Human epididymis protein 4 may not be a reliable screening biomarker for detecting lung carcinoma patients.

Human epididymis protein 4 (HE4) acts as a protease inhibitor. It has been detected in the serum of patients with lung cancer patients and its utility for lung cancer screening was found in different studies. Nevertheless, little is known regarding the expression of HE4 in lung carcinoma subtypes. The aim of the present study was to investigate whether HE4 expression is a reliable marker for detecting any lung carcinoma subtypes, including small cell lung cancer (SCLC), non-small cell lung cancer (NSCLC) and adenocarcinoma (AC). In total, 141 lung carcinoma patients were enrolled in the study. Biopsy samples were obtained from bronchoscopic biopsy. The tumors were classified as SCLC (group 1, 54 cases) or NSCLC (group 2, 87 cases) based on histology and immunohistochemistry. The latter was sub-grouped as adenocarcinoma (group 2a, AC) and squamous cell carcinoma (group 2b, SCC). The immunohistochemical expression of HE4 was compared between the groups. The study revealed that the majority of the SCLC and SCC cases were devoid of HE4 (90.1 and 89.65%, respectively). Approximately 10% of cases had HE4 immune expression and the staining was focal and moderate throughout the tumor tissue. On the other hand, 78.8% of AC expressed HE4 and the staining was diffuse and strong. The overall HE4 expression in the lung cancer patients was 33.7%. In conclusion, the results of the present study have shown that HE4 is expressed in adenocarcinoma of the lung but it is not frequent in SCC and SCLC. The value of HE4 as a screening biomarker for lung cancer is limited but its presence exclusively in adenocarcinoma may provide new insight for targeted therapy.