The aim of the article was to treat Pliss lymphosarcoma by means of Cytoreductive surgery to improve patient outcomes by taking into consideration the dynamics of Blood Auto-Proteolytic Activity (BAPA). In rats suffering from tumour proves to be obvious that higher the BAPA, more intensive is the process of invasive growth of tumour. Therefore, the performance of cytoreductive surgery is more reasonable when BAPA is at its minimal level, i. e. either at the early stage of tumour, though this may sound as a paradox. Removal of the tumour at the maximal level of BAPA will favour rapid development of a recurrent tumour. This can be explained by the fact that the remained cells tend to be more serious threat when BAPA level appears to be high.