Lung adenocarcinoma patients with ROS1-rearranged tumors by sex and smoking intensity

Background: ROS1 rearrangements (ROS1+) define a distinct molecular subset of lung adenocarcinomas. ROS1 + tumors are known to occur more in never-smokers, but the frequency and outcome of ROS1 positivity by sex and smoking intensity are not clearly documented. Patients and methods: This patient cohort study included all never- (<100 cigarettes lifetime) and light- (100 cigarettes-20 pack-years) smokers, and a sample of heavy-smokers. ROS1 + rates by sex and smoking intensity were compared within and beyond our study. Survival outcomes were analyzed using Kaplan-Meier curves and Cox proportional hazards models. Results: Of the 571 total patients, ROS1 + was detected in 24 (4.2%): 6.4% in men and 3.0% in women; 5.1% in never-, 5.7% in light-, and 1.8% in heavy-smokers (P=0.05). Among the 209 stage IIIB-IV patients, men had much higher ROS1 + rate (11.1%) not only than women (1.7%, P=0.004) in our study, but also than men (0.4%–1.8%) in 8 published studies (Ps = 0.0019–0.0001). ROS1+ rates were similar between never- (9.3%) and light-smokers (8.1%) and significantly lower in heavy-smokers (1.2%, P=0.017), a finding confirmed by 6 published studies (Ps = 0.041–0.0001). Overall survival of ROS1 + patients were significantly better than the ROS1- (P=0.023) mainly due to targeted therapy. Among patients who exhibited resistance to crizotinib, follow-up treatment of entrectinib and lorlatinib showed remarkable survival benefits. Conclusions: The ROS1 + rates were higher in men than in women, and similar in never- and light-smokers, more pronounced in stage IIIB-IV patients. Newer-generation ALK/ROS1-targeted drugs showed efficacy in a cohort of crizotinib resistant ROS1 + patients. These results, when validated, could assist efficiently accruing ROS1 + patients.