The clinical significance of cytology versus histology-based diagnosis in small cell lung cancer: a retrospective study

Objectives: The aim of this study was to investigate the clinical significance of cytology versus histology-based diagnosis among patients diagnosed with small cell lung cancer (SCLC).

Materials and methods: Retrospective analysis of medical records of 443 patients with histologically or cytologically confirmed small cell lung carcinoma (SCLC) was performed. All patients received platinum-based chemotherapy regimens. Survival data (overall survival) were compared between patients with histology or cytology-based diagnosis in the overall study population as well as after stratification of patients according to disease stage (limited or extensive) at the time of diagnosis.

Results: Distribution of demographics and clinicopathological characteristics among the two groups ("histology" and "cytology") was similar. No statistically significant differences in the survival curves between the "histology" and "cytology" groups were found in the overall study population (log rank test, p=0.237), as well as in the subgroup of patients with limited disease (log rank test, p=0.474). In contrast, patients with histology-based diagnosis had a statistically significant longer survival as compared to those with cytology-based diagnosis in the extensive disease subgroup (log rank test, p=0.031), but this association was not retained after adjusting the analysis for demographics and clinical characteristics via a Cox regression model (HR=1.18, 95% CI: 0.96-1.44, p=0.110).

Conclusion: The results of our study suggest that the type of diagnostic modality employed (histology or cytology-based) for the establishment of a diagnosis of SCLC may not have a significant effect on the overall survival of patients. Further studies are warranted to further investigate this important, yet rather unexplored, issue.