A quantitative method for assessing smoke associated molecular damage in lung cancers

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Lung cancer arises from tobacco exposure, but a significant portion occurs in never-smokers.
• Quantifying tobacco-induced molecular changes is crucial for understanding lung cancer etiology.
• Environmental tobacco smoke (ETS) contribution to lung cancer is challenging to assess.

Purpose of the Study:

• To develop and validate a quantitative method for assessing tobacco-related molecular damage in lung cancers.
• To differentiate molecular damage caused by tobacco smoke from other factors.
• To apply the method to various lung cancer subtypes.

Main Methods:

• Developed a quantitative assay combining tumor mutation burden (TMB) and molecular changes characteristic of tobacco smoke.
• Utilized maximum entropy (MaxEnt) to create an "F score" classifier for tobacco-related damage.
• Validated the F score against patient smoking histories, achieving 85-87% sensitivity, specificity, and accuracy.

Main Results:

• The F score assay analyzed lung adenocarcinoma (LUAD), lung squamous cell (LUSC), and small cell lung cancer (SCLC) datasets.
• Most LUSCs and SCLCs showed evidence of tobacco-related damage (negative F scores rare).
• LUADs showed varying degrees of damage, with a clear downward trend in never-smokers and reformed smokers.
• Bronchial carcinoids and LUADs with EGFR mutations typically lacked tobacco-related damage, while KRAS-mutated LUADs showed evidence of it.

Conclusions:

• A validated quantitative assay for assessing smoke-associated molecular damage in lung cancers has been established.
• This assay can differentiate molecular damage in lung cancers from smokers and never-smokers.
• The tool aids in understanding the molecular impact of tobacco exposure across different lung cancer types.