Colorectal cancer trends by race and anatomic subsites, 1975 to 1991

To determine whether colorectal cancer rates among black men and women show the abrupt declines seen in whites since the mid-1980s and to determine how the cancer trends vary by anatomic subsites.

Mortality data from the National Center for Health Statistics, Hyattsville, Md, and incidence and survival data from the Surveillance, Epidemiology, and End Results program of the National Cancer Institute, Bethesda, Md.

Trends in incidence, survival, and mortality rates.

For white men and women, cancer incidence rates declined for the right colon, left colon, and rectum after 1985. Stage-specific incidence rates for white men and women for each subsite had generally similar patterns. Distant-disease incidence rates declined beginning in the late 1970s, whereas regional-disease rates increased until the early to mid-1980s and then declined. An exception is the right colon in men, for which the incidence rates of distant disease did not decline, although the regional-disease pattern was similar to other sites. For blacks, colorectal cancer incidence rates changed little in the 1980s for men or women. In particular, there were no significant declines in the cancer incidence rates of the colorectum or of subsites after 1985. Black colorectal cancer mortality trends showed gender and age differences. Black men had significantly increasing colorectal cancer mortality rates from 1975 through 1992, but the increase after 1985 was observed only in men 65 years of age and older. The colorectal cancer mortality rates did not increase overall in black women in the 1980s, but the mortality rates increased slightly in women 65 years of age and older while declining in women younger than 65 years.

For whites, the trends in colorectal cancer rates by anatomic subsite support the contention that early-detection procedures, such as sigmoidoscopy and colonoscopy, are contributing to the declines in incidence and mortality rates since 1985. The absence in blacks of significant declines in colorectal incidence or mortality rates since 1985 suggests the need for a greater emphasis on early-detection programs in the black community, particularly for elderly blacks.