Background: This study aimed to analyze pathologic characteristics, treatment, prognosis, and tumor epidermal growth factor receptor/anaplastic large-cell lymphoma kinase (EGFR/ALK) mutation proportion of non-small cell lung cancer (NSCLC) patients aged <40 years at diagnosis.
Methods: We retrospectively reviewed data of NSCLC patients diagnosed at Taipei Veterans General Hospital between June 2007 and December 2014, aged <90 years at the time of the diagnosis.
Results: We found 5051 cases of NSCLC, including 168 patients who were <40 years (younger group) and 4883 patients aged 40 to 89 years (older group). We found that the younger group had a significantly higher proportion of the EGFR mutation (22.6% vs 16.2%, p = 0.026) and the ALK mutation (4.2% vs 0.5%, p < 0.001) than the older group. Although the younger group included more stage IV patients (60.1% vs 49.6%, p = 0.002), it had a better overall survival (OS) rate (1 year: 73.7% vs 66.2%, p = 0.043; 5 years: 44.4% vs 33.7%, p = 0.004) (median survival time: 55 vs 26 months, p = 0.002). About the histologic subtype of NSCLC, the younger group presented less frequent cases of squamous cell carcinoma (4.2% vs 16.1%, p < 0.001), whereas the adenocarcinoma subtype was similarly frequent in the two groups (76.8% vs 76.5%, p = 0.924).
Conclusion: The OS rate in younger NSCLC patients was higher than that in the older NSCLC patients, despite the higher rate of stage IV NSCLC patients in the younger group. This survival benefit is most likely due to the higher proportion of the EGFR and ALK mutations and the corresponding tyrosine kinase inhibitor treatment.