Unique prevalence of oncogenic genetic alterations in young patients with lung adenocarcinoma.

Background: Lung adenocarcinoma in the young is a rare entity, and the oncogenic genetic alterations (GAs) and clinical characteristics associated with this disease are poorly understood. Conversely, it has been demonstrated that young age at diagnosis defines unique biology in other cancers. For this report, the effects of young age on lung adenocarcinoma are reported.
Methods: The authors retrospectively screened 1746 consecutive patients who were diagnosed with stage I through IV adenocarcinoma between 2009 and 2015 and identified 81 who were aged 40 years or younger at diagnosis. The clinical and genetic characteristics of this younger population were analyzed.
Results: Of the 81 younger patients identified, 36 (44%) were men, 36 (44%) were never smokers, and the median age was 36 years (range, 26-40 years). Thirty-three patients (41%) harbored anaplastic lymphoma kinase (ALK) translocations, 24 (30%) had epidermal growth factor receptor (EGFR) mutations, and 2 (2%) had v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations. Rare oncogenic GAs also were studied in patients who had wild-type ALK/EGFR/KRAS adenocarcinoma, including 4 patients with HER2 mutations, 2 with Ret proto-oncogene (RET) translocations, and 2 with ROS proto-oncogene 1 receptor tyrosine kinase (ROS1) translocations. Notably, oncogenic GAs (P < .001), ALK (P < .001) and ROS1 (P = .033) translocations, and HER2 mutations (P < .001) were associated with young age, and a similar trend was observed for RET translocations (P = .108). Younger patients who had adenocarcinoma without GAs had a significantly worse prognosis compared with older patients without GAs (overall survival, 8.9 vs 16.4 months; P < .001) and patients with GAs (24.9 months; P < .001).
Conclusions: Younger patients with adenocarcinoma have a distinctly unique prevalence of oncogenic GAs. Comprehensive oncogenic GA screening is especially recommended for personalized medicine strategies in this population. Cancer 2017;123:1731-1740. © 2017 American Cancer Society.
(© 2016 American Cancer Society.)