Cancer prevalence estimates based on tumour registry data in the Surveillance, Epidemiology, and End Results (SEER) Program

Background The Connecticut Tumor Registry (CTR) has collected cancer data f or a sufficiently long period of time to capture essentially all prevalent cases of cancer, and to provide unbiased estimates of cancer prevalence. Ho wever, prevalence proportions estimated from Connecticut data may not be re presentative of the total US, particularly for racial/ethnic subgroups. The purpose of this study is to apply the modelling approach developed by Capo caccia and De Angelis to cancer data from the Surveillance, Epidemiology, a nd End Results (SEER) Program of the National Cancer Institute to obtain mo re representative US site-specific cancer prevalence proportion estimates f or white and black patients. Methods Incidence and relative survival were modelled and used to obtain es timated completeness indices of SEER prevalence proportions for ail cancer sites combined, stomach, cervix uteri, skin melanomas, non-Hodgkin's lympho mas, lung and bronchus, colon/rectum, female breast, and prostate. For vali dation purposes, modelled completeness indices were computed for Connecticu t and compared with empirical completeness indices (the ratio of Connecticu t based prevalence proportion estimates using 1973-1993 data to 1940-1993 d ata). The SEER-based modelled completeness indices were used to adjust SEER prevalence proportion estimates for white and black patients. Results Model validation showed that the adjusted SEER cancer prevalence pr oportions provided reasonably unbiased prevalence proportion estimates in g eneral, although more complex modelling of the completeness indices is nece ssary for female cancers of the colon, melanoma, breast, cervix, and all ca ncers combined. The SEER-based cancer prevalence proportions are incomplete for most cancer sites, more so for women, whites, and at older ages. For a ll cancers combined, prevalence proportions tended to he higher for whites than blacks. For the site-specific cancers this was true for stomach, prost ate, cervix uteri, and lung and bronchus (men only). For colon/rectal cance rs the prevalence proportions were higher for blacks through ages 59 (men) and 64 (women), and then for the remaining ages they were higher for whites . Prevalence proportions were lowest for stomach cancer and highest for pro state and female breast cancers. Men experienced higher prevalence proporti ons than women for skin melanomas, non-Hodgkin's lymphomas, lung and bronch us, and colon/rectal cancers. Conclusion The modelling approach applied to SEER data generally provided r easonable estimates of cancer prevalence. These estimates are useful becaus e they are more representative of cancer prevalence than previously obtaine d and reported in the US.