Early stage nasopharyngeal carcinoma: radiotherapy dose and time factors in tumor control.
OBJECTIVE
To evaluate radiotherapy dose and length of treatment in the control of early stage nasopharyngeal carcinoma (NPC) treated with a combination of external radiotherapy and brachytherapy,


METHODS
We reviewed the records of 133 patients with early stage nasopharyngeal carcinoma (stage I or II, AJC/UICC staging system) who received definitive radiotherapy in Chang Gung Memorial Hospital from 1979 to 1991. The median follow-up time was 7.1 years with a minimum of 2 years. All patients were treated with megavoltage external radiotherapy to the nasopharynx area (63-72 Gy) followed by high dose rate intracavitary brachytherapy (5-16.5 Gy in one to three fractions, spaced 1-2 weeks apart). The median total dose and time of irradiation was 75 Gy (69.8-81.4 Gy) and 11.6 weeks (7.8-20 weeks) respectively. Survival analysis was used to examine the effect of several variables on prognosis.


RESULTS
The 5-year rates were 86.4% for local control, 84.7% for disease free survival, 88.5% for actuarial survival and 84.2% for overall survival. The treatment group (combination of time and dose of irradiation) was the most important prognostic factor according to Cox's proportional hazard model. Patients receiving radiation at a total dose of < or = 75 Gy completed in < 12 weeks showed the best prognosis.


CONCLUSIONS
Treatment time and total treatment dose are both important factors in treating early stage NPC. Decreasing the total radiation time to < 12 weeks and not exceeding a radiation dose of 75 Gy gave the best results.
Chang
J T
JT
Department of Radiation Oncology, Chang-Gung Memorial Hospital, Taiwan. jtchang@tpts5.seed.net.tw
See
L C
LC
Liao
C T
CT
Chen
L H
LH
Leung
W M
WM
Chen
S W
SW
Chen
W C
WC
D000328:Adult; D000368:Aged; D001918:Brachytherapy; D002277:Carcinoma / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D002294:Carcinoma, Squamous Cell / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D009367:Neoplasm Staging; D011379:Prognosis; D016016:Proportional Hazards Models; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D013997:Time Factors