THE EFFECT OF METHOTREXATE ON SPONTANEOUS MAMMARY ADENOCARCINOMATA IN FEMALE C3H MICE

Summary.-The effect of methotrexate on solid rodent tumours has been in-vestigated using the spontaneous mammary adenocarcinoma of the female C3H/Bts mouse. As these tumours exhibit a wide range of volume doubling times, cal-culations of tumour response to methotrexate must be related to doubling time. When methotrexate is injected into the tumour a dose-dependent tumour response is obtained. Systemic citrovorum " rescue " prevents methotrexate lethalities but reduces tumour response by a factor of 2. Methotrexate-treated tumours have an increased volume doubling time post treatment. THE FOLIC ACID antagonist metho-trexate (amethopterin, 4-amino- 10-methyl folic acid) has been used clinically in attempts to control a variety of tumours in man. There is, however, very little recorded information as to its effect on solid animal tumours, whether spon