Latar Belakang: Tumor sel germinal mediastinum merupakan kelompok neoplasma gonad yangsensitif terhadap kemoterapi, namun agresif dan memiliki prognosis buruk. Penegakkan diagnosisdini yang tepat adalah hal yang penting dan salah satunya adalah dengan penilaian penanda tumoralpha fetoprotein (AFP) dan beta human chorionic gonadotropin (ßHCG).Metode: penelitian ini dilakukan dengan desain uji diagnostik dengan pendekatan potong lintangterhadap pasien tumor sel germinal nonseminoma mediastinum di RSUP Persahabatan sejakJanuari 2015 hingga Desember 2022 dengan mengukur kadar Alfa Fetoprotein dan HumanChorionic Gonadotropin serum dan dilakukan pemeriksaan histopatologi. Analisis data dilakukanuntuk menguji sensitivitas, spesifisitas, nilai duga positif, nilai duga negatif, akurasi diagnostik,dan analisis kurva receiver operating characteristic (ROC).Hasil: Dari total 362 subjek yang memenuhi kriteria inklusi, dari kedua penanda tumor AFP danßHCG didapatkansensitivitas 90,77% (IK 95% 80,98% - 96,54%), spesifisitas 97,98% (IK 95%95,65% - 99,26%), nilai duga positif 90,77% (IK 95% 81,61% - 95,61%), nilai duga negatif97,98% (IK 95% 95,77% - 99,05%), rasio kekerapan positif 45,4 (IK 95% 20,27 – 99,58), rasiokekerapan negatif 0,09 (IK 95% 0,04 – 0,2), serta nilai akurasi diagnostik sebesar 96,69% (IK95% 94,28% - 98,28%).Kesimpulan: Pemeriksaan kadar Alfa fetoprotein dan ßhuman chorionic gonadotropin memilikiakurasi 96,69%, sensitivitas 90,77% spesifisitas 97,98%, nilai duga positif 90,77%, nilai duganegatif = 97,98% dalam penegakkan diagnosis tumor sel germinal nonseminoma mediastinum

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Background: Mediastinal germ cell tumors are a group of gonadal neoplasms that are sensitive

to chemotherapy, but very aggressive and have poor prognosis. Early and correct diagnosis is

important, one of them is by measuring tumor markers in serum: alpha-fetoprotein (AFP) and

beta human chorionic gonadotropin (βHCG).

Method: This study was conducted with a diagnostic test with a cross sectional approach design

on patients with mediastinal germ cell tumors at RSUP Persahabatan from January 2015 to

December 2022, and also assessment of tumor markers alpha-fetoprotein (AFP) and beta human

chorionic gonadotropin (βHCG) serum and histopathology examination. Data analysis was

carried out to find the sensitivity, specificity, positive predictive value, negative predictive value,

diagnostic accuracy, and receiver operating characteristic (ROC)

Results: Of a total of 362 eligible subjects, the sensitivity was 90.77% (95% CI 80.98% -

96.54%), the specificity was 97.98% (95% CI 95.65% - 99.26%), the positive predictive value

was 90.77% (95% CI 81.61% - 95.61%), the negative predictive value was 97.98% (95% CI

95.77% - 99.05%), the positive likelihood ratio was 45.4 (95% CI 20.27 - 99.58), the negative

likelihood ratio was 0.09 (95% CI 0.04 - 0.2), and the diagnostic accuracy was 96.69% (95% CI

94.28% - 98.28%).

Conclusion: the sensitivity was 90.77%, the specificity was 97.98%, the positive predictive value

was 90.77%, the negative predictive value was 97.98%, and the diagnostic accuracy was 96.69%.