PROSTATE and breast cancer are more deadly for African Americans than for whites. Now it seems that differences in the activity of key genes may be partly to blame.
Black men in the US are around than their white counterparts, and twice as likely to die from the disease.
Until now, socioeconomic factors such as access to healthcare have mainly been blamed. But at the annual meeting of the in San Diego, California, on 15 April, Tiffany Wallace of the US National Cancer Institute in Bethesda, Maryland, implicated biological differences between the tumours of blacks and whites.
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When Wallace and her colleagues screened prostate tumours removed from 33 African American and 36 white patients, they found 160 genes differing in activity between blacks and whites, many tied to immunity.
The differences could mean that tumours are more inflamed in black people. But some genes identified govern production of interferons, which defend against viruses. So it鈥檚 possible the extra cases of prostate cancer in African Americans could be due to a higher rate of infection with an unknown cancer-causing virus. The team is now trying to find out if this is the case.
African American women, meanwhile, are slightly less likely to develop breast cancer than whites 鈥� but it often strikes them younger and is more lethal. Lori Field of the Windber Research Institute in Pennsylvania compared breast tumours taken from 26 pairs of black and white women, matched for age and the stage of their cancer, who were either members of the US military, or were the dependantof a serving member. All of the patients were being treated at the Walter Reed Army Medical Center in Washington DC, minimising biases due to racial disparities in access to healthcare.
The researchers found 65 genes with significantly different levels of activity between tumours from the black and white patients. This time, there was no clear link with the immune system.
Few of the genes identified had previously been linked to cancer, so what caused the differences is unclear. Field suggests that mutations in some genes may be involved, or altered 鈥渆pigenetic鈥� chemical regulation of genes. 鈥淲e really don鈥檛 know at this time.鈥� The long-term goal, she says, is to identify new targets for drugs 鈥� which could improve survival prospects for African Americans.
Cancer 鈥� Learn more about one of the world鈥檚 biggest killers in our comprehensive special report.
Genetics 鈥� Keep up with the pace in our continually updated special report.
