While the incidence of breast cancer is higher than that of lung cancer, lung cancer continues to be a leading cause of death worldwide across both sexes, and some of the key statistics highlighting the devastating impact of lung cancer worldwide are illustrated in Figure 1.^1–3

Clinical impact of smoking

Epidemiological and clinical differences have been observed between never- and ever-smoking patients with non-small-cell lung cancer (NSCLC).^4,5 Never-smokers who develop cancer are more likely to be female and develop adenocarcinoma.⁶ In addition, differences between never- and ever-smokers have also been observed in the frequency of driver mutations.⁶ Epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK) gene mutations are consistently more common in never-smokers, while v-raf murine sarcoma viral oncogene homolog B1 (BRAF) and Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations are more common in ever-smokers.^6,7,8

Figure 3 shows the differences in oncogenic drivers between smoking and non-smoking populations,⁹ highlighting the impact that smoking has on the diagnosis and prognosis of lung cancer.

Prognosis

Additionally, smoking may impact the length and quality of survival of patients.¹⁰ Figure 4 highlights the differences in survival between never-smoking and ever-smoking populations.¹⁰

Never-smokers are more likely to be diagnosed with lung cancer at a later stage, with 47% of never-smoking patients receiving an initial stage IV diagnosis, compared with only 32% of ever-smokers.¹¹ The earlier diagnosis of ever-smokers may be an additional reason for why the overall survival between the two populations has not been found to have significant differences in many studies.⁴