highly significantP <0.0005
= 1 P = 0.02). Again there is no evidence of an interaction with batch (P = 0.19). Study 2 Table II and Figures 3 and 4 show the results of the second study which examined the dose response relationship of 4-OHA. There is a highly significant difference between control rats and those treated with 4-OHA, both in terms of tumour free survival (Logrank test for trend = 29.49 d.f. = 1 P <0.0005,) and overall survival (Logrank test for trend = 23.22 d.f. = I P <0.0005), confirming the results of the first study.