Black-white differences in stage-specific cancer survival: analysis of seven selected sites

A number of researchers have noted that the black population in the United States generally has less favorable cancer survival than does the white population. It is not clear, however, whether this difference is fully explained by differences in stage of disease at diagnosis. This study uses Surveillance, Epidemiology, and End Results program data from the San Francisco-Oakland (California) Metropolitan Statistical Area for the years 1974-1985 to study survival differences between blacks and whites while controlling for both stage and age at diagnosis. The cancer sites examined are those for which mortality is considered avoidable by early detection and treatment, namely the colon, rectum, bladder, breast, cervix, uterine corpus, and prostate. Stage-specific (local, regional, and remote) survival curves are examined for each cancer site. The site- and stage-specific curves for colon, male rectal, and prostate cancer, supplemented by proportional hazards analyses, indicate no significant stage-specific racial differentials. Stage-specific survival differentials persist for male bladder, female rectal, and breast cancer. The relation between race and stage is more complex for female bladder, cervical, and uterine corpus cancer; for these sites, there is a racial difference at some stages but not all. The consequences for secondary intervention programs are considered for the seven sites in light of these findings.