title: Radiation dose reduction for patients with extranodal NK/T-cell lymphoma with complete response after initial induction chemotherapy.
abstract: Previous studies have found that radiotherapy (RT) dose less than 50 Gy resulted in inferior outcomes for early stage extranodal NK/T-cell lymphoma (ENKTL). Nowadays, induction chemotherapy (CT) followed by RT consolidation is often used. For patients who get complete response (CR) after CT, whether RT dose can be safely reduced or not remains unknown. This retrospective study compared the survival outcomes between patients who received higher dose (>50 Gy) and lower dose (≤50 Gy) RT after CR was attained by CT. One hundred and forty four patients of early stage ENKTL got CR after induction CT and received RT consolidation. Thirty-one patients received lower dose RT (median 46 Gy, range, 36-50 Gy), and 113 patients received higher dose RT (median 56 Gy, range, 52-66 Gy). In univariate survival analysis, age >60, local tumor invasion, and non-asparaginase-based CT were associated with inferior progression-free survival (PFS) and overall survival (OS). However, there were no differences in PFS and OS between patients treated with higher and lower dose RT, which was confirmed in the multivariate survival analysis. Furthermore, reduced dose RT did not affect local control rate. Most common RT-related side effects were grade 1/2 mucositis and dermatitis, and the incidence rate of grade 3 mucositis or dermatitis was lower in patients treated with reduced dose RT (9.7% vs 15.0% for mucositis, and 6.5% vs 17.7% for dermatitis). In conclusion, this study found that RT dose could be safely reduced without compromising survival outcomes and further improved RT-related side effects. Prospective randomized controlled trials are warranted to validate our findings.
authors.affiliation: State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine; Department of Hematologic Oncology.
authors.forename: Liang
authors.initials: L
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine; Department of Medical Oncology.
authors.forename: Xi-Wen
authors.initials: XW
authors.lastname: Bi
authors.affiliation: State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine; Department of Hematologic Oncology.
authors.forename: Zhong-Jun
authors.initials: ZJ
authors.lastname: Xia
authors.affiliation: State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine; Department of Medical Oncology.
authors.forename: Hui-Qiang
authors.initials: HQ
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine; Department of Medical Oncology.
authors.forename: Wen-Qi
authors.initials: WQ
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine; Department of Radiation Oncology, Sun Yat-sen University Cancer Center, Guangzhou, People's Republic of China.
authors.forename: Yu-Jing
authors.initials: YJ
authors.lastname: Zhang
keywords: asparaginase; extranodal NK/T-cell lymphoma; prognosis; radiation-related toxicity; radiotherapy