Racial Disparities in Disease Presentation, Treatment, and Response Rates of Follicular Lymphoma (FL) in the United States (US): Report From the National LymphoCare Study (NLCS).

Abstract 1381

Poster Board I-403

FL is the most common indolent lymphoma in the US but its incidence in African Americans (AA) and Hispanics (H) is lower than White (W) pts limiting our understanding of its natural history in those populations. In addition, AA and H pts are underrepresented in clinical trials raising questions as to whether current treatment paradigms in FL apply to these groups. The NLCS is a prospective, longitudinal multi-center, observational study that enrolled consecutive newly diagnosed FL pts from March 2004 through March 2007 and collected data on disease characteristics, demographics, treatment patterns, and outcome. In 2007, we were the first to report the impact of race on disease characteristics and treatment selection in 2,519 FL patients (Nabhan et al, ASH 2007, Abstract #367). Herein, we report a follow-up confirming our previous observations and detailing physician-reported response rates along with early results for progression-free survival (PFS).

As of 5/15/2009, 94 AA, 126 H, and 2478 W were enrolled. AA and H pts accounted for 3.4% and 4.6% of pts, respectively. To our knowledge, this represents the largest prospective cohort of AA and H pts with FL. Data collected included information on grade, stage, B symptoms, FLIPI, treatment choice, and response assessments as measured by the treating physician. Chi-square and Fisher's exact test were used as appropriate to assess the relationships between race, disease characteristics, and outcome.

More AA (26%) and H (22%) presented at <45 years of age compared to W (9%) (p<0.0001). While there was no statistical difference among the three races in disease grade, stage, or B symptoms, 49% of AA pts had poor-risk FLIPI compared to 34% of W pts (p=0.037). This difference was mainly due to lower hemoglobin values, higher LDH, and higher stage. No statistical difference was noted in FLIPI scores between W and H pts.

Similar percentage of patients were observed as an initial strategy among the 3 races (18%) while all others received some form of an intervention. The use of anthracycline-based regimens for initial treatment was more frequent in W pts compared to AA (65% vs 47%, p=0.008). The difference in anthracycline use persisted in poor-risk FLIPI pts. W pts with grade 1 or 2 FL were also more likely to receive anthracyclines than their AA counterparts (56% vs 38%, p=0.042). Too few grade 3 FL pts were available to draw meaningful conclusion for this subset. No major differences were noted between H and W pts in anthracycline use.

Despite differences in treatment, pts had similar response rates across racial categories. With a median follow-up of 37 months, 61% (n=1504) W, 57% (n=54) AA, and 63% (n=79) H had a complete or partial response to whatever treatment they received. For pts who received rituximab monotherapy, 61% (n=216) of W, 58% (n=7) of AA, and 36% (n=4) of H responded. For pts who received rituximab with chemotherapy, 78% (n=998) of W, 82% (n=41) of AA, and 80% (n=63) of H responded. The response to anthracycline-based regimens was comparable across the three groups. Longer PFS was observed in H compared to W and AA [median not reached vs 57 months for W (p=0.05) and 54 months for AA (p=0.02); p-values were obatained form Cox model controlling for FLIPI, histologic grade, and extranodal sites]. Comparing PFS for W, H, and AA treated with an anthracycline were consistent with the overall PFS results. However, the PFS advantage for H pts was not evident in chemo-treated individuals not receiving an anthracycline. AA and W pts did not differ in PFS.

The NLCS provides the largest prospective registry information on AA and H pts with FL. While the AA FL pts were younger and more likely to have higher risk FLIPI, they were less likely to receive anthracyclines than W pts. However, responses were similar among W, AA, and H pts regardless of treatment received. A longer PFS was observed in H pts compared to others but this was not observed in those who did not receive anthracyclines. Longer follow-up is required to determine whether differences in treatment and PFS impact overall survival.