Racial differences in incidence, outcomes, and genomic alterations in small cell lung cancer.

Abstract

8514 Background: While the incidence of small cell lung cancer (SCLC) has been decreasing in recent years, an increasing proportion of our patients are younger African American (AA) women. There have been no studies describing these changes as well its impact on outcome and potential genomic differences amongst white and AA populations. Methods: We maintain a clinical/genomic/pathological database of all patients with SCLC treated at our comprehensive cancer center starting from 1998. We compared the baseline characteristics and outcomes (Overall survival [OS] and progression-free survival [PFS]) between AA and white patients, and between females and males. In addition, we looked at genomic alterations in >350 cancer-related genes and compared the frequency and types of mutations in our study population. Results: A total of 917 patients with SCLC were included (median age 66 years, 486 female, 179 African American). Amongst the African American patients, 67.6% were female, a striking difference compared to the white population, where only 49.1% were women (P<0.001). In multivariable analysis, there was no association between gender or race with OS or PFS (P> 0.05). There was an increase in mutational frequency in AA women compared to both AA men and white patients. PIK3CA and KIT mutations were more frequent in females while APC mutations were more frequent in males (P=0.041 for all comparisons). There was a trend toward increased mutational frequencies in TP53, PTEN, and NOTCH1 in AA patients. The relative frequency of gene alterations is shown in the table. In univariable analysis, NOTCH1 mutation was associated with improved OS (HR 0.24 [0.06-0.96], P=0.04). Conclusions: In this large cohort of patients with SCLC followed over 2 decades, there was a striking 2-fold higher incidence of SCLC in AA females than in AA males, although there were no differences in OS or PFS by sex or race. Several genomic alterations occur in higher frequencies in AA patients and AA women, in particular, have higher mutational frequencies.[Table: see text]