Colorectal cancer trends by race and anatomic subsites, 1975 to 1991
K. C. Chu, R. E. Tarone, W. H. Chow and G. A. Alexander
Special Populations Studies Branch, National Cancer Institute, Bethesda, Md., USA.
OBJECTIVES: 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. DATA SOURCES:
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.
MAIN OUTCOME MEASURES: Trends in incidence, survival, and mortality rates.
RESULTS: 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. CONCLUSIONS: 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.
