Utilization of a human tumor cloning system to monitor for marrow involvement with small cell carcinoma of the lung.

We have compared the sensitivities of two methodologies for determining bone marrow involvement by small cell lung cancer. These methodologies included histological examination of marrow aspirations and biopsies versus growth of tumor colonies in soft agar. There were four instances in which histological study of the marrow aspirate (and biopsy) revealed metastatic small cell lung cancer. All four of the specimens formed colonies in soft agar. Thirty-four of 37 histologically negative aspirations and biopsies) showed no growth in the soft agar system. However, three histologically negative specimens formed colonies in soft agar. The cells growing in these colonies were documented to be small cell lung cancer by histology and growth in nude mice. We conclude that small cell lung cancer metastatic to bone marrow will form colonies in soft agar. Additional study is needed to determine if the soft agar system is indeed more sensitive than routine histology in detecting small cell lung cancer metastatic to bone marrow.