Lung cancer survival and sex-specific patterns in Portugal: A population-based analysis.

Introduction: In Portugal, lung cancer (LC) is the first cause of cancer-related death and of death and disability combined. This study aims to analyze the overall survival (OS) and relative survival (RS) of patients diagnosed with LC in 2009-2011 by socio-demographic and tumor characteristics, and analyze sex-specific patterns.

Methods: We estimated 5-year OS using the Kaplan-Meier method and 5-year net survival through the RS framework. Cox regression modeling was used to determine the hazard ratio (HR) of death associated with each independent variable.

Findings: For the 11,523 cases analyzed, median 5-year OS was 264 days (95% confidence interval [CI]: 254.8-273.2), the cumulative OS was 13.6% and RS was 15.1%. Males had a lower median survival (237 days; 95% CI: 228.2-245.7) compared to females (416 days; 95% CI: 384.4-447.6) (p < 0.0001) and lower 5-year RS proportions (12.1% vs. 24.9%). RS progressively decreased with age (41.7% for age-group <40 to 7.2% for ≥80) and stage (66.6% for stage I to 2.4% for stage IV). As predictors of decreased survival, we identified male gender, increasing age >50, histologic types (squamous cell carcinoma, non-small cell lung cancer not otherwise specified, other unspecified and small cell lung cancer), and increasing stage. Compared to women, the risk of death in men was 37.7% higher (HR = 1.386; 95% CI: 1.295-1.484).

Conclusions: The differences between OS and RS were small, reflecting the high lethality of LC. Male gender and older age are factors related to poor prognosis. Histology also plays a role in survival prognosis and varies with gender, but the factor related to the worst survival is stage. Although the study reflects data from a decade ago, and major changes occurred in diagnosis, staging and treatment, particularly for advanced disease, as LC mortality is strongly correlated with late stage diagnosis, all efforts should be made to secure early diagnosis and improve survival prospects.