There is a long-time unmet need for a means to detect breast cancer (BC) using blood. Although mammography is accepted as the gold standard for screening, a blood-based diagnostic can complement mammography and assist in the accurate detection of BC in the diagnostic process period of early diagnosis. We have previously reported the possible use of thioredoxin 1 (Trx1) in serum as a novel means to detect BC. | Lee et al. BMC Cancer 2022 22 12 https s12885-021-09055-1 RESEARCH ARTICLE Open Access The blood level of thioredoxin 1 as a supporting biomarker in the detection of breast cancer Youn Ju Lee1 Young Kim2 3 Bo Bae Choi4 Je Ryong Kim5 6 Hye Mi Ko5 6 Kyoung Hoon Suh2 7 and Jin Sun Lee5 6 Abstract Background There is a long-time unmet need for a means to detect breast cancer BC using blood. Although mam- mography is accepted as the gold standard for screening a blood-based diagnostic can complement mammography and assist in the accurate detection of BC in the diagnostic process period of early diagnosis. We have previously reported the possible use of thioredoxin 1 Trx1 in serum as a novel means to detect BC. In the present study we validated the clinical utility of Trx1 to identify BC by testing sera from biopsy-confirmed cancer patients and women without cancer. Methods We have generated monoclonal antibodies against Trx1 and developed an ELISA kit that can quantitate Trx1 in sera. The level of Trx1 was determined in each serum from women without cancer n 114 as well as in serum from patients with BC n 106 and other types of cancers n 74 including cervical lung stomach colorec- tal and thyroid cancer. The sera from BC patients were collected and classified by the subjects age and cancer stage. In addition to the Trx1 levels of BC patients several pathological and molecular aspects of BC were analyzed. Test results were retrospectively compared to those from mammography. Each test was duplicated and test results were analyzed by ROC analysis one-way ANOVA tests and unpaired t-tests. Results The mean level of Trx1 from women without cancer was SD ng ml that of the other malig- nant cancer patient group was ng ml and that from the BC group was ng ml. The difference among these values was large enough to distinguish BC sera from non-BC control sera with a sensitivity of and specificity of AUC p Lee et al.