Clinical Outcome And Dosimetric Analysis Of Radiotherapy For Patients With Waldeyer Ring Diffuse Large B-Cell Lymphoma

Part Ⅰ:Treatment and Prognosis of Patients with Waldeyer Ring Diffuse Large B-Cell LymphomaPurpose:To evaluate the clinical features and treatment outcomes of patients with Waldeyer ring DLBCL (WR-DLBCL).Methods and Materials:Two hundreds patients with WR-DLBCL treated between 2000 and 2013 were retrospectively reviewed in the study. Fifty patients had stage I disease,125 patients had stage II disease and 25 patients had stage III and IV diseases. Most patients received 4-6 cycles of CHOP or R-CHOP chemotherapy with or without involved-field radiotherapy.Results:Patients with WR-DLBCL presented with young men, a large proporation of early stage disease, low frequency of B symptoms and elevated lactate dehydrogenase (LDH), good performance status, and a low-risk score according to the international prognostic index (IPI). With a median follow-up time of 40 months, the 5-year overall survival (OS), progression-free survival (PFS) and locoregional control (LRC) rates for the whole group were 78%,72% and 87%. On univarable analysis, age, bulky disease, stage, LDH and IPI were significant prognostic factors for OS, whereas ECOG score and cervical nodal involvement were prognostic factors for PFS and LRC. On multivarable analysis, age and stage were independent prognostic factors for OS and LRC, whereas only age was an independent prognostic factor for PFS. In patients with early stage disease, combined modality therapy resulted in a significantly better OS (86% vs.70%), PFS (84% vs.58%) and LRC (97% vs.66%) rate than chemotherapy alone.Conclusion:The current results indicated that WR-DLBCL have distinct clinical features and favorable prognoses. Combined modality therapy resulted in higher survivals and LRC in patients with early stage disease.Part 2:Role of Radiotherapy for Early Stage Waldeyer Ring Diffuse Large B-cell Lymphoma in the Era of RituximabPurpose:To evaluate the role of consolidation radiotherapy following chemotherapy for patients with early stage Waldeyer ring DLBCL (WR-DLBCL) in the era of rituximab.Methods and Materials:Eighty-three patients with early stage WR-DLBCLwere included in the study. Twenty five patients had stage Ⅰ disease, and 58 patients had stage Ⅱ disease. All patients received rituximab-based chemotherapy with (n = 62) or without (n = 21) radiotherapy.Results:The 5-year overall survival (OS), progression-free survival (PFS) and locoregional control (LRC) rates for the whole group were 89%,84% and 90%. Age, ECOG score, LDH and IPI were significant prognostic factors for OS, while age, bulky disease, ECOG score and IPI were prognostic factors for PFS and LRC. Chemotherapy followed by radiotherapy resulted in a significantly better PFS (94% vs.58%, p = 0.003) and LRC (100% vs.61%, p< 0.001), with a marginal difference of OS (94% vs.71%, p = 0.063) compared with chemotherapy alone.Conclusion:Radiotherapy following rituximab-based chemotherapy significantly improved PFS and LRC, probably OS for early stage WR-DLBCL in the rituximab era.Part 3:Dosimetric and Clinical Outcome with Intensity-modulated Radiation Therapy after Chemotherapy for Patients with Early-stage Diffuse Large B-cell Lymphoma of Waldeyer’s RingPurpose:To assess the dosimetric benefit, prognosis and toxicity of intensity-modulated radiation therapy (IMRT) for early-stage, diffuse large B-cell lymphoma of Waldeyer’s ring (WR-DLBCL).Methods and Materials:Sixty-one patients with early-stage WR-DLBCL received chemotherapy followed by IMRT. Dosimetric parameters for the target volume and critical normal structures were evaluated and survival calculated. Linear regression analysis was used to assess the effect of the mean dose (Dmean) to the parotid glands upon xerostomia.Results:The median conformity index (CI) and homogeneity index (HI) of the planning target volume (PTV) were 0.83 and 0.90, respectively, demonstrating very good coverage of the target volume. Mean dose to the parotid glands was 24.9 Gy. Five-year overall survival (OS), progression-free survival (PFS), and locoregional control (LRC) were 94.7%,93.1%, and 98.3%, respectively. Acute and late toxicities were mild, and no patient developed late toxicities of grade≥3. Dmean to the parotid glands had a linear correlation with late xerostomia of grade≥2.Conclusions:IMRT after chemotherapy can provide excellent dose conformity and achieve favorable survival and LRC with mild toxicities in patients with early-stage WR-DLBCL. Dose constraints of IMRT for the parotid glands should be limited to<24 Gy.