# Survival Trends and Prognostic Modeling in ALK‐Positive Anaplastic Large Cell Lymphoma: A Population‐Based Study in the Brentuximab Vedotin Era

## TL;DR

This study shows that the drug brentuximab vedotin improved survival for a rare type of lymphoma, and a new model helps predict patient outcomes.

## Contribution

A novel random survival forest model for risk stratification in ALK+ ALCL patients in the brentuximab vedotin era.

## Key findings

- Survival improved in the post-brentuximab vedotin era with a 5-year OS increase from 59.3% to 72.3%.
- The RSF model identified age, stage, and radiotherapy as key prognostic factors with strong predictive accuracy.
- Patients were stratified into high-risk (49.3% 5-year OS) and low-risk (86.0% 5-year OS) groups using the model.

## Abstract

ALK‐positive anaplastic large cell lymphoma (ALK+ ALCL) is a rare subtype of peripheral T‐cell lymphoma with traditionally favorable prognosis. The introduction of brentuximab vedotin (BV) has significantly impacted treatment outcomes, but the long‐term survival trends and predictive factors for this population remain underexplored.

A total of 1548 patients diagnosed with ALK+ ALCL between 2004 and 2017 were identified from the Surveillance, Epidemiology, and End Results (SEER) database. Patients were categorized into two eras: pre–BV (2004–2010, n = 795) and post–BV (2011–2017, n = 753). Overall survival (OS) was compared between eras. A random survival forest (RSF) model was constructed to identify prognostic factors and stratify survival risk in the post–BV cohort.

OS significantly improved in the post–BV era (HR = 0.68, 95% CI: 0.58–0.81, p < 0.001), with the 5‐year OS increasing from 59.3% to 72.3%. The RSF model identified age, Ann Arbor stage, primary site, B symptoms, and radiotherapy as key prognostic factors, showing good discrimination with C‐indices of 0.775 (training cohort) and 0.728 (testing cohort). Notably, radiotherapy was found to be a protective factor. The model effectively stratified patients into high‐risk (5‐year OS: 49.3%) and low‐risk (86.0%) groups.

The introduction of BV has significantly improved real‐world survival in ALK+ ALCL. The RSF model enables individualized risk stratification and may support future precision treatment strategies.