Colorectal cancer incidence in pattern and model makers: evidence from a screening program

Colorectal cancer-associated nuclear antigen

By using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting assays in the presence of polyclonal antiserum raised against electrophoretically specific polypeptides of colorectal cancer nuclear polypeptides with M(r) of 35-40 kDa, we have identified p36 protein whose expression accompanies tumorigenesis of large intestine. Immunological analysis of 35 nuclear protein preparations has indicated expression of p36 antigen in nine of 11 right-sided (81.8%) and 21 of 24 (87.5%) left-sided colorectal tumor cases, but not in any control tissue samples. In this study, we have identified p36 antigen in two colon tumor cell lines, i.e., SW620 and HT29 as well. Fractionation experiments based on selective extraction of nuclei isolated from cancerous specimens, which enables their separation into chromatin, nuclear matrix and its subfraction, i.e., internal and peripheral matrix have revealed the concentration of this particular antigen in the internal matrix.

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 disease process. Numerous epidemiologic studies suggest that rates of occurrence of colorectal adenocarcinoma at particular anatomic subsites (e.g., right colon, left colon, and rectum) may be associated with distinctive geographic, demographic, and risk factor profiles. This study explored time trends over a 22-year period of the incidence of adenocarcinoma of the colon and rectum at various subsites among patients of different race, gender, and stage of disease.

METHODS

Data on the incidence of colorectal adenocarcinoma were obtained from a population-based cancer registry in the Detroit, Michigan area funded by the National Cancer Institute. Age-adjusted incidence rates were analyzed by year of diagnosis. Relative survival rates were also obtained for different race and gender categories, along with disease stage at diagnosis.

RESULTS

A major rise was revealed in the incidence of adenocarcinoma in the right colon among African American men and women between the mid-1970s and the early 1980s. The rise was greatest among African American men and accounts for increases in late stage disease among them. Corresponding decreases in survival among African American men were noted.

CONCLUSIONS

These findings indicated widely differing disease patterns based on anatomic subsite and patient demography and also indicated a need for targeted efforts at early detection of adenocarcinoma of the right colon among African Americans.