Bone Scan Flare Phenomenon in Non-Small-Cell Lung Cancer Patients Treated With Gefitinib

Purpose: The bone scan flare phenomenon has been evaluated in various cancers in the presence of positive response to therapy. The aim of this study was to determine whether flare phenomenon occurs in non-small-cell lung cancer patients, especially adenocarcinoma in East-Asians, who respond dramatically and promptly to gefitinib. Methods: We retrospectively evaluated the radiographic and scintigraphic images of 125 lung cancer patients who had previous gefitinib treatment between July 2003 and October 2005. Those patients who had the first post-treatment scan done within 3 months and the second scan performed after 3 months after starting the therapy were included. New lesions or increased intensity observed on the first follow-up bone scan with improvement on the second one during gefitinib treatment was defined as positive for flare phenomenon. The results were correlated with clinical disease status. Results: Thirty-three non-small-cell lung cancer patients were included. Seven (21.2%) of them showed bone scan flare phenomenon. Of these seven, 5 had adenocarcinoma and 2 had unclassified non-small-cell lung cancer. Partial response was achieved after treatment in all these cases, and flare phenomena were detected between 29 and 77 days (median: 34 days) after treatment. Conclusion: The findings show that the flare is common during the first 3 months of gefitinib initiation; hence, a repeat bone scan should be reserved for later in the treatment course.