Improvement in population-based survival of stage IV NSCLC due to increased use of chemotherapy.

This study aimed to investigate which factors were associated with the administration of chemotherapy for patients with stage IV non-small cell lung cancer (NSCLC), and their relation to survival at a population-based level. All patients with NSCLC stage IV from 2001 to 2012 were identified in the Netherlands Cancer Registry in the Eindhoven area (n = 5,428). Chemotherapy use and survival were evaluated by logistic and Cox regression analyses, respectively. The proportion of patients receiving chemotherapy increased from 30% in 2001 to 48% in 2012. Higher rates were found among younger patients [multivariable odds ratio (OR(≤ 64_vs._≥ 75_years)): 1.8 (95%CI 1.6-2.1)], high socioeconomic status [OR(high_vs._low): 1.8 (95%CI 1.6-2.2)], no comorbidity [OR0_vs._≥ 2 : 1.5 (95%CI 1.3-1.8)], diagnosed in recent years [OR(2010-2012_vs._2001-2003): 2.0 (95%CI 1.6-2.3)] and adenocarcinoma [ORsquamous_vs._adenocarcinoma : 0.8 (95%CI 0.6-0.9)]. Having liver metastasis was associated with reduced odds (OR(liver_ vs._brain): 0.8 (95%CI 0.7-1.0). The variation between hospitals was large, up to OR 2.0 (95%CI 1.5-2.6). Median survival increased from 18 weeks in 2001-2003 to 21 weeks in 2010-2012 (log-rank p = 0.007), and was 35 weeks in patients with and 10 weeks without chemotherapy. The multivariable hazard of death reduced significantly over time [HR(2001-2003_vs._2010-2012): 1.1 (95%CI 1.0-1.2), HR(2004-2005_vs._2010-2012): 1.2 (95%CI 1.1-1.3)] and only remained significant for 2004-2006 after additional adjustment for chemotherapy [final multivariable model, HR(2004-2006_vs._2010-2012): 1.1 (95%CI 1.0-1.2)]. Besides, prognostic factors were having chemotherapy [final multivariable model: HR 0.4 (95%CI 0.4-0.4)], female sex [HRmale_vs._female : 1.1 (95%CI 1.0-1.1)], socioeconomic status [HR(intermediate_and_high_vs._low) both 0.9 (95%CI 0.9-1.0)], comorbidity [HR(unknown_vs._≥ 2): 1.3 (95%CI 1.2-1.5)], histology [HRother_vs._adenocarcinoma : 1.1 (95%CI 1.1-1.2)], and location of metastasis [range: 1.2 (HR(lymph_nodes_vs._brain)) - 1.6 (HR(liver_vs._brain))]. In conclusion, population-based survival increased due to increasing administration rates of chemotherapy. The administration of chemotherapy was affected by hospital of diagnosis and both patient and tumour characteristics. Identifying patients who benefit from chemotherapy should become a key issue.