The importance of long-term follow-up of head and neck cancer patients for reliable survival analysis.

Abstract

Analyze the influence of patients lost to follow-up in estimated survival rates calculated by the Kaplan-Meier method. Only patients with previously untreated squamous cell carcinoma of the upper aerodigestive tract were selected. For the patients lost to follow-up anytime, the last medical evaluation date was collected to calculate the "estimate A" survival time. If the same patient returned to our outpatient clinic or further health information was obtained, the updated last information/evaluation date was also collected to calculate "estimate B" survival time. The survival curves considering "estimate A" and "B" survival rates were compared. The overall 5 and 10-years survival rates for all patients calculated for "estimate A" were 54.0% and 46.0%, respectively; compared with 42.8% and 28.2% when were calculated considering "estimate B" (P < 0.001). Close follow-up of the head and neck cancer patients is essential for an accurate estimate of survival by Kaplan-Meier method.