本研究旨在评估 CA-125 和 PET/CT 在特发性炎症性肌病 (IIM) 成人患者癌症检测中的诊断准确性。我们对 2003 年至 2020 年入组的成人 IIM 患者的单中心队列进行了回顾性研究从电子病历中提取 IIM 症状出现五年内进行的 CA-125 和 PET/CT 测试数据。评估的结果包括真阳性、假阳性、真阴性和假阴性结果。在 1432 名 IIM 患者中，在症状出现的前五年内对 205 名患者进行了 250 次 CA-125 测试，产生了假阳性结果率为 3.1%，假阴性率为 14.3%。大多数假阳性与子宫内膜异位症或子宫肌瘤有关，但通常会进行额外的医疗程序来调查假阳性结果。 PET/CT对139名患者进行了149次检查，假阳性率为5.5%，假阴性率为28.6%。淋巴结肿大和肺结节是假阳性的主要原因，而黑色素瘤、低期乳腺癌和前列腺癌是最常被漏诊（假阴性）的癌症。CA-125 和 PET 中假阳性和假阴性结果很常见/对新诊断特发性炎症性肌病的成年患者进行 CT 检测。了解这些不准确的原因可以帮助临床医生在患者护理期间做出明智的决定。© 作者 2024。由牛津大学出版社代表英国风湿病学会出版。版权所有。如需权限，请发送电子邮件至：journals.permissions@oup.com。

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).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.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).False positive and false-negative results are prevalent in 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.© The Author(s) 2024. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.