The purpose of this study was to evaluate the possibility in the inhibitory effects of thymosin on S

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tumor growth in mice. On the basis of the tumor responses the following results were found (1) No improved therapeutic effects were obseved when p. o. administration of thymosin was combined with γ-ray irradiation. (2) When it was combined with cyclophosphamide the enhancement of anti-tumor effects was obvious. (3) Comparing p. o. with i. p. administration of thymosin

the same effect of inhibitory tumor growth was observed. (4) When the thymosin at the dose of 1.25~5 mg/kg were administerd

the slow down in relative tumor growth rate and increas in tumor inhibition rate were observed

but there was no obvious linear relationship between drug dose and tumor inhibitory response.