Introduction:Non-small-cell lung cancer outcomes are poor but heterogeneous, even within stage groups. To improve prognostic precision we aimed to develop and validate a simple prognostic model using patient and disease variables.Methods:Prospective registry and study data were analysed using Cox proportional hazards regression to derive a prognostic model (hospital 1, n=695), which was subsequently tested (Harrell’s c-statistic for discrimination and Cox–Snell residuals for calibration) in two independent validation cohorts (hospital 2, n=479 and hospital 3, n=284).Results:The derived Lung Cancer Prognostic Index (LCPI) included stage, histology, mutation status, performance status, weight loss, smoking history, respiratory comorbidity, sex, and age. Two-year overall survival rates according to LCPI in the derivation and two validation cohorts, respectively, were 84, 77, and 68% (LCPI 1: score⩽9); 61, 61, and 42% (LCPI 2: score 10–13); 33, 32, and 14% (LCPI 3: score 14–16); 7, 16, and 5% (LCPI 4: score ⩾15). Discrimination (c-statistic) was 0.74 for the derivation cohort, 0.72 and 0.71 for the two validation cohorts.Conclusions:The LCPI contributes additional prognostic information, which may be used to counsel patients, guide trial eligibility or design, or standardise mortality risk for epidemiological analyses.

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In this cohort of patients with NSCLC the SCS was not a clinically significant predictor of overall survival over and above basic patient and disease factors.

Background: Non-small-cell lung cancer (NSCLC) is a heterogeneous disease comprising not only different histological subtypes but also different molecular subtypes.Aim: To describe the frequency of oncogenic drivers in patients with metastatic NSCLC, the proportion of patients tested and survival difference according to mutation status in a single-institution study.Methods: Metastatic NSCLC patients enrolled in a prospective Thoracic Malignancies Cohort Study between July 2012 and August 2016 were selected. Patients underwent molecular testing for epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK) gene rearrangements, Kirsten rat sarcoma (KRAS), B-Raf proto-oncogene (BRAF) mutations and ROS1 gene rearrangements. Survival was calculated using the Kaplan-Meier method for groups of interest, and comparisons were made using the log-rank test.Results: A total of 392 patients were included, 43% of whom were female with median age of 64 years (28-92). Of 296 patients tested, 172 patients (58%) were positive for an oncogenic driver: 81 patients (27%) were EGFR positive, 25 patients (9%) were ALK positive, 57 patients (19%) had KRAS mutation and 9 patients (3%) were ROS1 or BRAF positive. Patients with an actionable mutation (EGFR/ALK) had a survival advantage when compared with patients who were mutation negative (hazard ratio (HR) 0.49; 95% confidence interval (CI) 0.33-0.71; P < 0.01). Survival difference between mutation negative and mutation status unknown was not statistically significant when adjusted for confounding factors in a multivariate analysis (HR 1.29; 95% CI 0.97-1.78, P = 0.08). Conclusion:In this prospective cohort, the presence of an actionable mutation was the strongest predictor of overall survival. These results confirm the importance of molecular testing and suggest likely survival benefit of identification and treatment of actionable oncogenes.

e19324 Background: KRASG12C mutations are present in 15% of non-small cell lung cancer (NSCLC) and have recently been shown to confer sensitivity to KRAS(G12C) inhibitors. This study aims to assess the clinical features and outcomes with KRASG12C mutant NSCLC in a real-world setting. Methods: Patients enrolled in an Australian prospective cohort study, Thoracic Malignancies Cohort (TMC), between July 2012 to October 2019 with metastatic or recurrent non-squamous NSCLC, with available KRAS test results, and without EGFR, ALK, or ROS1 gene aberrations, were selected. Data was extracted from TMC and patient records. Clinicopathologic features, treatment and overall survival was compared for KRAS wildtype ( KRASWT) and KRAS mutated ( KRASmut) patients, and between KRAS G12C ( KRASG12C) and other ( KRASother) mutations. Results: Of 1386 patients with non squamous NSCLC, 1040 were excluded for: non metastatic or recurrent (526); KRAS not tested (356); ALK, EGFR or ROS1 positive (154); duplicate (4). Of 346 patients analysed, 202 (58%) were KRASWT and 144 (42%) were KRASmut, of whom 65 (45%) were KRASG12C. 100% of pts with KRASG12C were smokers, compared to 92% of KRASother and 83% of KRASWT. The prevalence of brain metastases over entire follow-up period was similar between KRASmut and KRASWT (33% vs 40%, p = 0.17), and KRASG12C and KRASother (40% vs 41%, p = 0.74). Likewise, there was no difference in the proportion of patients receiving one or multiple lines of systemic therapy. Overall survival (OS) was also similar between KRASmut and KRASWT (p = 0.54), and KRASG12C and KRASother (p = 0.39). Conclusions: In this real-world prospective cohort, patients had comparable clinical features regardless of having a KRASmut, KRASG12C or KRASother mutation, or being KRASWT . Treatment and survival were also similar between groups. While not prognostic, KRASG12C may be an important predictive biomarker as promising KRAS G12C covalent inhibitors continue to be developed.