P2.01-026 Distribution of Metastatic Disease in Survival Outliers with Stage IV Non-Small Cell Lung Cancer

Abstract

Lung cancer is the leading cause of cancer deaths among men and women in Canada. Many non-small cell lung cancer (NSCLC) patients have metastatic disease at the time of diagnosis, which is associated with poor survival outcomes. However, there appears to be a small subset of patients with advanced disease that live substantially longer than anticipated. Studies have examined the association of various clinical parameters, such as metastatic disease, with survival in cancer patients. Our study aims to determine the impact of metastatic disease burden and distribution on survival in survival outliers with stage IV NSCLC. Data on stage IV NSCLC patients diagnosed 1999-2011 was obtained from the Glans Look Lung Cancer database. Survival outliers were defined as patients who lived >5 years, or >2 standard deviations from mean survival (adenocarcinoma, 47.5 months; squamous cell carcinoma, 57.4 months); patients not meeting survival outlier criteria were defined as average survivors. Clinical characteristics such as age, gender, smoking history, and treatments were compared between survival outliers and patients with average survival. Metastatic disease was evaluated by comparing differences in organ sites, number of metastatic sites, and local versus distant metastases. Fisher's exact test was used to analyze categorical factors, and Wilcoxon rank-sum test was performed to study continuous factors. Statistical analyzes were implemented by R v3.3.0. 1803 stage IV NSCLC patients (1291 adenocarcinoma and 512 squamous cell carcinoma) were identified. In the adenocarcinoma group, there were 29 patients who lived >5 years, and 49 who lived >47.5 months. There were 13 squamous cell carcinoma patients who lived greater than 5 years and >57.4 months. Survival outliers tended to be younger, and had a smaller smoking history. Metastatic disease distribution differed significantly between adenocarcinoma and SCC survival outliers. Among adenocarcinoma patients, longer survival was associated with local metastatic disease (stage M1a), ≤1 site of metastasis at diagnosis, the presence of solitary bone metastasis, and the absence of liver metastasis (all p-values <0.05). In comparison, M1a disease, and the presence of solitary bone metastasis and solitary brain metastasis was associated with longer survival in SCC patients (all p-values <0.05). Survival outliers with local metastatic disease lived longer than patients with distant metastases. There were marked differences in the sites of distant metastases between adenocarcinoma and squamous cell carcinoma patients, and this was associated with differences in survival outcomes. The present study helps us better understand the role of metastatic disease distribution on survival, in hopes of determining important prognostic factors for lung cancer patients in the future.