Relapse localization in Danish pediatric patients with Hodgkin lymphoma

Abstract

Background

Pediatric Hodgkin lymphoma (pHL) is highly curable. However, a minority experience relapse and are subjected to toxic salvage regimens. Investigating the patterns of relapse could help to select the patients and/or the involved sites that would benefit from consolidating radiotherapy.

Material and methods

The Danish Childhood Cancer Registry was used to identify children <18 years with relapsed pHL from 1990–2018. The lymphoma volumes involved at diagnosis and at relapse were contoured on the patients’ original scans. Rigid image co-registration was used to merge the scans enabling a visual assessment of the anatomical relapse localization relative to the initially involved lymph nodes, and if irradiated, to the radiotherapy field.

Results

From 185 patients with pHL, 24 patients with relapse were available for analysis. All patients received combination chemotherapy and seven had consolidating radiotherapy. Relapses exclusively in initially involved sites occurred in 14 patients. Relapses exclusively in new sites were rare and only observed in three irradiated patients. Seven patients relapsed in both initially involved and new sites. The median time to relapse was 6 months (range 2–59 months), however, in-field relapses in irradiated patients occurred later (54 months, range 10–59 months). Neither risk group, initial bulky disease, early response, or metabolic activity seemed to be associated with the site of a later relapse.

Conclusion

The number of relapses were small, and conclusions regarding the selection of patients for radiotherapy could not be drawn. Relapse exclusively in initially involved sites were the most common, most often in the exact same initially involved lymph nodes. Hence, modern involved site radiotherapy, focusing on the initially involved lymphoma volume and minimizing the radiation doses to normal tissues, should be applied when consolidating radiotherapy is used in patients with pHL.

Keywords:

• Hodgkin lymphoma
• pediatrics
• relapse localization
• radiotherapy

Acknowledgments

We would like to acknowledge the clinicians and hospital staff who made it possible to collect the data for this study, especially Karen Ottosen Møller from the Department of Pediatric and Adolescent Health, Aarhus University Hospital; Akmal Safwat from the Department of Oncology, Aarhus University Hospital; and the Department of Pediatrics and Department of Oncology, Aalborg University Hospital.

Disclosure statement

Lena Specht is on advisory board and has received speaking honoraria from Takeda and Kyowa Kirin, and she has research agreements with Varian and ViewRay. The remaining authors indicate no conflict of interest.

Additional information

Funding

The work was supported by the Danish Cancer Society [grant number R248-A14714] and the Danish Childhood Cancer Society [grant numbers 2012-5 and 2015-9].