INCIDENCE OF COLORECTAL ADENOCARCINOMA BY ANATOMIC SUBSITE - AN EPIDEMIOLOGIC-STUDY OF TIME TRENDS AND RACIAL-DIFFERENCES IN THE DETROIT, MICHIGAN AREA

BACKGROUND. Colorectal adenocarcinoma may represent more than one dise ase process. Numerous epidemiologic studies suggest that rates of occu rrence of colorectal adenocarcinoma at particular anatomic subsites (e .g., right colon, left colon, and rectum) may be associated with disti nctive geographic, demographic, and risk factor profiles. This study e xplored time trends over a 22-year period of the incidence of adenocar cinoma of the colon and rectum at various subsites among patients of d ifferent race, gender, and stage of disease. METHODS, Data on the inci dence of colorectal adenocarcinoma were obtained from a population-bas ed cancer registry in the Detroit, Michigan area funded by the Nationa l Cancer Institute. Age-adjusted incidence rates were analyzed by year of diagnosis. Relative survival rates were also obtained for differen t race and gender categories, along with disease stage at diagnosis. R ESULTS, A major rise was revealed in the incidence of adenocarcinoma i n the right colon among African American men and women between the mid -1970s and the early 1980s. The rise was greatest among African Americ an men and accounts for increases in late stage disease among them. Co rresponding decreases in survival among African American men were note d. CONCLUSIONS, These findings indicated widely differing disease patt erns based on anatomic subsite and patient demography and also indicat ed a need for targeted efforts at early detection of adenocarcinoma of the right colon among African Americans. (C) 1997 American Cancer Soc iety.