Poor lifestyle choices like tobacco-chewing and smoking are apparent risk factors for certain types of cancers. However, there are numerous cancers that are not associated with any obvious risk factors, suggesting that there are inherent genomic patterns that make people susceptible.

In a bid to understand what causes lung cancer in never smokers, scientists at the National Institutes of Health analyzed the genomes of over 200 patients with lung cancer who had not yet undergone therapy and had no history of smoking. The analyses of the somatic copy number changes revealed three distinct molecular subtypes of mutational patterns in never smokers that contributed to lung cancer.

These mutational subtypes, which were named piano, mezzo-forte, and forte, were mostly associated with endogenous DNA damage.