In addition, when the serum Trx1 level was measured in breast cancer patients in comparison with other cancer patients, the AUC (area under curve) value exceeded about 0.75, with the sensitivity and selectivity detected at more than 75% and 55%, respectively, in all cases, indicating that Trx1 is useful as a breast cancer-specific marker. The gene discussed is TXN; the disease is breast carcinoma.