Abstract
We compared the treatment outcomes, toxicities and prognoses of patients with stage IE-IIE extranodal natural killer/T-cell lymphoma (ENKTL) treated with intensity-modulated radiotherapy (IMRT) or three-dimensional conformal radiotherapy (3DCRT). Newly diagnosed early-stage ENKTL patients (N = 173) were enrolled and received extended involved-field radiotherapy following induction chemotherapy. Patients were treated with 3DCRT (n = 98) or IMRT (n = 75). One-to-one matching of the IMRT and 3DCRT groups was performed through propensity score matching, which yielded 23 pairs of patients. The two groups achieved similar complete remission rates before and after radiotherapy (P > 0.05). All patients were followed up for a median of 41 months. The rates of local recurrence-free survival (LRFS, P < 0.001), progression-free survival (PFS, P = 0.003) and overall survival (OS, P = 0.003) were longer in the IMRT than 3DCRT group. In the matched patients, IMRT was still associated with superior LRFS (P = 0.024), but not with improved PFS (P = 0.113) or OS (P = 0.115). Multivariate analysis also suggested IMRT was a favorable independent factor for LRFS (HR = 2.230, P = 0.043), but not for PFS (P = 0.195) or OS (P = 0.116). Equivalent acute toxicities were observed for 3DCRT and IMRT; however, among stage II patients who had received cervical irradiation, the rate of late xerostomia was lower in the IMRT than 3DCRT group (38.5% vs. 66.7%, P = 0.046). Overall, IMRT yielded a better treatment response and local control than 3DCRT, and tended to reduce late xerostomia in patients with cervical irradiation, but failed to enhance OS. Thus, IMRT is recommended for the treatment of stage IE-IIE ENKTL patients.
Highlights
Extranodal natural killer/T-cell lymphoma (ENKTL) is a distinct clinicopathologic entity with invasive behavior [1,2]
intensity-modulated radiotherapy (IMRT) was superior to three-dimensional conformal radiotherapy (3DCRT) in its effects on the local recurrence-free survival (LRFS), progression-free survival (PFS), and overall survival (OS) rates (P < 0.001)
When the effects of confounding factors were eliminated with propensity score matching (PSM), the OS benefit was no longer apparent, suggesting that IMRT was only associated with better local control in ENKTL patients
Summary
Extranodal natural killer/T-cell lymphoma (ENKTL) is a distinct clinicopathologic entity with invasive behavior [1,2]. Earlystage ENKTL represents 70-90% of cases, the clinical management of early-stage ENKTL remains controversial. Radiotherapy (RT) is well acknowledged as the primary therapy for early-stage ENKTL patients [810]. Conformal RTs such as intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3DCRT) have replaced conventional two-dimensional radiotherapy (2DRT), and have been widely applied in clinical practice [11,12,13,14,15,16,17,18]. The four-year loco-regional control exceeded 80% in patients treated with IMRT or 3DCRT, and no severe toxicity occurred [19,20,21]. Because IMRT is an intensity-modulated technique, it has typically provided better dose coverage of organs at risk (OARs) than 3DCRT. Owing to its dosimetric advantage, IMRT significantly reduced the rate of parotid gland hypofunction and improved the quality of life
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