[A case of lung cancer with alkaline phosphatase flare phenomenon during gefitinib therapy].

A 79-year-old woman with adenocarcinoma of the lung almost fully obstructing the right main bronchus and with multiple bone and brain metastases was admitted to our hospital in March 2005. Irradiation was considered to be successful. Since subsequent vinorelbine chemotherapy was futile, it was changed to gefitinib in June. A week after gefitinib therapy, serum alkaline phosphatase (ALP) began to increase from about 400 IU/l to 1247 IU/l, to 3470 IU/l after two weeks, and up to 3527 IU/l after three weeks. The levels then decreased to within the normal range after nine weeks. ALP isozyme showed a peak composed of ALP2 and ALP3, and the levels of other enzymes (GOT, GPT, gamma-GTP) were normal. Hence, increased ALP was thought to be derived from the bones. The patient's performance status and metastases improved during this phenomenon. Bone scintigraphy findings one month after beginning gefitinib therapy worsened, but improved after four months. Bone ALP represents osteoblastic activity. We believe that in this case bone formation became dominant because of the favorable response to gefitinib therapy.