RESUMEN
Radionuclide therapy is widely used as an effective modality in the management of bone pain. The main indication for this treatment is symptomatic bone metastases, confirmed by bone scintigraphy. We present a case of small cell lung cancer [SCLC] stage T[4]N[2]M[1b], with a good metabolic response to systemic therapy and radiotherapy of the primary tumor and locoregional disease, which became metabolically less active and remarkably smaller in size [reduction to 1/6 of the original volume]. In spite of the good overall response, the patient developed a syndrome with severe bone pain and had progression in the bone marrow metastases, confirmed by [18]F-FDG PET/CT. The patient received [153]Sm-EDTMP treatment with a good clinical response. However, in the whole body bone scan with the therapeutic dose, there was no visual evidence of bone metastasis. Retrospectively, by drawing the region of interest, it was possible to identify one metastatic site. The possible mechanisms of the efficacy of this treatment modality, in this specific setting, are also discussed