As reported by Olszewski et al in the Journal of Clinical Oncology, members of The Burkitt Lymphoma International Prognostic Index Consortium have developed an index—the Burkitt Lymphoma International Prognostic Index (BL-IPI)—that provides “robust discrimination of survival” among adult patients with Burkitt lymphoma.
The BL-IPI was developed in a derivation cohort from the retrospectively collected BL Real-World Evidence data set of adult patients treated at 30 U.S. sites between 2009 and 2018. The population consisted of 633 patients who received multiagent immunochemotherapy, including rituximab in more than 90%. Analysis was aimed at identifying candidate variables that showed the strongest prognostic association with progression-free survival.
The index was validated in an external data set of 457 patients pooled from a retrospective study from Australia, Canada, Denmark, Norway, and Sweden (2004–2017) and a specifically collected data set from eight institutions in the United Kingdom (2008–2019). All patients in the validation cohort received standard immunochemotherapy, including rituximab in more than 95%.
The variables considered for inclusion in the index in the derivation cohort consisted of age; sex; human immunodeficiency virus (HIV) status; Eastern Cooperative Oncology Group (ECOG) performance status; stage (I and/or II or III and/or IV); B symptoms; involvement of more than one extranodal site, bone marrow, or central nervous system (CNS); absence of MYC rearrangement; hemoglobin level; serum albumin; and serum lactate dehydrogenase (LDH) normalized to local upper limit of normal (ULN). Tumor size was not included due to low ascertainment in the validation cohort.
More than 75% of patients in both data sets had advanced-stage Burkitt lymphoma and abnormal LDH. Only 10% had disease historically categorized as low risk (stage I or II with normal LDH).
Development of Index in Derivation Cohort
In the derivation cohort, age ≥ 40 years, ECOG performance status ≥ 2, serum LDH > 3 times ULN, and CNS involvement were selected as equally weighted factors with independent prognostic value. The final BL-IPI identified groups with low (0 risk factors, 18% of patients), intermediate (1 factor, 36% of patients), and high risk (≥ 2 factors, 46% of patients). According to risk group, 3-year progression-free survival estimates were 92%, 72%, and 53% (P < .0001, C-statistic = 0.655 for discrimination) and 3-year overall survival estimates were 96%, 76%, and 59% (P < .0001, C-statistic = 0.667 for discrimination). The index discriminated outcomes irrespective of HIV status, stage, or first-line chemotherapy regimen.
Performance in Validation Cohort
In the validation cohort, the index categorized 15%, 35%, and 50% of patients as low-, intermediate-, and high-risk. According to risk group, 3-year progression-free survival estimates were 96%, 82%, and 63% (P < .0001, C-statistic = 0.648) and 3-year overall survival estimates were 99%, 85%, and 64% (P < .0001, C-statistic = 0.670).
The investigators concluded, “The BL-IPI provides robust discrimination of survival in adult [patients with] Burkitt lymphoma, suitable for use as prognostication and stratification in trials. The high-risk group has suboptimal outcomes with standard therapy and should be considered for innovative treatment approaches.”
Andrew M. Evens, DO, MSc, of Rutgers Cancer Institute of New Jersey, is the corresponding author for the Journal of Clinical Oncology article.
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