American Association for Cancer Research

Clinical Trials and Special Patient Populations

A final word about genetic differences


I wanted to share one more thing because it’s very important. Sometimes when we talk about ethnic differences, especially in cancer, you hear things like, “Oh, you have breast cancer in African-Americans and you don’t have it in Africa, so it can’t really be anything to do with genetic differences.”

I grew up in Ghana and I’m doing some work there on breast cancer. We have studied the incidence of breast cancer there from 1974 to 1999. What you find is that the peak incidence is in younger women, in the age range of 40 to 45 years old. Now, let’s come to the U.S., and look at Caucasians. The peak incidence here is in older age groups.

Let’s look at African-Americans and compare them to the African women. Is there a similarity there? Yes. Just as we’ve seen in women from Ghana, the incidence of breast cancer in African-American women is more common in younger women, with a peak in the 40- to 50-year-old age group. These are women in different environments, with different diets, but the epidemiology of the disease is very similar. It makes you think.

One argument that has been used to suggest that ethnic origins do not matter in cancer causation or treatment outcomes is that a number of cancers are common in African-Americans but rare in native Africans. This argument is misleading because cancer has not been well-studied in Africans. The example I outlined here suggests that there may be more similarities than we think.


Click here for a brief biography of Dr. Alex A. Adjei