Researchers have discovered that a genetic mutation known to affect resistance to chemotherapy occurs more frequently in some ethnic groups than in others. According to study results presented on Sunday in New Orleans at the annual meeting of the American Association for Cancer Research, African and African-American populations contain a higher number of individuals carrying the drug-resistant gene than do Caucasian and Asian populations. The findings could help explain why some patients of African descent respond poorly to anti-cancer drugs.

Although the mutations we hear about are usually associated with hazardous results, some can confer benefits. Howard L. McLeod of Washington University and his colleagues studied a genetic mutation that, in effect, allows chemotherapeutic drugs to do their jobthat is, enter tumor cells and kill them. In its normal state, the gene produces a protein known as PGP that rids cells of drugs. Analyses of DNA test results from 1,280 participants from 10 ethnic populations revealed that Ghanaian, Kenyan, Sudanese and African-American populations have a lower incidence of the helpful mutation.

The study could point the way to more individualized therapy for people who overexpress the PGP protein, perhaps incorporating an existing medication that inhibits it. "While I believe that the biggest reason some African-American cancer patients do not do as well as Caucasian patients is because of their access to care, this finding suggests that there is a little bit more to it," McLeod notes. "Knowing this, we should be able to help decrease the variability in the way people are treated."