Key points in assessing the validity of a study claiming an association between gene variants and lung cancer

The frequency of the variants is higher than in the general population.
The variants reported are (probably) pathogenic, and not of unknown significance.
Lung cancer cases are not enriched in cases with a personal or family history of cancer associated with the incriminated genes. Should that be the case, the authors must take it into account in their statistical analyses.
Heterozygous variants are associated with susceptibility to disease in heterozygotes, and not only in homozygotes.