Worse Outcomes With Transformed Indolent Lymphomas Versus De Novo DLBCL

—These investigators used SEER data to compare the outcomes of transformed indolent non-Hodgkin lymphomas with de novo DLBCL at a population level, a situation for which little data exist.

By Erin M. Burns, PhD, MSPH

The outcomes of transformed lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (t-LPL/WM) are inferior compared with de novo diffuse large B-cell lymphoma (DLBCL), emphasizing the need to include early experimental therapies for patients with transformed follicular lymphoma (t-FL) with early transformation who received prior chemotherapy, a recent study suggests.¹

“There is a paucity of data evaluating the outcomes of all transformed indolent non-Hodgkin lymphomas (iNHLs) with de novo DLBCL at a population level,” John L. Vaughn, MD, Division of Hematology & Oncology, NYU Grossman Long Island School of Medicine, New York, NY, and coauthors noted in Blood Cancer Journal. “We hypothesize that transformed iNHLs have an inferior survival compared to patients with de novo DLBCL.”

Study design and sample

This population-based cohort study identified data from 19,921 patients with iNHL using the Surveillance, Epidemiology, and End Results-17 (SEER-17) database, diagnosed in the United States in 2000 to 2015. Of these, there were

11,934 FL
4070 extranodal marginal zone lymphomas (MZL)
1779 nodal MZL
516 splenic MZL
1622 LPL/WM.

Follow-up through 2020 identified histologic transformation in 6.78% of splenic MZL, 5.55% FL, 4.05% nodal MZL, 2.22% LPL/WM, and 1.62% extranodal MZL.

Survival, prior chemotherapy, and early transformation

The highest 5-year relative survival rates were observed for de novo DLBCL (68%), followed by

transformed extranodal MZL (61%)
t-FL (58%)
transformed nodal MZL (56%)
transformed splenic MZL (54%)
t-LPL/WM (36%).

De novo DLBCL also had the highest 5-year overall survival (59%) and lymphoma-specific survival rates (68%). Multivariable analysis revealed significantly higher excess hazard rates for patients with t-FL (hazard ratio 1.42; 95% CI, 1.24–16.2; P<0.001) and t-LPL/WM (hazard ratio 1.65; 95% CI, 1.02–2.67; P=0.04) compared with de novo DLBCL.

The highest frequency of early transformation was observed among patients with t-FL (47%), followed by t-LPL/WM (42%), and transformed MZL (all subtypes, 36%). For patients with t-FL, early transformation was associated with worse survival (hazard ratio 1.34; 95% CI, 1.03–1.74; P=0.03).

Prior history of chemotherapy before histologic transformation was most frequent in patients with t-FL (50%), followed by t-LPL/WM (47%) and transformed MZL (38%). For patients with t-FL, prior chemotherapy was associated with worse survival (hazard ratio 1.89; 95% CI, 1.45–2.48; P<0.001).

Conclusions

“Our findings add to the growing body of literature on the epidemiology of histologic transformation of iNHLs and will serve as a guide to explore further research in tailoring the management based on the transformed iNHL subtype and the timing of histologic transformation,” the authors noted.

This study is limited by the lack of clinicopathologic patient-level data and the exact details of treatment regimens, which are not included in the SEER database.

“To our knowledge, this is the first comparative study to show that the outcomes of patients with t-LPL/WM were inferior compared to de novo DLBCL,” the authors concluded. “Additionally, the poor prognosis associated with early histologic transformation and receipt of prior chemotherapy in patients with t-FL underscores the need for early institution of experimental therapies in this high-risk subgroup.”

Published: December 30, 2024

Erin Burns has 9 years of academic research experience, including postdoctoral research in microbiology and photocarcinogenesis. She writes about various areas of science and medicine.

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