[Development of new in vitro chemosensitivity test using collagen gel droplet embedded culture and its clinical usefulness].

We developed a new in vitro assay for chemosensitivity test using collagen gel droplet embedded culture and image analysis. In this in vitro assay, we successfully minimized the cancer cell number required for culture to approximately 3-10 x 10(3) cells for each 30 microliters collagen gel droplet, obtained the sufficient growth of cancer cells using serum-free medium while suppressing the growth of fibroblastic cells, and measured the volume of cancer cells by eliminating the contaminating fibroblastic cells by an image processing technique. Anticancer effects of the in vitro assay showed a very good correlation with those of in vivo nude mouse assay using human cancer cell lines. The success rates of the in vitro assay for 141 surgical specimens of primary lung cancers and for 65 of primary breast cancers were 89 and 80%, respectively. The accumulated in vitro assay response rates of MMC, CDDP, VDS and VP-16 for primary lung cancers and of MMC, 5-FU and ADR for primary breast cancers were similar to the respective clinical response rates. These results suggest that this in vitro chemosensitivity test may be practically useful for clinical applications.