Conditional survival in head and neck squamous cell carcinoma - Results from the SEER dataset 1973-1998

BACKGROUND. Survival statistics for patients with head and neck squamous cell carcinomas (HNSCC) are commonly calculated from the time of diagnosis. The less commonly employed conditional survival (CS) analyzes survival for patients who have survived a period of time after diagnosis. Useful prognostic information for cancer survivors is provided by CS analysis. Estimated baseline CS parameters for HNSCC were sought using large-scale cancer registry data. METHODS. HNSCC cases identified from the Surveillance, Epidemiology, and End Results (SEER) Program were accessed to identify those diagnosed between 1973 and 1998. Five-year observed, relative, and cumulative CS calculations were performed, with secondary stratification by site, extent of disease, and age. RESULTS. The overall 5-year observed survival for all sites increased from 47.8% for 76,181 included patients from the time of diagnosis to 64.4% for those 43,985 patients alive at 3 years, and thereafter plateaus. The greatest increase in CS was for oropharyngeal cancers, which more than doubled over the first decade of surveillance (26.5%-60%). Distant disease showed a 10-year increase in CS (17.4%-60.4%), whereas localized disease CS was essentially static, ranging from 66.1% to 68.5%; for those over 65 at diagnosis it ranged from 39.9-52.9%, whereas patients < 65 years at diagnosis ranged from 53.8-73.5%. CONCLUSIONS. Benchmark CS estimates for domestic HNSCC cohorts were developed from the SEER database. CS is a useful tool to assist clinicians in predicting the probability of demise from HNSCC for patients surviving 1 or more year after diagnosis.