Early disease progression in patients with localized natural killer/T‐cell lymphoma treated with concurrent chemoradiotherapy

Prognosis of patients with localized nasal extranodal natural killer/T‐cell lymphoma, nasal type (ENKL) has been improved by non‐anthracycline‐containing treatments such as concurrent chemoradiotherapy (CCRT). However, some patients experience early disease progression. To clarify the clinical features and outcomes of these patients, data from 165 patients with localized nasal ENKL who were diagnosed between 2000 and 2013 at 31 institutes in Japan and who received radiotherapy with dexamethasone, etoposide, ifosfamide, and carboplatin (RT‐DeVIC) were retrospectively analyzed. Progression of disease within 2 years after diagnosis (POD24) was used as the definition of early progression. An independent dataset of 60 patients with localized nasal ENKL who received CCRT at Samsung Medical Center was used in the validation analysis. POD24 was documented in 23% of patients who received RT‐DeVIC and in 25% of patients in the validation cohort. Overall survival (OS) from risk‐defining events of the POD24 group was inferior to that of the reference group in both cohorts (P < .00001). In the RT‐DeVIC cohort, pretreatment elevated levels of serum soluble interleukin‐2 receptor (sIL‐2R), lactate dehydrogenase, C‐reactive protein, and detectable Epstein‐Barr virus DNA in peripheral blood were associated with POD24. In the validation cohort, no pretreatment clinical factor associated with POD24 was identified. Our study indicates that POD24 is a strong indicator of survival in localized ENKL, despite the different CCRT regimens adopted. In the treatment of localized nasal ENKL, POD24 is useful for identifying patients who have unmet medical needs.