Cytology-based treatment decision in primary lung cancer: is it accurate enough?

Accurate distinction of lung cancer types has become increasingly important as recent trials have shown differential response to chemotherapy among non-small cell lung carcinoma (NSCLC) subtypes. Cytological procedures are frequently used but their diagnostic accuracy has been previously questioned. However, new endoscopic and cytological techniques might have improved cytological accuracy in comparison with prior findings. The aim of this study was to reassess cytological accuracy for diagnosis of lung cancer subtypes. A retrospective chart review of subjects who underwent fiberoptic bronchoscopy (FOB) for suspicion of lung cancer in 2007-2008, was undertaken. Reports of bronchoscopically derived cytological specimens were compared to those of histological material. Endoscopic findings and specific investigational techniques were taken into account. A total of 467 FOB with both cytological and histological diagnostic techniques were performed in 449 subjects. Patients consisted of 345 men and 104 women (median age, 65 yrs). Cytology proved malignancy in 157 patients. Cytologically diagnosed carcinomas were classified into squamous cell carcinoma (SqCC) in 56, adenocarcinoma (ADC) in 6, small cell lung carcinoma (SCLC) in 12, non-small cell lung carcinoma not otherwise specified (NSCLC-NOS) in 71, and unclassified carcinoma in 12. Cytology correlated fairly with biopsy specimens, as agreement was observed in 83% of SCLC, 100% of ADC, 74% of SqCC and 8% of NSCLC-NOS. Interestingly, 61% of cytologically identified NSCLC-NOS were classified as ADC by histology. Cytological accuracy improved in case of an endobronchial lesion, mainly for SqCC. These results indicate that cytological accuracy remains fair with regard to diagnosis of squamous and non-squamous lung cancer subtypes. Improvement of cytological accuracy is expected however with novel diagnostic strategies.