FIELD : medicine.SUBSTANCE : proposed group of inventions relates to medicine. Method and kit for determining the presence of cancer in a subject, comprising determining the concentration of Hsp90α in a plasma sample of the subject. Disclosed is the use of EDTA-K2 as an anticoagulant when sampling plasma for the determination of Hsp90α.EFFECT : proposed group of inventions provides an increase in the sensitivity and specificity of cancer diagnosis in a subject in the range of Hsp90α concentrations from 56 to 82 ng/ml.11 cl, 15 dwg, 51 tbl, 8 ex