Biological Differences Found in Prostate Tumors from African-American and European-American Men

The Bottom Line

Analysis of gene expressionpatterns in prostate tumors from African-American and European-American men has revealed differences in the expression of genes related to inflammation, the immune response, and cancer cell metastasis.

The Whole Story

Prostate cancer is the most commonly diagnosed cancer and the second leading cause of cancer death among men older than 40 years of age in the United States. However, the incidence and death rates for this disease vary among different racial/ethnic groups. Most notably, African-American men have a higher risk of developing prostate cancer than any other group of American men. In addition, their death rate is twice that of European-American men.

Investigators at NCI's Center for Cancer Research used gene expression profiling methods to study the expression of thousands of genes in prostate tumor samples from 33 African-American and 36 European-American men. For comparison, gene expression patterns were also analyzed in samples of normal prostate tissue obtained from some of the patients.

Previous studies had identified a number of genes that are expressed differently between prostate tumors and normal prostate tissue and that serve, therefore, as markers of prostate cancer. In the new research, the tumors of African-American men and European-American men showed similar overall expression patterns for these genes. However, the researchers identified differences between African-American and European-American men in the levels of expression (higher versus lower) of numerous other genes. These genes are linked to autoimmune diseases, allergy, inflammatory diseases, and cancer cell metastasis. The researchers additionally defined a two-gene "genetic signature" that allowed them to distinguish between the prostate tumors of African-American and European-American men.

Whether or not the differences in gene expression found in this study explain the differences in disease aggressiveness and response to therapy between African-American men and European-American men will be addressed in future studies. If these findings are confirmed in subsequent studies, they could have implications for the choice of cancer therapy. For example, the relatively higher expression of immune-related genes in tumors from African-American men could cause these men to respond differently to immunotherapies than European-American men.

Publication: Wallace TA, Prueitt RL, Yi M, et al. Tumor immunobiological differences in prostate cancer between African-American and European-American men. Cancer Research 2008:68;927-936.