“…Because of the crude method of categorizing stage of disease, the lack of specificity on treatment modalities in the SEER data, and the inclusion of all cases in the population covered by SEER, the results of the current study may not be directly comparable to results from specialized cancer research centers (Antman et al, 1980;Brenner et al, 1982;Chahinian et al, 1982;DeLaria et al, 1978;Jett and Eagan, 1982;Lederman et al, 1987;Lerner et al, 1983;Markman et al, 1986;Vogelzang et al, 1984;Wanebo et al, 1976;Yap et al, 1978). In addition, lifestyle, ethnicity and possibly treatment may differ from those prevailing in other countries (Butchart et al, 1976;Elmes, 1973;Lemesch et al, 1976). In particular, the SEER data set includes patients who may not have been eligible for treatment because of poor performance status, and includes all sites of disease.…”