Radionuclide imaging of bone marrow metastases with a Tc-99m labeled monoclonal antibody to small cell lung carcinoma

The detection of metastatic disease confined to the bone marrow compartment has in the past been technically limited. We have identified excellent imaging of bone marrow metastases during the evaluation of a Tc-99m labeled monoclonal antibody (NR-LU-10 Fab) (NeoRx Corp., Seattle, WA). This occurred during a study to assess the monoclonal antibody's ability to detect sites of small cell cancer (primary and metastatic). The study by design compares areas seen by the monoclonal antibody scan with those found by standard staging methods in patients with small cell lung cancer. Standard staging included chest x-rays, bone scans, CT studies of the abdomen, and histologic examination of the bone marrow. Fifteen patients have been evaluated, four on two occasions, for a total of 19 monoclonal imaging studies. Metastasis to the marrow compartment was identified by the monoclonal imaging in all patients whose bone marrow biopsies were positive for small cell carcinoma, and it was primarily responsible for the eventual detection of extensive disease (marrow involvement) in one patient. Thus it appears that compartmental bone marrow imaging for metastatic disease is possible with immunoscintigraphy.