A population-based study describing characteristics, survival and the effect of TKI treatment on patients with EGFR mutated stage IV NSCLC in the Netherlands.

Introduction: Since 2011, treatment guidelines advise targeted therapy (tyrosine kinase inhibitor, TKI) for patients with activating epidermal growth factor receptor (EGFR) mutations (EGFR+) in non-small cell lung cancer (NSCLC). We describe characteristics, first line treatment and survival of patients diagnosed with EGFR+ NSCLC in a European population, focussing on age, gender and trends over time and compare to the whole group and EGFR-.

Methods: All patients with non-squamous NSCLC stage IV, diagnosed 2011-2018, were identified from the population-based Netherlands Cancer Registry (N = 31,291).

Results: Among all, 7.0% were registered to be EGFR+, with highest prevalence in females <40 years (16%). Median overall survival (OS) ranged from 3.5 months in the EGFR- group >65 years to 23.6 months in the EGFR+ group <50 years treated with TKI. Over time, OS for the whole group increased by 0.6 months, of which 33% due to TKI treatment in EGFR+. The increase was strongest in females <50 years, where median OS almost doubled to 12.4 months. In the EGFR+, multivariable hazard of death was most strongly associated with the use of TKI (HR 0.45(0.41-0.49)). Of the patients with EGFR+ this space need or not, 71% received TKI treatment. Being young reduced the hazard of death (HR 0.71(95%CI:0.59-0.85)) irrespective of treatment, while male gender increased the hazard of death (HR 1.22(95%CI:1.11-1.33)).

Conclusion: At population level, TKI treatment in patients with non-squamous NSCLC stage IV EGFR+  has very strong beneficial effects on outcome. Of the improvement in OS that was made over the years for the whole group, about one third seems to be attributed to TKI treatment in EGFR+ patients.