P-1827. Clinical Significance of Indeterminate Anti–Hepatitis C Antibody Test Results in Cancer Patients

Abstract Background Cancer patients are screened for hepatitis C virus (HCV) infection using an anti-HCV antibody (Anti-HCV) test. However, the clinical significance of an indeterminate anti-HCV result is unknown. We sought to study the clinical significance of an indeterminate anti-HCV result in cancer patients.Figure.Patient flow chartAbbreviation: Anti-HCV, anti–hepatitis C antibodya Patients with undetectable HCV RNA in the absence of HCV treatment.b Patients with detectable HCV RNA or a history of HCV treatment.Table.Characteristics of cases and controls.Abbreviations: ALT, alanine aminotransferase; IQR, interquartile range; HBV, hepatitis B virus; HCV, hepatitis C virus.a Patients with indeterminate anti-HCV antibody results without proven HCV infection.b Patients with reactive anti-HCV antibody results with proven HCV infection.c Evaluation by an infectious disease or hepatology specialist. Methods We conducted a case-control study of cancer patients who were screened for HCV infection using ARCHITECT Anti-HCV (Abbot laboratories, Abbot Park, IL, USA) at our institution between October 2016 and July 2024. Patients were categorized as having indeterminate or reactive anti-HCV results. We collected information on patients’ demographics, cancer type and stage, type of anticancer therapy, co-infections (hepatitis B virus [HBV] or HIV), and management after anti-HCV testing. Cases had indeterminate anti-HCV results and undetectable HCV RNA in the absence of HCV treatment. Controls had reactive anti-HCV results and proven HCV infection (detectable HCV RNA or a history of HCV treatment). The characteristics of the cases and controls were compared using univariate and multivariate logistic regression analysis. Results Of the 112,180 patients who underwent anti-HCV screening during the study period, 114 (0.1%) had indeterminate anti-HCV results; of these patients, 101 had cancer and were analyzed further (Figure). Anti-HCV testing was repeated in 24 (24%) patients; most had non-reactive (n=11; 46%) or indeterminate (n=9; 38%) results. Of all 101 patients with indeterminate results, 98 (97%) did not have proven HCV infection (Table), but 3 (3%; all were men older than 60 years, 2 of them with hematological malignancy and 1 with a solid tumor) had HCV infection. Multivariate analysis showed that patients who were men (adjusted odds ratio [aOR] 2.22, 95% confidence interval [CI] 1.40-3.53, p< 0.001), older than 60 years (aOR 1.61, 95% CI 1.01-2.56, p=0.046),or who had HBV or HIV coinfection (aOR 3.13, 95% CI 1.21-8.11, p=0.019), or cirrhosis (aOR 6.67, 95% CI 2.05-21.69, p=0.002) were more likely to have proven HCV (controls). Conclusion Indeterminate anti-HCV results are uncommon in cancer patients and rarely represent HCV infection. This study provides predictors of proven HCV infection. Disclosures Harrys A. Torres, MD, Principal investigator for research grants from the National Cancer Institute, and Gilead Sciences: Grant/Research Support