Does aggressive prostate cancer occur more often in specific population groups? Expert Dr. Isaac Powell from Karmanos Cancer Institute discusses some regions with high prostate cancer incidence outside the U.S., the impact of inflammatory cytokines, and how screening recommendations may change.
So, Dr. Powell, worldwide are there factors that drive aggressive prostate cancer?
Dr. Isaac Powell:
Yes, let me address that. In 2015 it was reported that in Ghana, the incidence of prostate cancer was higher than in the United States. It’s also been found in the Caribbean, Jamaica specifically in Haiti, that the incidence in prostate cancer is greater than among African Americans in this country. So that takes us to the question of what is it about Africa that’s responsible for this aggressive cancer. And so I’ve been looking into that issue and finding that it’s not all Sub-Saharan Africa, it’s the West Africa. It’s consistent with the slave trade and what is it about West Africa and also Central Africa that is causing this. And I also found that in East Africa, the incidences of prostate cancer as well as breast cancer is less than West Africa. So what now we’re talking about the environment. What is it about the environment of West Africa versus East Africa. And the environment is in West Africa considered a rainforest and in East Africa is considered a different environment.
The diseases are different. In West Africa, you have such disease as a malaria and yellow fever, acute inflammatory diseases, West Africa, I mean East Africa, you don’t have that you have other things. So it’s the environment of West Africa, the rainforest specifically that causes those particular diseases. Now the genetics is, in those poor inflammatory cytokines that we’ve discussed that causes prostate cancer and, in fact, other benign diseases to be more progressive, protect against these acute infections. So this is…the immune system is very complex. In some cases it protects, in some cases it drives the cancers. This is what is…therefore, cancer is what is called an autoimmune disease. And so what the protection does, it selects the population in West Africa. The population that’s selected, because people don’t die from malaria because of these high expressions of poor inflammatory cytokines but, they do then die from chronic diseases such as cancer because those same genes drive the cancers.
Now, the worldwide scientific organizations have shown a map of West Africa and Central Africa where malaria is very high. That same map shows that prostate cancer is more aggressive in that same area where malaria causes diseases. So the environment has a significant impact on the genome. The environment specifically impacts what I mentioned earlier, the oxidative stress, which is activated by reactive oxygen species. The reactive oxygen species is what is called an unpaired electron which makes it inactive and want…and therefore interacts with various environmental factors. These environmental factors also will activate through RNA methylation. Those two factors are the part of the genome that interacts with the environment, and those two factors interact with pro-inflammatory cytokines. So there is a triangle there that interacts or interplays during cancer and other diseases, and that’s where the environment impacts on the genome causing more cancers in particular populations.
Now, in terms of European Americans, there’s a difference between the Northern European genome gene pools and Southern European gene pools and prostate cancer. And Northern Europe prostate cancer is more aggressive compared to Southern Europe. So it’s not just among people of color. In fact, the color makes very little difference in whether you have an aggressive cancer, particularly in Sub-Saharan West Africa as well as in European. So I just wanted to make that point. And not many people are talking about this, because this is what is called population genetics. Epigenetic, transgenerational, hereditary genetics, those genes are transferred through populations over generations. So that’s what I’ve been learning more recently and there needs to be more discussion about population genetics. We know about familial hereditary, but this is different. This is population hereditary genetics.
That is so interesting. So do you think over time there will be recommendations for…I think it depends too on funding for it, but for screening in certain areas of the world for prostate cancer or for any type of cancer where they have found this to be the case?
Dr. Isaac Powell:
Absolutely. That’s going to be a little while, but that I think should happen, yes.