[National variation in molecular diagnostics in metastatic lung cancer]

The objective of this study is to determine at a national level whether patients with metastatic non-small cell lung cancer (NSCLC) are adequately tested for EGFR mutations and ALK rearrangement, because targeted therapy is tailored to the results of molecular diagnostics.

Retrospective cohort study.

Data from all patients with metastatic non-squamous NSCLC diagnosed in 2013 or 2015 were identified from the Netherlands Cancer Registry, and coupled with data from the Netherlands national pathology registry (PALGA). Using information extracted from PALGA we determined what percentage of the tumours were tested for EGFR or KRAS mutations and ALK rearrangement, identified the variables that were associated with the performance of molecular diagnostics and investigated the differences between 48 laboratories.

A total of 6,619 patients were included (2013: n = 3,195; 2015: n = 3,424). In 2013, EGFR or KRAS testing was performed on 73.1% of the tumours (variation between laboratories 30.6-91.7%); in 2015 this was 78.9% (variation 40.0-91.0%). In 2013 49.5% of the tumours without EGFR or KRAS mutations underwent ALK testing (variation between laboratories 6.3-100%) and in 2015 ALK testing was performed on 77.4% (32.5-100%). In 2015, 6 and 7 laboratories tested significantly fewer EGFR and ALK tests, respectively, than the national average.

In 2013, molecular testing for EGFR and KRAS mutations and, in particular, for ALK rearrangement was suboptimal. EGFR and ALK testing was performed significantly more often in 2015. Despite this increase, there is room for improvement in a number of laboratories and hospitals, considering that some patients were possibly wrongly not eligible for targeted therapy.