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. 2025 Apr 1;64(4):2115-2122.
doi: 10.1093/rheumatology/keae470.

Evaluating CA-125 and PET/CT for cancer detection in idiopathic inflammatory myopathies

XingYao Wang  1 , Jemima Albayda  1 , Julie J Paik  1 , Eleni Tiniakou  1 , Brittany Adler  1 , Andrew L Mammen  2   3 , Lisa Christopher-Stine  1   2 , Christopher A Mecoli  1
Affiliations

Evaluating CA-125 and PET/CT for cancer detection in idiopathic inflammatory myopathies

XingYao Wang et al. Rheumatology (Oxford). .

Abstract

Objective: This study aims to evaluate the diagnostic accuracy of CA-125 and PET/CT in detecting cancer among adult patients with idiopathic inflammatory myopathy (IIM).

Methods: We conducted a retrospective study of a single-centre cohort of adult IIM patients enrolled from 2003 to 2020. Data on CA-125 and PET/CT tests conducted within five years of IIM symptom onset were extracted from electronic medical records. The outcomes assessed included true-positive, false-positive, true-negative and false-negative results.

Results: Among 1432 patients with IIM, 250 CA-125 tests were conducted on 205 patients within the first five years of symptom onset, yielding a false-positive rate of 3.1% and a false-negative rate of 14.3%. Most false-positives were associated with endometriosis or uterine fibroids, but additional medical procedures were often carried out to investigate the false-positive results. For PET/CT, 149 tests were performed on 139 patients, resulting in a false-positive rate of 5.5% and a false-negative rate of 28.6%. Lymphadenopathy and lung nodules were the predominant causes of false-positives, while melanoma, low-stage breast cancer and prostate cancer were the most frequent cancers missed (false-negatives).

Conclusion: False-positive and false-negative results are prevalent in cancer antigen 125 (CA-125) and PET/CT testing for adult patients with newly diagnosed idiopathic inflammatory myopathy. Understanding the causes of these inaccuracies can aid clinicians in making informed decisions during patient care.

Keywords: cancer; cancer screening; dermatomyositis; immune-mediated necrotizing myopathy.

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Figures

Figure 1.
Figure 1.
2 × 2 Tables of true-positive, false-positive, false-negative, and true-negative results for CA-125 and ovarian cancer. A total of 205 patients underwent CA-125 testing; however, five patients were ommitted due to to an inability to verify the outcome
Figure 2.
Figure 2.
2 × 2 Tables of true-positive, false-positive, false-negative, and true-negative results for PET/CT and cancer. A total of 139 patients underwent PET/CT testing; however, two patients were ommitted due to an inability to verify the outcome
See this image and copyright information in PMC

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