Abstract A73: Racial/ethnic differences in primary central nervous system lymphoma: A SEER-based estimate of incidence and survival rates among American blacks, American whites, Asian/Pacific Islanders and American Indians/Alaskan natives

The racial and ethnic associations of PCNSL have never been determined. Our clinical impression was that PCNSL was less commonly diagnosed in American Blacks (“Blacks”) than in American Whites (“Whites”) and rarely in Asian/Pacific Islanders (A/PI) and American Indians/Alaskan natives (AI/AN). We used SEER program data to determine if there was a racial difference in incidence and survival. The data are suggestive of a racial influence on PCNSL incidence and mortality.

Incident malignancies were classified using ICD-O, 2^ND Edition and specified NHL morphologies and stratified to those 20–49 years of age and those over 50. Subgroup analyses reflect the four SEER racial groups. Age-adjusted incidence rates were calculated to the 2000 U.S. standard million population and reported per 100,000 person-years (SEER*Stat software). 95% confidence intervals (CIs) were calculated based on properties of the Poisson distribution.

Among Whites the PCNSL incidence rate was 0.94 per 100,000 per year (95% CI 0.90–0.98); among Blacks the incidence was 1.10 per 100,000 per year (95% CI 0.98–1.22). The other subgroups had much lower PCNSL incidence rates. In patients aged 20–49 years at diagnosis PCNSL incidence in Blacks (IR=1.43, 95% CI 1.27–1.59) was twice that of similarly aged Whites (IR=0.72, 95% CI 0.68–0.76). For those above the age of 50 years, the incidence ratio between the two racial groups was reversed; 1.30 (95% CI 1.22–1.38) in Whites and 0.56 (95% CI 0.40–0.72) among Blacks. Survival for all races and all ages at 12 months, 2 years, and 5 years was 33%, 25%, and 16% respectively. Among all persons 20 years and older, survival at 12 months, 24 months, and 60 months among Whites was significantly higher than in Blacks. When stratified into groups of those 20 to 49 and those 50 or greater, only twelve month survival and 5 year survival was statistically different in the two racial groups (p=0.03; p=0.05, respectively).