Preliminary results of CyberKnife stereotactic radiotherapy (SBRT) boost for primary head and neck cancers: is it the future direction?

Aim: To analyse the preliminary results of CyberKnife stereotactic radiotherapy (SBRT) boost in primary head and neck cancer patients among Indian population. Methods and materials: A total of nine patients of primary head and neck cancer were treated with CyberKnife SBRT boost after intensity-modulated radiation therapy (IMRT). The median phase 1 IMRT dose was 54 Gy/27 fractions. Histological types included squamous cell carcinoma (n = 7) and adenoid cystic carcinoma (n = 2). Response was evaluated using positron emission tomography/computed tomography and detailed clinical examination. Results: As a preliminary analysis with median follow up of 8 months (range: 6-19 months), phase 2 median tumour volume of 16 center dot 3 cc and a median dose of 5 Gy per fraction, eight patients had loco-regionally stable disease and one had distant metastasis. With objective assessment five patients had complete response. Treatment was well tolerated with no grade 3 or more acute toxicities directly related to CyberKnife boost. Conclusion: CyberKnife SBRT boost is an attractive option for primary head and neck cancers especially where disease is in close proximity to critical structures hindering radical dose delivery. Future prospective analysis and optimum assessment of total biological effective dose (BED) in a properly selected case might actually benefit the use of CyberKnife SBRT boost.