Control of tumor growth by pyridoxine restriction or treatment with an antivitamin agent.

The growth of 9A and 7316A Morris hepatomas was studied in pyridoxine (PN)-depleted and in pair-fed control Buffalo rats. Rat groups were fed the respective diets for 3 weeks, inoculated with 9A and 7316A tumor cells in both hind leg muscles, and killed after 21 and 41 days respectively. Another group was fed ad lib the PN-sufficient diet and similarly inoculated with 7777 hepatoma cells. In this instance tumors were let grow maximally to the extent that rats were practically unable to move and feed themselves. At this time ten animals were treated with L-penicillamine every other day for 9 days, leaving five (untreated) rats as controls. Rats pair-fed the PN-sufficient diet developed significantly heavier 9A and 7316A hepatomas with P less than or equal to 0.005 and P less than 0.001 significance levels, respectively. Treatment with the antivitamin agent extended significantly animal life span. Six rats lived for 8 days, three for 12, and one for 18 days. Four of the untreated rats died within 3 days, the fifth on the 8th day. These results demonstrate that PN restriction causes significant reduction in tumor weight and its in situ inactivation in vivo significantly extends the life of the tumor bearing animals.