Abstract

Volumetric Modulated Arc Therapy (VMAT) is a radiotherapy in head and neck cancer can be delivered by two boost techniques: Sequential Boost (SEQ) and Simultaneous Integrated Boost (SIB). There is still limited data comparing these two techniques.
Aim: To compare SEQ and SIB planning techniques of VMAT in patients of Head And Neck Squamous Cell Carcinoma (HNSCC) in terms of disease response and acute toxicities.
Materials and Methods: A prospective interventional study was conducted at Geetanjali Medical College and Hospital, Udaipur, Rajasthan, India from January 2019 to December 2020. Fifty two patients of HNSCC planned for radical chemoradiation were enrolled into two study arms SEQ-VMAT and SIB-VMAT. Chemotherapy given as weekly cisplatin 40 mg/m2. Dosimetric comparison was done using Dose Volume Histogram (DVH) analysis. Response evaluation was done as per Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 at 8-10 weeks follow-up. Acute toxicity evaluation was done as per Radiation Therapy Oncology Group (RTOG) toxicity grading. Statistical analysis was done using Statistical Package for Social Sciences (SPSS) version 20.0 software.
Results: A total of 52 subjects were included in the study, out of which 26 subjects were included in SEB group while 26 subjects in SIB group. No significant difference was observed in demographic data in terms of age 56.2 vs 53.5 years, sex (24 males and 2 females in both the arms), disease site (oropharynx is the most common site 38.5% in both arms)and stage (IVA 69.2% in SEQ arm vs 46.2% in SIB arm and III 30.8% in SEQ arm vs 42.3% in SIB arm). Dosimetric data was comparable between the two arms. SIB-VMAT shows significantly higher incidence of acute dermatitis (grade1 dermatitis at two weeks 69.2% vs 38.5%, p=0.0279 and grade 2 dermatitis at six weeks 84.6% vs 38.5%, p=0.0007) and acute mucositis (grade 1 mucositis at two weeks 84.6% vs 38.5%, p=0.0007) as compared to SEQ-VMAT. SEQ- VMAT shows significantly higher incidence of dysphagia (grade 1 at four weeks 84.5% vs 50%, p=0.0087). No significant differences were observed in terms of xerostomia and laryngeal toxicity.No significant difference in overall response was observed between SIB vs SEQ (complete response 65.4% vs 53.85% p=0.40).
Conclusion: SEQ appears better in terms of acute toxicities but SIB was more convenient as no re-planning was required. For head and neck radiotherapy SIB and Sequential VMAT are comparable in terms of overall response