Background:
Radiotherapy isan important component of the combined modality treatment of limited stage Hodgkin lymphoma. Using such combination resulted in high cure ratesexceeding 90%. Unfortunately, long-term survivors are at increased risk of critical long-term morbidities including second malignancy,lung, and cardiac toxicities. Radiation induced toxicity is related to dose and field size. The concept of involved node radiotherapy (INRT) is to minimize the irradiated volume to cover only the primarily involved nodes, while maintaining high local control rates.
Objectives:The aim of this study is to analyze to what extent reducing the target volume using INRT compared with involved field radiotherapy IFRT, can minimize doses to adjacent normal tissues.
Patients and methods: 20 patients diagnosed with limited stage HL who received 2-4 cycles of ABVD were planned to receive consolidation radiotherapy. For each patient, two plans were generated: IFRT and INRT. The radiotherapy dose used was 20-30 Gy. Organs at risk OARs including lungs, heart, breasts, and thyroid gland were delineated and different dosimetric parameters of both plans were compared.
Results: compared to IFRT, INRT showed significant reduction in mean doses and dose-volume metrics ofcontoured OARs.Mean dose to the heart (17.47/8.98 Gy), to lung (11.5/7.3 Gy), to breasts (left 3.1/1.8 Gy, and right 3.3/1.6 Gy) and to thyroid (17.5/7.1Gy).
Conclusion: reducing the treatment volume from IFRT to INRT is associated with decrease in radiation exposure of OARs with subsequent reduction in late complications.