AbstractBackgroundHepatitis C virus (HCV) was reported to relate to polymorphous and frequent extrahepatic manifestation. Despite the limited studies, HCV viral oncoproteins may be implicated in breast cancer (BC) tumor aggressiveness. In a trial to elucidate a mechanistic link, this study aimed to investigate a mutant p53 and c-Myc oncoprotein expression levels in BC patients with and without HCV infection.MethodsA total of 215 BC patients (119 infected and 96 non-infected with HCV) were collected. ELISA was used for detection of anti-HCV antibodies, mutant p53, c-Myc, HCV-NS4, CEA, CA 125, and CA-15.3.ResultsHCV infection was related to BC late stages, lymph-node invasion, distant metastasis, high grades, and large size. HCV-infected patients had a significantly (P < 0.05) higher WBCs, ALT and AST activity, bilirubin CEA, CA125 and CA15.3 levels, and reduced hemoglobin, albumin, and RBCs count. Regardless of tumor severity, HCV infection was associated with significant elevated levels of mutant p53 (22.5 ± 3.5 µg/mL; 1.9-fold increase) and c-Myc (21.4 ± 1.8 µg/mL; 1.5-fold increase). Among HCV-infected patients, elevated levels of p53 and c-Myc were significantly correlated with elevated tumor markers (CEA, CA 125, and CA15.3) and HCV-NS4 levels.ConclusionsThis study concluded that HCV infection may be accompanied with BC severity behavior and this may be owing to elevated expression of mutant p53 and c-Myc oncoproteins.