Long-term outcome and toxicity of hypofractionated stereotactic body radiotherapy as a boost treatment for head and neck cancer: the importance of boost volume assessment.
BACKGROUND
The aim of this study was to report the long-term clinical outcomes of patients who received stereotactic body radiotherapy (SBRT) as a boost treatment for head and neck cancer.


METHODS
Between March 2004 and July 2007, 26 patients with locally advanced, medically inoperable head and neck cancer or gross residual tumors in close proximity to critical structures following head and neck surgery were treated with SBRT as a boost treatment. All patients were initially treated with standard external beam radiotherapy (EBRT). SBRT boost was prescribed to the median 80% isodose line with a median dose of 21 (range 10-25) Gy in 2-5 (median, 5) fractions.


RESULTS
The median follow-up after SBRT was 56 (range 27.6 - 80.2) months. The distribution of treatment sites in 26 patients was as follows: the nasopharynx, including the base of the skull in 10 (38.5%); nasal cavity or paranasal sinus in 8 (30.8%); periorbit in 4 (15.4%); tongue in 3 (11.5%); and oropharyngeal wall in 1 (3.8%). The median EBRT dose before SBRT was 50.4 Gy (range 39.6 - 70.2). The major response rate was 100% with 21 (80.8%) complete responses (CR). Severe (grade ≥ 3) late toxicities developed in 9 (34.6%) patients, and SBRT boost volume was a significant parameter predicting severe late complication.


CONCLUSIONS
The present study demonstrates that a modern SBRT boost is a highly efficient tool for local tumor control. However, we observed a high frequency of serious late complications. More optimized dose fractionation schedule and patient selection are required to achieve excellent local control without significant late morbidities in head and neck boost treatment.
Department of Radiation Oncology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
Dong Soo
DS
Lee
Yeon Sil
YS
Kim
Jae Seok
JS
Cheon
Jin Ho
JH
Song
Seok Hyun
SH
Son
Ji Sun
JS
Jang
Young Nam
YN
Kang
Jing Hyoung
JH
Kang
So Lyoung
SL
Jung
Ie Ryung
IeR
Yoo
Hong Seok
HS
Jang
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019583:Dose Fractionation, Radiation; D005260:Female; D006258:Head and Neck Neoplasms / Q000401:mortality / Q000601:surgery*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D016634:Radiosurgery / Q000009:adverse effects* / Q000379:methods*; D013995:Time; D016896:Treatment Outcome