Human tumor cloning: feasibility and clinical correlations.

The human tumor cloning system is a soft agar technique which allows the growth of human tumors in vitro. We report here our experience with culturing 2,365 patients' tumors in the system. Overall 1,844 (78%) have formed colonies in vitro. However, only 51% have formed greater than or equal to 30 colonies per 500,000 cells plated. Despite the limitations of inadequate growth for some tumors there are a number of clinical applications for the system, which are reported here. These include: (1) Use of the system to predict for sensitivity of an individual patient's tumor to a particular chemotherapeutic agent; (2) screening new anticancer agents to predict for in vivo activity; 3) monitoring patients' bone marrows for tumor involvement; and (4) use of the number of colonies which form in the assay as a prognostic factor for survival. All of these clinical applications are in their infancy of development and will require carefully designed prospective trials to determine the final place of the human tumor cloning system in the practice of clinical oncology.