[Sensitivity test of antitumor drugs by the use of isotope]

A sensitivity test of antitumor drugs using primary shortterm culture with 3H-thymidine was performed on stomach cancer patients. Stomach cancer tissues, which were removed in the operating room, were cut into cubes of 1 to 2 mm. Thereafter, they were put on a stainless steel mesh which was placed in a small petri dish (40 X 15 mm) and they were moisted with the cultivating medium. An appropriate dose of antitumor drugs (MM-C, 5-FU, cytosine arabinoside) was added at the onset of cultivation and 3H-thymidine was further added 24 hours later. At the end of cultivation in a CO2 incubator for about 3 days, the specimens were homogenized in an ice-cold homogenizer with 5% trichloroacetic acid. DNA fraction of the specimens was extracted by Schmidt-Thannhauser method. The isotope activity in DNA fraction was measured in a scintillation counter and was represented as cpm/microgram DNA. Sensitivities of antitumor drugs can be determined by comparison between isotope incorporations into the specimens tested and those into control specimens. Bacterial and fungal contaminations were observed in primary stomach cancer tissues.