A case of lung adenocarcinoma with postoperative recurrence of multiple bone metastases that showed a gradual complete response to combined administration of erlotinib and zoledronic acid.

We describe a case of lung adenocarcinoma with multiple postoperative bone metastases that showed a gradual but complete response to combined administration of erlotinib and zoledronic acid. A 76-year-old man with moderately differentiated adenocarcinoma underwent a radical left upper lobectomy and mediastinal lymph node dissection. Three and a half years after the operation, serum carcinoembryonic antigen (CEA) was elevated and 18F-fluorodeoxyglucose positron emission tomography (18FDG-PET) revealed multiple bone metastases. Pretreatment evaluation of EGFR mutations in the resected primary adenocarcinoma specimen showed an L858R mutation in exon 21. Gefitinib was started as first-line treatment. However, evaluation 1 month after administration revealed progressive disease. Erlotinib was started as second-line treatment, and evaluation 1 month after administration revealed that the disease was stable. Administration of zoledronic acid was then begun with continuation of erlotinib. After 2 courses of zoledronic acid, the serum CEA level had not changed but the maximum standardized uptake values of each region uniformly decreased. Furthermore, the uptake of 18FDG completely disappeared after 6 courses. Subsequently, the serum CEA level continued to decrease and the disappearance of 18FDG uptake was confirmed after 10 courses (12 months after initiation of erlotinib administration). Our results suggest that the combined administration of both drugs is effective against bone metastases.We experienced a case of lung adenocarcinoma with postoperative recurrence of multiple bone metastases that showed a gradual but complete response to combined administration of erlotinib and zoledronic acid. Our results suggest that the combined treatment of both drugs is an effective therapy against bone metastases.