Criteria for assessing the neuroendocrine phenotype and its incidence in nonsmall cell lung cancers

The neuroendocrine (NE) characteristics of 26 resected non-small cell lung cancers (NSCLC) were determined using immunocytochemistry. All 26 tumours expressed some features of NE differentiation, but the percentage of NE-positive tumours varied when the criteria for positivity, such as minimum staining intensity and proportion of stained cells, were adjusted. The incidence of NE-NSCLC was higher in these tumours (up to 100%) compared to that found by other groups when using their criteria for NE positivity, suggesting a genuinely higher incidence of NE-NSCLC in this geographical region. NE phenotype in these tumours did not correlate with survival.