The treatment of animal tumours and their metastases with 4-hydroxyanisole.

4-Hydroxyanisole (4-OHA) was administered to C57Bl/10J mice in which B16 melanoma or Lewis lung carcinoma had been implanted s.c. or i.m. The drug had the largest antitumour effect against B16 melanoma growing s.c. and a smaller antitumour effect against B16 melanoma or Lewis lung carcinoma growing i.m. In the treatment regimens where drug was administered only after tumour implantation, a significant reduction in number of spontaneous metastases and their incidence was observed. Again, the largest antimetastatic effect was observed for s.c. B16 melanoma with smaller effects observed for i.m. B16 melanoma or Lewis lung carcinoma. Experiments in which 4-OHA treatment was initiated after amputation of the primary tumour implanted in the tail confirmed that 4-OHA did have antitumour activity against disseminated tumour cells. The drug regimens studied to date produced significant delays in the appearance of spontaneous metastases in the lungs and significant increases in the life spans of the treated animals.