Nasopharyngeal carcinoma: repeat treatment with conformal proton therapy--dose-volume histogram analysis.
OBJECTIVE
To analyze control, survival, and complication rates of conformal proton radiation for recurrent nasopharyngeal carcinoma.


METHODS
Sixteen patients with nasopharyngeal carcinoma initially treated with 50.0-88.2 Gy photons were re-treated with protons to additional doses of 59.4-70.2 CGE. Local-regional control and survival were correlated with extent of relapse, recurrence versus persistence, and prescribed dose and were subjected to dose-volume histogram analysis. Mean follow-up was 23.7 months (range, 4-47 months).


RESULTS
Twenty-four-month actuarial overall and local-regional progression-free survival rates were both 50%. The 24-month actuarial overall survival rates for patients with "optimal" dose-volume histogram coverage versus "suboptimal" coverage were 83% and 17%, respectively (P = .006). Doses to critical structures were low (0-22.0 Gy); no central nervous system side effects supervened.


CONCLUSIONS
Adequate tumor coverage, as evaluated by using dose-volume histogram analysis, was found to be the most important variable influencing local-regional control and survival. No central nervous system complications were observed; increases in the dose to adjacent critical structures are being evaluated.
Lin
R
R
Department of Radiation Medicine, Loma Linda University Medical Center, CA 92354, USA.
Slater
J D
JD
Yonemoto
L T
LT
Grove
R I
RI
Teichman
S L
SL
Watt
D K
DK
Slater
J M
JM
D000328:Adult; D000368:Aged; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000401:mortality / Q000532:radiotherapy*; D009364:Neoplasm Recurrence, Local / Q000401:mortality / Q000532:radiotherapy*; D011379:Prognosis; D015996:Survival Rate