Hypofractionated stereotactic radiotherapy using CyberKnife as a boost treatment for head and neck cancer, a multi-institutional survey: impact of planning target volume

Anticancer Res. 2014 Oct;34(10):5755-9.

Abstract

Aim: To evaluate the role of hypofractionated stereotactic radiotherapy (hSRT) as a boost treatment for head and neck cancer.

Patients and methods: We conducted a multi-institutional retrospective review for the outcome of boost irradiation using CyberKnife for head and neck cancer patients from the charts of four Institutes. Twenty-five patients were treated with hSRT boost for primary site with a median follow-up of 28 months. Treatment sites were 11 nasopharynx, 7 oropharynx, one hypopharynx, 3 nasal cavity or paranasal sinus and three oral cancers. All patients underwent preceding conventional radiotherapy of 35 to 72 Gy (median, 50 Gy) in 1.2- to 2 Gy-fractions. The dose and fractionation scheme of the Cyberknife SRT boost was individualized and the prescribed dose ranged from 12 Gy to 35 Gy in 1 to 5 fractions (median, 15 Gy in 3 fractions).

Results: There were 18 complete responses, 6 partial responses and one progressive disease, resulting in 96% (24/25) response rate. Local control (LC) rates at 2- and 5-years were 89% and 71%, respectively. Progression-free survival (PFS) and overall survival (OS) at 2- and 5-years were 70%/ 83% and 70%/ 70%, respectively. Planning target volume (PTV) at boost treatment planning and initial response were predisposing factors for PFS and OS. Patients with PTV ≤ 20 cm(3) showed better PFS (92%) and OS (100%) than those with a PTV > 20 cm(3) (PFS, 61% and OS, 47%). Good initial response predicts better outcome in LC, PFS and OS.

Conclusion: The results of the present study showed potential benefits of the CyberKnife hSRT boost. Smaller PTV and good initial response predict good outcome.

Keywords: CyberKnife; Head and neck cancer; boost therapy; stereotactic radiotherapy.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Dose Fractionation, Radiation
  • Female
  • Follow-Up Studies
  • Head and Neck Neoplasms / drug therapy
  • Head and Neck Neoplasms / mortality
  • Head and Neck Neoplasms / pathology
  • Head and Neck Neoplasms / surgery*
  • Humans
  • Male
  • Middle Aged
  • Neoplasm Staging
  • Prognosis
  • Radiosurgery*
  • Radiotherapy Planning, Computer-Assisted
  • Treatment Outcome
  • Young Adult