T1 nasopharyngeal carcinoma: the effect of waiting time on tumor control.
OBJECTIVE
To study the effect of unperturbed tumor growth on the control of nasopharyngeal carcinoma.


METHODS
This is a retrospective analysis of 290 patients with T1N0-3M0 disease (Ho's classification) treated by the same technique and dose schedule to the nasopharyngeal region. The median interval from diagnosis to commencement of irradiation was 26 days (range: 8-68 days). Cox proportional hazards analyses were performed to study the independent effect of waiting time on the probability of failure at various sites. Actuarial failure-free survival of patients with delay < 22 days, 22-28 days and > 28 days were also compared to illustrate the clinical observation.


RESULTS
Both tests showed that waiting time had no significant impact on local failure: The N-stage stratified hazard ratio was 0.985 per day, and the 10-year local failure-free survival for the three groups was 76%, 80%, and 82%, respectively. A similar result was obtained for nodal control in patients with our scheduled neck irradiation. Although the p value of all tests failed to reach statistical significance, the N-stage stratified hazard ratio for distant failure was 1.020 per day, and the corresponding metastasis-free survival in patients with N2-3 disease was 70%, 65%, and 52%, respectively. For node-negative patients without elective neck irradiation, the hazard ratio was 1.019 per day, with the corresponding regional failure-free rates at 57%, 62%, and 33%, respectively.


CONCLUSIONS
Delay in initiation of treatment to the primary target (within the range observed) did not affect the control rate at irradiated sites, but there was a trend (though statistically insignificant) towards increase in failures at untreated sites that were clinically too serious to be ignored.
Radiotherapy and Oncology Department, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong.
A W
AW
Lee
D K
DK
Chan
J F
JF
Fowler
Y F
YF
Poon
S C
SC
Law
W
W
Foo
S K
SK
O
S Y
SY
Tung
F K
FK
Cheung
J H
JH
Ho
D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000473:pathology* / Q000532:radiotherapy*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009303:Nasopharyngeal Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D011336:Probability; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D013997:Time Factors; D017211:Treatment Failure