung cancer remains a major health concern. Prognosis, survival, and treatment options correlate with stage at diagnosis. We hypothesize PET scanning may have a role in the staging procedure of patients with small cell lung cancer. Methods: A retrospective chart review of all patients between 1998–2003 diagnosed with small cell lung cancer was performed. Those who received a PET scan as part of the initial evaluation were reviewed and comparison was made against CT scanning and MRI imaging. Follow-up imaging and clinical outcome were used to evaluate any areas of disagreement between imaging. Results: A total of 116 new patients with small cell lung cancer were reviewed. 44 patients (44/116) received a PET scan. Sensitivity of PET imaging was 100%. Agreement between PET imaging and standard imaging for limited and extensive stage disease was 80% (35/44). Five patients were diagnosed with limited stage disease instead of extensive disease based on PET results. CT scan suggested adrenal metastasis in 4 patients, and opposite lung lesions in another, but the PET scan was not hypermetabolic. All but one (who was lost to follow-up) were treated as limited stage disease with concurrent radiation and chemotherapy. The four who remain have had survival and response suggestive of limited stage disease (alive at 6 months, 18 months, 32 months, and 3 years). Two patients were increased from limited to extensive stage by PET scan results, one survived 9 months and the other is 5 months into therapy. One patient had a biopsy proven false positive PET finding of lymphoid hyperplasia in the nasopharynx that would have increased the stage to extensive. PET scan missed diffuse liver metastases in one patient (false negative), who was staged with limited disease. PET scan was insensitive to detect brain metastasis (40% sensitive), although this did not change the patients' stage. Conclusions: As in non-small cell lung cancer, changes in the adrenal glands seen on CT scan may be difficult to interpret. These results suggest PET can clarify incidental findings of CT scan imaging. A PET scan may be helpful to insure patients with small cell lung cancer are accurately staged and offered appropriate treatment. No significant financial relationships to disclose.