T-1 NASOPHARYNGEAL CARCINOMA - THE EFFECT OF WAITING TIME ON TUMOR-CONTROL

Purpose: To study the effect of unperturbed tumor growth on the contro l of nasopharyngeal carcinoma. Methods and Materials: This is a retros pective analysis of 290 patients with T(1)N(0-3)M(0) disease (Ho's cla ssification) treated by the same technique and dose schedule to the na sopharyngeal region. The median interval from diagnosis to commencemen t of irradiation was 26 days (range: 8-68 days). Cox proportional haza rds analyses were performed to study the independent effect of waiting time on the probability of failure at various sites. Actuarial failur e-free survival of patients with delay < 22 days, 22-28 days and > 28 days were also compared to illustrate the clinical observation. Result s: Both tests showed that waiting time had no significant impact on lo cal failure: The N-stage stratified hazard ratio was 0.985 per day, an d 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-s tage stratified hazard ratio for distant failure was 1.020 per day, an d the corresponding metastasis-free survival in patients with N-2-3 di sease 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 3 3%, respectively. Conclusion: 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 we re clinically too serious to be ignored.