Ключевые слова: aged, analyzing, antigen, background, blood, blood test, cancer, care, checkup, diagnosis, disease, elder, elderly, exam, experiment, health, health care, hematology, hospital, illness, immunology, isolated, lab, laboratory, man, marker, medical, medical exam, medical technology, medical test, medicine, old, patient, plasma, prostate, prostate specific antigen, psa, research, sample, science, scientific, scientific experiment, serology, serum, specific, technology, test, tube, tumor, tumor marker,