Study: Prostate Cancer More Likely to Strike Black Men

Ed Gordon talks with Dr. Matthew Freedman, an instructor at Harvard Medical School and associate member of the Broad Institute. He's the author of a new study that suggests African-American men are genetically predisposed to an aggressive form of prostate cancer.

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ED GORDON, host:

From NPR News, this is NEWS & NOTES. I'm Ed Gordon.

The human genome is hugely complex, with millions of genetic markers. But the genes of someone with African ancestry won't look much different from someone of European or Asian descent. Of course, there's an exception to every rule, and this week scientists discovered not one but two. Researchers at Virginia Commonwealth University found a gene that predisposes African-American women to give birth prematurely. And doctors at Boston's Dana Farber Cancer Institute have pinpointed a genetic region that predisposes African-American men to aggressive prostate cancer. For more on the cancer study that appeared in this week's proceedings of the National Academy of Sciences, I spoke with the study's lead author, Dr. Matthew Freedman. He says their findings could someday save a lot of lives.

Dr. MATTHEW FREEDMAN (Instructor, Harvard Medical School): Once you start to understand which genes are influencing the development of the disease you can then entertain the notion of developing therapies around that particular gene or genetic variant or pathway.

The second thing has to do with screening and diagnosis. So it does appear that men that do inherit this particular region of DNA are at a higher risk. And perhaps we can start entertaining the notion of screening men for this particular DNA variant so that either prevention efforts or more intensive screening - maybe with PSA or biopsies - may be done at an earlier stage.

GORDON: Doctor, what was it that allowed you to uncover what some might say had been there all the time or did we see a morphing of this gene down the line?

Dr. FREEDMAN: That's a very interesting question. There is a distinction here. We have found a region. We've identified a region of DNA that's still 3,800,000 bases long, so it's still a considerable distance. But we've essentially gone from looking at 100 percent of DNA to one percent of DNA. And we are in the genetic neighborhood, so to speak. But we still need to find the actual address and the actual DNA change responsible for disease. That we haven't found. But we are pursuing that aggressively right now.

GORDON: Are typically, these used as stepladders and do we see elevated learning at that point, once something has broken, as we've seen this?

Dr. FREEDMAN: I think so. Prior to this finding - and I just want to mention that there's another group, as well, that has discovered - we've converged on the same region - and that's the deCODE Group in Iceland that was reported back in May. And so it really looks like this is a bona fide risk locus. And it really, in my mind, is the first time where we're seeing a genetic risk factor that has been tied to prostate cancer risk that affects a substantial portion of the population. Prior to this the only generally accepted risk factors were age, family history, and ethnicity.

GORDON: And that's where I was going to go in terms of the geographical suggestion of all of this, and why certain diseases affect a particular race and then often a particular race from a particular region. When we look to try to illustrate that and find out why that is the case, how much have we learned of this?

Dr. FREEDMAN: We're still in the early days of really deciphering disease as we know it. So we don't know what sort of sets off a particular pattern of developing a disease. And these are tools that are helping us to try and understand this. There are different disease rates, as you mentioned, for different ethnic groups and this may be due to genetic factors in some cases. It may be due to environmental or behavioral factors in some cases. And this is exactly what scientists are currently trying to tease apart.

GORDON: How much does this help in assisting monies to come in, development to grow, people to look at the importance of being able to eradicate the ills that we often find?

Dr. FREEDMAN: This is a very good and timely question, especially given that funding from the National Institutes of Health has actually decreased for biomedical research, of late. And from where I sit, this is one mechanism and one way in which we can understand disease pathogenesis, really, for the first time in human history - at least the genetic contribution. And that has really been a breakthrough and is a direct result of the sequencing of the human genome project. And just in the past year, a very rich catalog of human variation - how we, as a human species, actually vary at the DNA level. And that's publicly available information and I think it really is starting to transform science. And there are a lot of people very excited about this. But again, I think time will tell what medical impact this will end up having. This particular finding that we've described in our paper is actually a substantial population impact. In other words, this appears to be responsible for 50 percent of prostate cancer cases in younger African-American men.

GORDON: Let me ask you this as a closing question, because we'll get into this in just a moment with our other guest, but I'm curious, how much of this really speaks to the issue of race as a social construct? That's one of those age-old arguments as to whether or not we're all the same or whether there are variances with race, region, et cetera.

Dr. FREEDMAN: Yes. This is, again, a very timely topic. And I think now the answer is really emerging pretty clearly, since we do have this comprehensive catalog of variation. And what has become very, very clear, is that as a human race, we are all much more similar to each other than we are different. In other words, a particular variant that you see in one population, it is very likely that you will see that variant again in another ethnic population. There is more variation within a particular ethnic population than there is between.

GORDON: Well doctor, good luck as you continue to read into all of this and see the study, and we greatly appreciate your time today.

Dr. FREEDMAN: Oh, it was my pleasure. Thank you for having me.

GORDON: That was Dr. Matthew Freedman, an instructor at Harvard Medical School and associate member of the Broad Institute. He joined us from member station WBUR in Boston.

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