Objective: The relationship was studied between the timing of assessment of complete response and ultimate cure rate in the chemoradiotherapy of advanced head and neck cancer.
Methods: A retrospective review was conducted regarding tumor responses at 4 weeks, 3 months, and 6 months after concomitant chemoradiotherapy using cisplatin and 5-FU for 70 patients with stage III/IV squamous cell carcinoma of the oropharynx, hypopharynx and supraglottic larynx. Predictive values of tumor responses at these three time points for survival and tumor control at 2 years were tested using the chi-square test.
Results: Twelve (17%) patients achieved complete response (CR) at 4 weeks. Because of late regression or early recurrence, the CR rate changed to 18/70 (26%) and 24/70 (34%) at 3 and 6 months, respectively. CR or not at 6 months was significantly correlated with all survival endpoints (P < 0.001), but not those at 4 weeks and 3 months (P > 0.100). Kaplan-Meier estimate of overall survival at 5 years was 63% (95% CI 43-84%) for 24 CR patients at 6 months.
Conclusion: CR rate at 6 months was a better surrogate endpoint than that at 4 weeks or 3 months in this series of patients.