Focal neuroendocrine differentiation in non-small cell carcinoma is not predicted by pre-operative routine investigation

Aims: Between 10 and 35% of resected non-small cell carcinomas of the lung show focal neuroendocrine differentiation. The significance of this is uncertain but recent studies have suggested that these tumours may be more responsive to chemotherapeutic agents than other non-small cell carcinomas. This study was undertaken to determine if focal neuroendocrine differentiation in surgically resected non-small cell carcinomas could be predicted in patients who had undergone traditional routine pre-operative diagnostic investigations. Methods: Sixty-six consecutive resections for non-small cell carcinoma were reviewed for the presence of focal neuroendocrine morphology or positive immunohistochemical staining with neuroendocrine markers. Pre-operative biopsy and cytology samples from these patients were then sought for similar assessment. Results: Ten of the 66 cases showed either morphological or immunohistochemical evidence of neuroendocrine differentiation. All 10 patients had undergone pre-operative investigation including bronchoscopy but in only four were pre-operative diagnostic samples obtained (two cytology and two biopsies). None of these specimens showed features to suggest the presence of neuroendocrine differentiation within the resected tumours. Conclusion: The presence of focal neurendocrine features in an unselected series of resected non-small cell carcinomas was not predicted by traditional pre-operative diagnostic investigations This indicates that focal neuroendocrine differentiation in patients with unresectable non-small carcinoma cannot be reliably identified for inclusion in clinical trials using traditional investigate approaches.