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.
Lee
A W
AW
Radiotherapy and Oncology Department, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong.
Chan
D K
DK
Fowler
J F
JF
Poon
Y F
YF
Law
S C
SC
Foo
W
W
O
S K
SK
Tung
S Y
SY
Cheung
F K
FK
Ho
J H
JH
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