Patterns of survival and surgical treatment in lung cancer patients in Estonia by histologic type and stage, 1996-2016.

Lung cancer (LC) remains the most frequent cause of cancer death worldwide. We aimed to examine long-term trends in LC survival in Estonia by age, gender, histologic type and stage, with specific focus on surgical treatment. Data on all incident cases of LC diagnosed from 1996 to 2016 were obtained from the Estonian Cancer Registry. Logistic regression was used to examine receipt of surgical treatment in localized LC. Relative survival ratios (RSR) were calculated, and excess hazard ratios (EHR) of death were estimated by stage with gender, age, histology and period of diagnosis as independent variables. Among the total of 16,423 cases, squamous cell carcinoma remained the most common histologic type. The odds of receiving surgical treatment in localized LC increased significantly over time and were associated with age, gender and histologic type. Overall, the age-standardized 5-year RSR improved significantly from 10% in 1996-2002 to 16% in 2010-2016 (from 8% to 15% in men and from 15% to 20% in women). Larger survival gain was seen in younger patients, for non-small cell LC subtypes, and for surgically treated patients. For localized disease, the 5-year RSR increased by more than 20 percentage units, reaching 50% in men and 69% in women. For all stages, the adjusted EHR of death was significantly associated with age, histologic type and period of diagnosis. We observed a substantial improvement of relative survival, with considerable variations across patient groups. After adjustment for age, gender and histology, a significant survival increase over time was seen for all stages. The considerable survival gain observed for localized LC can largely be attributed to rapidly growing proportion of surgically treated patients. Further investigation of LC management practices, particularly the use of non-surgical treatment options is warranted.