FIELD: medicine. SUBSTANCE: method involves examining peripheral blood of the patient for determining blood platelets, eosinophils, segmented, stab and juvenile leukocytes number, hemoglobin, general protein and glucose level, general bilirubin concentration, erythrocyte sedimentation rate, blood color and prothrombin index, calculating diagnostic indices from known formulas. No or one diagnostic index being positive, or hemoglobin, blood platelets and erythrocyte sedimentation rate violating threshold value, invasive cancer case is to be diagnosed. Two or more additional positive indices being detected, mean tumor diameter, patient weight, blood monocytes contents and thymol test are to be additionally determined, diagnostic indices are calculated from known formulas. No positive values of diagnostic indices and mean tumor diameter relative to the threshold value being obtained, invasive cancer case is to be diagnosed. One or more positive tests being additionally obtained, general leukocyte population is to be determined as Ltot, blood platelets as BPtot, erythrocyte as Etot, segmented leukocytes as SLtot, Lymphocytes as Lmtot and monocytes as Mtot and circulating blood volume CBV for men equal to Weight 0.07 and for women as Weight 0.065, general population for given blood cells is calculated. Then relative values are calculated for Weight, Ltot, BPtot, Etot, SLtot, Lmtot and Mtot with respect to mean tumor diameter. No positive values relative to threshold value being found, invasive cancer is to be diagnosed. One or more positive values being determined, early stage pathology is diagnosed. EFFECT: enhanced accuracy of differential diagnosis. 6 tbl
