Trends in Survival of Patients with Burkitt Lymphoma Diagnosed in the USA: An Analysis of 3691 Cases
Authors: Costa Luciano J , Xavier Ana , Wahlquist Amy , Hill Elizabeth 
Published: October 2019

Abstract
Abstract 761

Background:
Burkitt lymphoma/leukemia (BL) is characterized by a highly aggressive clinical course, frequent association with HIV infection and poor treatment outcomes when treated with conventional chemotherapy regimens that are effective in less aggressive variants of non-Hodgkin lymphoma (NHL). Recent clinical trials and retrospective series have reported superior results in patients treated with highly intense multi-drug chemotherapy regimens, particularly when combined with the anti-CD20 antibody rituximab (chemoimmunotherapy). It is unknown whether the high rate of treatment success can be verified in a broader population and how the intensification of treatment, incorporation of rituximab, improvement in HIV treatment and improvements in supportive care changed the prognosis of newly diagnosed patients with BL.

Methods:
We utilized the Surveillance Epidemiology and End Results (SEER) database to describe time trends in the incidence (SEER-9) and outcomes (SEER-13) of newly diagnosed BL. Inclusion criteria for the outcomes analysis was diagnosis of BL (International Classification of Diseases-Oncology, Third Edition, ICD-O-3 codes 9687 and 9826) without any prior malignancy and year of diagnosis 1973–2008 with follow up information available. Cases where divided in two “eras,” 1973–2001 and 2002–2008, with the latter being expected to reflect the results of changes in treatment and supportive care. The impact of era on survival was described for different age groups, races and stages (limited or advanced). The impact of each of these factors on survival was assessed.

Results:
The incidence of BL in the USA changed from 0.5 cases / 1 million population*year in the 1970s to > 4.18 cases/ 1 million population*year in 2008. The large increase in incidence occurred in the second half of the 1980s and mostly among men, likely reflecting the epidemics of HIV infection. There were 1769 cases reported for the 1973–2001 era, and 1922 for the 2002–2008 era. Male patients corresponded to 2756 (75%) cases and females to 935 (25%) cases. The age distribution was 970 (26%) patients age 0–19 years, 897 (24%) age 20–39 years, 1047 (28%) age 40–59 years, and 777 (21%) age 60 or older. Stage was unknown in 1098 cases, limited in 908 (25%) and advanced in 1685 (46%). Most patients were white (n=3074, 83%), with 304 (8%) black patients, and 295 (8%) of other ethnicity. Overall, there was a marked improvement in survival after diagnosis of BL comparing eras, with 5 year survival estimates (95% CI) of 41% (39%-44%) in the 1973–2001 era and 54% (51%-56%) in the 2002–2008 era,(p<0.001, figure 1). Comparisons of 5 year survival rates indicated improvement from 71% to 87% among ages 0–19, from 34% to 60% for ages 20–39, from 27% to 47% for ages 40–59, and from 20% to 27% for ages 60 or older. Improved survival across era was seen in both genders, all races, in patients with advanced stage but not in patients with limited stage disease. In multivariable analysis utilizing Cox regression, diagnosis of BL in the 2002–2008 era (HR=0.76, 95% C.I. 0.65–0.87, p<0.0001) and being white (HR=0.67, 95% C.I. 0.53–0.84, p<0.0001) were associated with lower mortality. Older age (HR 1.03 for each additional year, 95% C.I. 1.03-1.03, p<0.0001) and advanced stage (HR 2.31, 95% C.I. 1.97–2.73, p<0.0001) were associated with higher mortality.

Conclusions:
There was marked improvement in the overall survival of patients with newly diagnosed BL in the last decade, affecting particularly young patients and patients with advanced disease. Outcomes of BL patients in the general population are inferior to the ones reported in the literature and specially poor for older and black patients. Safer and efficacious therapies are needed for older patients with BL along with improved access to modern chemoimmunotherapy for younger patients.

Disclosures:
No relevant conflicts of interest to declare.