Laterality and survival in mesothelioma: A SEER database analysis.

e20594 Background: Malignant pleural mesothelioma (MPM) is a highly aggressive and rare cancer type that carries dismal prognosis with a median survival of only 12 months. Often patients are diagnosed at advanced age and tend to have many co-morbid conditions. More precise prognostication should help physicians to decide on the best treatment approach for patients. Previous three studies suggest right sided involvement is associated with poorer prognosis. However, these were very small studies and estimates were not precise. We therefore decided to assess prognostic indicators, including laterality, using the large SEER database. Methods: Using SEER database, a total of 5064 cases diagnosed between 1975-2003 were included in this study. R software (4.0.5) was used. Prognostic indicators assessed included age, stage at diagnosis (distant versus regional/early), gender, and tumor laterality. We evaluated all-cause mortality using multivariate regression and introduced a competing risk regression to explore the association of clinical features and mesothelioma-related death. In analyses, we treated non-cancer related death as a competing factor. The prognostic significance of laterality was assessed at each stage of diagnosis. Results: The patients were predominantly male (81%), aged 60 years or older (79.1%) with right side predominance (58.9%). The overall median survival time was 8 months. The cumulative incidence of mesothelioma-specific death was 42% at 6 months and 62% at 12 months. In the multivariate analysis, male gender (HR = 1.23, p < 0.01), age 60 year or older (HR = 1.52, p < 0.01) and distant stage at diagnosis (HR = 1.2, p < 0.01) were independent predictors of shorter overall survival. In subgroup analyses of different stages, right sided mesothelioma was an independent predictor of mesothelioma-related death(HR = 1.14, CI 1.00-1.28, p = 0.042) in patients with regional/early-stage disease (Table) after adjustment for age and gender. When included all cohort with both early and late stages, there was no statistically significant association between laterality and all-cause mortality(HR = 1.02, CI 0.958-1.08, p = 0.61). Conclusions: Our study confirms that right-sided involvement is independently associated with increased risk of death in early stage/localized mesothelioma patients. The lack of association between laterality and survival in those with distant spread may be explained by the overall shorter survival in that group.[Table: see text]