Clear cell adenocarcinoma of the lung: a population-based study.

Background: Clear cell adenocarcinoma of the lung (CCAL) is a rare diagnosis with poorly understood clinicopathological characteristics and disease progression.

Methods: A population cohort study was conducted using prospectively extracted data from the Surveillance, Epidemiology and End Results database for patients with histological diagnoses of CCAL. Propensity-matched analysis was performed for survival analysis.

Results: A total of 1,203 patients with CCAL were included. The median overall survival (OS) for all patients was 19.0 months (95% CI 16.0-22.0 months). Data for 1-, 3-, and 5-year OS were 58.7, 37.3, and 27.7%, respectively. Log-rank analysis showed that the prognoses of CCAL patients were better than those with non-CCAL adenocarcinoma after propensity-matched analysis ( P <0.001). Cancer-directed surgery significantly improved median OS by almost 40 months (45.0 vs 5.0 months; P <0.01). Radiotherapy after surgery prolonged survival compared with patients who only received surgery (37.0 vs 17.0 months; P <0.01). Multivariate Cox analysis showed that older age (>65 years), larger lesions, and lymph node and distant metastases were independent prognostic factors for worse survival, while cancer-directed surgery was an independent protective factor. Five independent prognostic factors were identified and entered into the nomogram. The concordance index of the nomogram for predicting survival was 0.72 (95% CI 0.69-0.74). The calibration curves for the probability of 3-, 5-, and 10-year OS showed optimal agreement between nomogram prediction and actual observation.

Conclusion: CCAL is a rare pathology, and older age, larger lesions, metastases, and cancer-directed surgery were associated with prognosis. A prognostic nomogram was established to provide individual prediction of OS.