Cloning of human solid tumors in soft agar

Of 1,014 human solid tumors of various histologic types, 690 (68%) showed evidence of colony formation within 2 to 4 weeks. Tumors which grew particularly well were colon carcinoma (104/175), melanoma (134/155), lung carcinoma (62/85), breast cancer (100/140), ovarian carcinoma (50/67), and sarcoma (72/122). Histologic examination indicated that the colony‐forming cells retained functional and morphologic features similar to those of the original tumor. Plating efficiencies varied between 0.01% and 0.2%, and the numbers of colonies observed formed a direct linear correlation with the number of cells plated. Recovery of viable tumor cells was increased when enzymatic tumor dissociation was used rather than a mechanical method. A simplified, supplemented medium resulted in improved cloning efficiencies when compared to previously reported methods (Hamburger and Salmon, 1977 b ).