In tissues obtained from patients undergoing gastrectomy or colectomy, sensitivity to mitomycin C (MMC), carboquone (CQ), and aclacinomycin A (ACR) was examined in 20 tumors (15 gastric, 5 colorectal) and in the adjacent normal mucosal tissues, using the in vitro succinate dehydrogenase inhibition test. The succinate dehydrogenase (SD) activity decreased to a greater extent in the tumor tissues than in adjacent normal tissues, at rates of 80% for MMC, 80% for CQ, and 90% for ACR. There were no correlations between SD activities of tumor and adjacent normal tissue, r = 0.157 for MMC, r = 0.435 for CQ, and r = 0.375 for ACR. Normal tissues were sensitive to MMC in 25 % of cases sensitive to MMC in the tumor tissues, 46% for CQ, and 38% for ACR. These results show that the antitumor effects of MMC, CQ, and ACR are relatively specific for tumor tissues and that the assay of chemosensitivity of normal tissues is meaningful for predicting the toxic effects of antitumor drugs on these tissues.
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