Clinical characteristics of the mixed form of neuroendocrine tumor in the lung: A retrospective study in 2501 lung cancer cases

BackgroundA neuroendocrine tumor (NET) is a special kind of epithelial tumor with predominant neuroendocrine differentiation, which arises throughout the body, including the lung. A subpopulation of lung cancer patients suffer from the mixed (combined) form of NET with components of non-neuroendocrine carcinoma. However, the clinical characteristics of the mixed form of NET are not well established. MethodsWe analyzed 2501 consecutive cases of primary lung cancer from 2009 to 2011. The diagnosis, histology, therapy, and outcome were collected. ResultsA total of 22 patients were enrolled. The occurrence rate of lung cancer was 0.9%. Neither gender (1.2% and 0.3% for male and female, respectively, P = 0.35) nor age (0.6% and 1.3% for patients aged 60 and >60, respectively, P = 0.13) was associated with the onset of this disease; however it has become more frequent in recent years (0.6% and 1.6% at the time and >2010 respectively, P = 0.03). This cohort of 22 patients had a median survival of 60.0 months (95% confidence interval: 14.3-105.6 months). Patients with metastatic disease (60 months and not reached [NR], P = 0.18) or a small-cell lung cancer component tended to have a shorter survival (35 months and NR, P = 0.16). Patients who underwent surgery had a significantly longer survival period (NR and 17.0 months, P = 0.001). ConclusionsA mixed form of NET in the lung is a rare disease. While stage and histology might influence prognosis, surgery is the critical factor for long-term survival.