Breast Cancer: Racial Disparities

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Breast Cancer: Racial Disparities


Guest: Dr. Joan Cunningham - Bioinformatics & Epidemiology

Host: Dr. Linda Austin – Psychiatry

Dr. Linda Austin: I am Dr. Linda Austin. I am talking today with Dr. Joan Cunningham who is research assistant professor in the department of Biostatistics, Bioinformatics and Epidemiology. Dr. Cunningham is an epidemiologist with a special interest in breast cancer and, particularly, racial disparities in breast cancer. Dr. Cunningham, can you characterize, in a nutshell, what are the racial disparities in breast cancer, especially here in South Carolina?

Dr. Joan Cunningham. Sure. Throughout the United States, black women are less likely to get breast cancer, but they are also more likely to die from it. So, the risk is higher for white women getting the disease, but the risk of dying from it is higher in black women.

Dr. Linda Austin: Now, how much higher is the risk of getting breast cancer in white women versus black women?

Dr. Joan Cunningham: In white women, the risk of developing breast cancer is about 10 to 13 percent. But, the risk of dying from it is about 40 to 45 percent higher in black women.

Dr. Linda Austin: And, obviously, the thrust of your research is to look at why that might be. What are some of the factors involved in that disparity?

Dr. Linda Cunningham: Well, you know, if we knew all the answers, I would not need to have a job anymore. It is a complicated picture. Basically, white women are at a greater risk of having breast cancer at an older age. So, with many cancers, the risk of developing the cancer increases as we get older. With breast cancer, it really keeps increasing as we get older. That is especially true for white women, and less true for black women. So, that is part of the disparity. That is that older women are at a greater risk if they are white women. So, why should that be? That is really about a million and a half dollar question. There are a number of theories that pertain to reproductive history, whether you have had children or not, whether you have nursed your children, if you have used hormone replacement therapy and so on.

There are probably lifestyle factors that we do not understand really well that must contribute to some of these disparities. But, I suspect there are also some genetic differences and a number of people are trying to research that area. Now, when I say that white women, older white women, have a higher chance of getting breast cancer, there is a little bit of a flip side to that. That is that, in the younger ages, let’s say 30s, 40s, black women actually have a higher incidence of developing the cancer, than do white women. The type of cancer that black women are more likely to get is a more aggressive form and that is true, really, at any age. So, even though black women are less likely to develop breast caner, they are more likely to have a more aggressive form of it. The reasons for that, you know we can keep going back and back, further and further, with the why question, but the reasons for that, again, are not really clear.

A number of people think there probably are some genetic predispositions involved. We do not know what they are, yet. In terms of survival itself, there is a lot of literature that indicates that, whether it is breast cancer or some other type of cancer, black patients may not have the same treatment as white patients do. So, there are many different factors that go into this higher mortality. One of them is the more aggressive disease, but another is, for whatever reason, perhaps, less state-of-the-art treatment.

Dr. Linda Austin: My understanding is that the earlier breast cancer develops, the more aggressive the course of the illness tends to be. Am I correct in that belief?

Dr. Joan Cunningham: That is generally true. Of course, there are a lot of exceptions. But, that is generally true. A cancer that tends to be more aggressive with an earlier onset also suggests there is a genetic reason somewhere in the cause of that cancer. So, yes, you are basically correct, that it tends to be a more aggressive form of disease.

Dr. Linda Austin: But, when you compare it, let’s imagine a 40-year-old black woman with a 40-year-old white woman, both of whom have just gotten the diagnosis, who are at the same stage and have the same type of cancer.

Dr. Joan Cunningham: Ahh, who have the same type of cancer?

Dr. Linda Austin: Yes, same stage and same type. I mean, is it an issue, for example, of getting a diagnosis at a different stage or is it an issue of being more likely to have a different type of breast cancer?

Dr. Joan Cunningham: Yes, and yes. So, it is a very complicated picture. The diagnosis at a later stage, yes, black women are more likely to have a diagnosis at a later stage. But, that may not be simply a matter of less access to early diagnosis. These more aggressive cancers tend to also grow more rapidly and to spread more rapidly. So, even a smaller cancer in a black woman may be at a later stage because it has spread to the lymph nodes already. I do not want to alarm all the black women listening out there. I mean, these are just the statistics. The white women, really, are the ones who are at the greater risk of developing a breast cancer, except in those earlier years of, say, 30s, early 40s.

Dr. Linda Austin: What direction is your research taking in trying to unravel these issues, these questions?

Dr. Joan Cunningham: Well, I have projects in different areas. I am working with Dr. _____ at the University of South Carolina in Columbia. He is a population geneticist. We are actually working with some DNA samples that have been donated by several hundred breast cancer patients in the Columbia area, to look at some candidate genes and see whether there may be some particular, what we call, polymorphisms or different forms of these genes associated with a more aggressive type of disease. That is one avenue of research. I am also looking at data from national and state registries to try and really pin down the nature of these disparities in a way that is very comparable between states, from state to state. So, I am looking at it in terms of incidence of data. I am also working with Mike Bird and some others at DHEC, to use data from the Best Chance Network, to see if we can try and isolate the effects of socioeconomic status, which tends to be associated with access to early detection, to see if we can isolate the effects of socioeconomic status from whatever the other risk factors are for breast cancer. We are trying to determine how socioeconomic status may, or may not, contribute to the aggressiveness of the cancer that is detected.

Dr. Linda Austin: Have you looked at issues of differences in treatment protocols used?

Dr. Joan Cunningham: I, personally, have not. My understanding is that even if the same treatments are given, black women tend to do more poorly in terms of survival from their breast cancer. I understand, currently, that the mortality rate for black women is still higher and there are quite a number of people, not myself, who are looking into why that might be. I can tell you that reasons generally considered as likely are other health problems that may make it more difficult to tolerate the treatments. Perhaps, not having adequate health insurance, of course, is a big one. I think there a number of possible explanations.

Dr. Linda Austin: What about issues pertaining to weight, hypertension, diabetes? Do those sorts of issues play a role in nutritional status, for example?

Dr. Joan Cunningham: In terms of survival?

Dr. Linda Austin: In terms of racial disparities.

Dr. Joan Cunningham: Well, there certainly are differences between black and white women in terms of body mass index, rates of diabetes, hypertension. Black women, on the whole, tend to have more of these other health problems than white women. So, there are certainly differences there, between racial groups. Now, as to the causes of that, it is complicated.

Dr. Linda Austin: Dr. Cunningham, thank you so much for talking with us today.

Dr. Joan Cunningham: You are welcome. I have enjoyed it.

If you have any questions about the services or programs offered at the Medical University of South Carolina or if you would like to schedule an appointment with one of our physicians, please call MUSC Health Connection: (843) 792-1414.

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