To provide a genetic testing method capable of accurately predicting a risk of occurrence of a cancer cell mass or the effect of a therapy in an early stage or after prognosis.

The genetic testing method for cancer includes: a step 10 for separating a buffy coat layer from a blood sample by centrifugation; a step 20 for separating a monocyte by density gradient centrifugation; a step 30 for extracting total RNA from the monocyte; a step 40 for synthesizing complementary DNA from the total RNA by reverse transcription reaction; a step 50 for carrying out a real-time PCR(RI-PCR) analysis for a cancer-relating gene; and a step 60 for carrying out a DNA microarray analysis for the cancer-relating gene by employing a DNA microarray as a nucleic acid microarray.