Relative contribution of cytological specimen type in the determination of lung cancer histologic identity – Analysis of one year's comparative data

We retrospectively evaluated the relative contribution of cytological specimens in identifying the histologic type of lung cancer. Seventy-four patients (50 male & 24 female) aged 63±8.9 years (mean±SD), eventually diagnosed to have lung cancer were studied. Diagnosis was established by either bronchoscopic or surgical biopsy.The spectrum of cytological specimens included: simple sputum smear (SP), bronchial washings (BW), post-bronchoscopy sputum (PB), brushing smears (BS) and transthoracic fine needle aspirates (FNA). The distribution of histologic types was as follows: Small Cell Lung Cancer (SCLC) 24 pts (32.4%), Squamous Cell Carcinoma 20 pts. (27%), Adenocarcinoma 14 pts. (18.9%), Undifferentiated Carcinoma 6pts (12.3%), Large cell Carcinoma 2 pts. (0.28%). Analysis of data showed that simple sputum cytology was diagnostic in 24.3% (relative contribution 66.6% for SCLC and 33.4% for NSCLC). Success rate of BW was 42% (almost equally partioned between SCLC & NSCLC 52% & 48% respectively). BS diagnosed 23% of lung cancer, of which 56.3% was the yield for adenocarcinoma. The contribution of FNA smears cannot be evaluated due to the very small sample size (only 2 patients which was successful in both).The overall contribution of cytology in the diagnosis among all types of lung cancer cases studied was 57 pts among a total of 74 (77%). We conclude that simple sputum cytology should not be neglected (having a diagnostic rate of 25% of patients) while the significance of BS in adenocarcinoma (56.3%) should be emphasized given its frequent peripheral location that does not allow obtaining tissue for histologic diagnosis.