Procalcitonin expression in patients with large cell neuroendocrine carcinoma of the lung

OBJECTIVE: Procalcitonin (PCT) has received much attention as a serum marker for bacterial infection. Elevated serum PCT is occasionally seen in severe trauma, heatstroke, and neoplastic diseases, including lung cancer with neuroendocrine component. RESULTS: In the present study, we evaluated PCT expression in the specimen of pulmonary neuroendocrine tumors, comparing large cell neuroendocrine carcinoma (LCNEC), carcinoid, and small cell lung carcinoma (SCLC). Pathological specimens of 10 LCNEC, 4 carcinoid, and 7 SCLC cases were evaluated with immunochemical staining of PCT. Clinical characteristics and serum levels of PCT and C-reactive protein were also evaluated. We observed positive PCT expression in 5 (50%) LCNEC and 2 (50%) carcinoid specimens that were surgically resected. Whereas serum PCT levels were not elevated in patients with PCT-positive carcinoid, two out of three LCNEC patients with high PCT expression in the tumor had elevated serum PCT levels that reflected disease progression. In patients with SCLC, PCT was not detected in the tumor or serum. This is the first immunohistochemical study of the PCT expression in the lung tumor specimens. We concluded that, in patients with LCNEC, high serum PCT levels may be indicative of disease activity and serve as a biomarker.