Thioredoxin reductase (TR) activity is a novel tumor marker, and TR is also transiently increased when the body experiences inflammation and metabolic abnormalities. Thioredoxin reductase (TR) is a dimeric enzyme, a member of the pyridine nucleotide disulfide reductase family, which is widely expressed in Escherichia coli, yeast, liver, and tumor cells. Thioredoxin-reducing proteases provide reducing equivalents in the reduction reaction with thioredoxin as substrate and reduced nicotinamide purine dinucleotide phosphate. TR is an indicator that suggests abnormal lesions in the body at a much earlier stage than conventional tumor markers, and is closely related to drug resistance in tumors and the efficacy of tumor therapy after treatment. However, this indicator is affected by inflammation, metabolism and other factors, so its specificity is not high; therefore, TR is suitable for early screening of tumors, determination of drug resistance in tumor treatment, and evaluation of efficacy after treatment. Nowadays, most people think that it is related to liver cancer, pancreatic cancer, breast cancer, etc. However, a single elevation of TR is not necessarily cancer, so patients who have abnormal TR can consult the hospital for treatment under the guidance of the doctor.