Abstract
Bis-beta-diketonato complexes of titanium, zirconium, and hafnium were tested against autochthonous colorectal tumors in rats. The model was found to reflect the clinical situation most closely. Of the compounds tested, budotitane was the most effective in terms of decrease in tumor weight and number and in increasing the lifespan of the treated animals. The therapeutic efficiency was superior to that of 5-fluorouracil, which so far has been the drug with the best activity in patients suffering from colon cancer.