Involved-site radiation therapy by volumetric modulated arc therapy versus 3D- conformal radiotherapy for treatment of stages I and II supra-diaphragmatic Hodgkin’s lymphoma

Abstract

Purpose: Based on the observation that recurrences of Hodgkin's lymphoma (HL) typically occur in sites of initial nodal involvement the need to concise radiotherapy to only involved nodes that was termed as involved nodal radiotherapy (INRT) or of involved site lymph nodes, involved-site radiation therapy (ISRT) is starting to be widely accepted to use in early stage HL. We aimed in our study to compare between volumetric modulated arc therapy (VMAT) and 3D-conformal radiotherapy (3D-CRT) in radiation of early stage supra-diaphragmatic HL. Methods: The clinical and dosimetric data of 34 patients affected with stages I and II supra-diaphragmatic HL, treated between January 2011 and September 2015 with combined modalities therapy in a single institution were analyzed. Patients received 2-8 cycles of combination chemotherapy ABVD (Adriamycin, Bleomycin, Vinblastine & Dacarbazine) on days 1 and 15 repeated every 28 days. The clinical target volume (CTV) was contoured based on the pre-chemotherapy CT and PET-CT scans. Modification of the CTV was done according to post-chemotherapy anatomical changes. The radiation dose given was 30 Gy/15 fractions. Results: After a median follow up period of 30 months, the progression free survival (PFS) and overall survival (OS) in both groups were 100%. Oropharengeal mucositis was the commonest toxicity in both groups. There was no statistically significant deference between the acute radiation toxicities in both groups. The D mean valuefor lung was higher in 3D-CRT than VMAT (12.0 ± 6.1 Gy vs. 9.9 Gy ± 8.6 Gy). For the breasts volume, the V 5Gy was slightly higher for 3D-CRT compared with VMAT at, 7.6% and 6.5% respectively. For the heart, V 5Gy and V 10Gy valueswere higher for the RA than for 3D-CRT accounting for (51.9 ± 28.9%) and (41.0 ± 24.6%) versus (40.0 ± 25.9% and 30.7 ± 22.5%) respectively. Thyroid gland mean dose was lower for VMAT (21.8 ± 7.7 Gy) than for 3D-CRT (26.8 Gy ± 4.1 Gy) but did not reach statistically significant value ( P = 0.06). Conclusion: Involved-site VMAT technique is safe and effective in term of providing excellent local control and survival following ABVD-based chemotherapy.