Frequency and significance of bone marrow involvement by metastatic solid tumors

We have evaluated 3,620 bone marrow aspirates from 2,877 patients with solid tumors for the presence of clinically unsuspected metastasis. All aspirates were obtained from the iliac crest as part of the prechemotherapy workup and processed as smear and paraffin sections of the clot. Of the 2,877 patients, 263 (9.1%) showed metastatic tumor. Of these, metastasis was most frequent in neuroblastoma (48.2%), Ewing's sarcoma (35.5%), oat cell carcinoma (20.7%), prostate carcinoma (20.3%), breast carcinoma (19.6%), squamous cell carcinoma of the lung (15.7%), rhabdomyosarcoma (16.2%), and melanoma (6.8%). In most instances (92%), tumor cells were demonstrated simultaneously on both smears and clot sections. However, in lung and breast carcinoma, metastasis was noted more frequently in clot sections, while smears were superior for detecting both neuroblastoma and rhabdomyosarcoma. The prognostic significance of bone marrow involvement in 83 patients with state IV malignant melanoma scheduled for immunochemotherapy was investigated. In 39 patients (Group B, no bone marrow infiltration), the median survival was 59 weeks. In 44 patients (Group A, infiltrated bone marrow), the median survival was 6 weeks. Although bone marrow metastasis did not preclude response to immunochemotherapy, after 40 weeks only two patients of Group A were still alive, compared to 16 in Group B. This study demonstrates the usefulness of combining clot section and smear examinations for increased detection of unsuspected bone marrow metastasis and suggests the prognostic significance of bone marrow involvement in malignant melanoma.