ASSESSING CHANGES IN THE IMPACT OF CANCER ON POPULATION SURVIVAL WITHOUT CONSIDERING CAUSE OF DEATH

Background: We have previously argued against the calculation of cance r-specific death rates as philosophically undefined and biased. Deaths attributed to cancer during a particular year occur in patients diagn osed during an unknown distribution of past times, so cancer-specific death rates cannot be used to assess changes in the impact of cancer o n survival of the population at specific periods of diagnosis, Purpose : Our goal was to develop and analyze three measures of the impact of cancer on population survival that do not use the attributed cause of death: 1) the age-adjusted proportion of the population diagnosed with cancer in a particular year and projected to be dead of any cause by a particular age; 2) the same measure corrected for population mortali ty; and 3) the expected years of life lost to a 20-year-old individual because of the possibility of a diagnosis of cancer, Methods: Data on all adults diagnosed with any cancer during the period from January 1 973 through December 1990 were obtained from the Surveillance, Epidemi ology, and End Results (SEER) Program of the National Cancer Institute , The measures were calculated separately for various combined sex and race groups, Three 2-year diagnosis periods spaced 5 years apart were considered: 1975-1976, 1980-1981, and 1985-1986, A statistical model was used to extrapolate survival beyond observation; the same model wa s used for patients diagnosed in the three time periods to minimize th e effect of possible model misspecification on changes, Results: Cance r incidence increased for three of the four sex-race groups; age-adjus ted changes from 1975 through 1976 to 1985 through 1986 were +11.5% fo r white men, +6.9% for white women, +15.1% for black men, and -9.2% fo r black women, Human immunodeficiency virus (HIV)-related cancers were responsible for an increased cancer incidence at early ages in white men in the latest time period studied, There was a decrease in the inc idence of gynecologic cancers at early ages; the decrease was greater among black women (-55.1%) than among white women (-39.3%), Age- and i ncidence-adjusted 5-year survival increased by 17.9% for white men, 2. 3% for white women, and 7.4% for black men and decreased by 14.1% for black women, When the data from 1985 through 1986 were compared with t hose from 1975 through 1976, the expected number of years lost to a 20 -year-old individual because of cancer changed as follows for the vari ous sex-race groups: +1.4% for white men (-4.0% if HIV-related cancers were not included in the calculation), +2.1% for white women, +12.2% for black men, and +8.8% for black women. Conclusions: For white men a nd women, there has been an increase in both the incidence of and surv ival following the diagnosis of cancer; the two effects nearly cancel in our measures. The experience of black men and women has worsened be cause of increasing incidence or decreased survival.