Locoregional control after intensity-modulated radiotherapy for nasopharyngeal carcinoma with an anatomy-based target definition.
OBJECTIVE
The objective of the study was to evaluate locoregional control after intensity-modulated radiotherapy for nasopharyngeal cancer using a target definition along with anatomical boundaries.


METHODS
Forty patients with biopsy-proven squamous cell or non-keratinizing carcinoma of the nasopharynx who underwent intensity-modulated radiotherapy between April 2006 and November 2009 were reviewed. There were 10 females and 30 males with a median age of 48 years (range, 17-74 years). More than half of the patients had T3/4 (n = 21) and/or N2/3 (n = 24) disease. Intensity-modulated radiotherapy was administered as 70 Gy/33 fractions with or without concomitant chemotherapy. The clinical target volume was contoured along with muscular fascia or periosteum, and the prescribed radiotherapy dose was determined for each anatomical compartment and lymph node level in the head and neck.


RESULTS
One local recurrence was observed at Meckel's cave on the periphery of the high-risk clinical target volume receiving a total dose of <63 Gy. Otherwise, six locoregional failures were observed within irradiated volume receiving 70 Gy. Local and nodal control rates at 3 years were 91 and 89%, respectively. Adverse events were acceptable, and 25 (81%) of 31 patients who were alive without recurrence at 2 years had xerostomia of ≤Grade 1. The overall survival rate at 3 years was 87%.


CONCLUSIONS
Target definition along with anatomically defined boundaries was feasible without compromise of the therapeutic ratio. It is worth testing this method further to minimize the unnecessary irradiated volume and to standardize the target definition in intensity-modulated radiotherapy for nasopharyngeal cancer.
*6-5-1, Kashiwanoha, Kashiwa, Chiba, Japan 277-8577. mkawashi@east.ncc.go.jp.
Mitsuhiko
M
Kawashima
Takaki
T
Ariji
Satoru
S
Kameoka
Takashi
T
Ueda
Ryosuke
R
Kohno
Teiji
T
Nishio
Satoko
S
Arahira
Atsushi
A
Motegi
Sadamoto
S
Zenda
Tetsuo
T
Akimoto
Makoto
M
Tahara
Ryuichi
R
Hayashi
D000293:Adolescent; D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000532:radiotherapy*; D018572:Disease-Free Survival; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D009364:Neoplasm Recurrence, Local / Q000517:prevention & control / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted; D011881:Radiotherapy, Computer-Assisted / Q000009:adverse effects; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects
anatomical compartment; intensity-modulated radiotherapy; nasopharyngeal cancer; patterns of spread