Cancer Prevention

M. D. Anderson Cancer Center
Cancer Newsline Audio Podcast Series
Date: November 10, 2008
Duration: 0 / 17:04

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Leonard Zwelling, M.D:

Welcome to Cancer Newsline a weekly podcast series from The University of Texas M. D. Anderson Cancer Center in Houston TX. The aim of Cancer Newsline is to help you up to date with the news on cancer research, and the rapidly changing advances in cancer diagnosis, treatment and prevention. We also hope to provide you with the latest information on reducing your family’s risk of being diagnosed with cancer. My name is Doctor Leonard Zwelling I am a professor of medicine and pharmacology here at M. D. Anderson.

Today we will be talking with Dr. Ernest Hawk the M. D. Anderson vice president and division head for Cancer Prevention and Population Sciences and also joining us is Dr. Melissa Bondy professor of Epidemiology and principle investigator of the Mexican-American cohort study which well be discussing in a little bit. Today were discussing the reality of cancer prevention an increasingly feasible affective approach to long term health. Dr. Hawk will explain how is envisions cancer one day being addressed in much the same heart disease is today by treating it’s underline causes prior to the onset of disease. This vision has brought us closer within reach thanks to recent gift to Dr. Hawk’s division in the amount of 35 million dollars. A portion of this extraordinary gift has been allocated to Dr. Bondy’s ground breaking Mexican-American cohort study. With almost 15,000 participants and counting Dr. Bondy tracks the lifestyles and health of Mexican-American families living in the Texas Gulf Coast region in hopes of helping generations of individuals of Mexican-American decent. Thank you both for being here.

Dr. Hawk lets start with you, I think the first thing we want to know about is why cancer prevention is something new? Why is it being used as a strategy to eliminate the risk of cancer?

Ernest T. Hawk, M.D., M.P.H.:

Cancer prevention isn’t necessarily new. Ah… we had effective strategies for a long time for example when women been going for pap smears which reduces the chances of cervical cancer for decades. But progressively where understanding how cancer develops and that leads towards opportunities for prevention.

Zwelling:

Does that create different risk groups that has different prevention strategies used for them?

Hawk:

Yes, absolutely. For example, the general public has a lifetime risk perhaps two anywhere from two to five percent of developing cancer in their life time. The majority of ah…burden of the disease in the population remains cardiovascular disease, but as we are developing effective, preventive and therapeutic strategies in against cardiovascular disease. The prevalence of cancer and the population is increasing, that is allowing us then to understand individual risk to stratify populations currently on the basis of family history personal history of having pre-cancer legions those sort of factors come into play but progressively where able to begin to identify individuals risk and stratify individuals so we can help mitigate that risk.

Zwelling:

What about lifestyle and diet and habits as putting people in different risk categories?

Hawk:

Well of course the biggest risk factor is tobacco use contributes to more deaths in the country than any other lifestyle choice that people make. But we think there are other ways individuals eats, the way they exercise that has to do with cancer risk as well and um…and many of those interestingly track as increase individual risk as they do for other diseases like cardiovascular disease.

Zwelling:

One of the ways we find out about how we might do new prevention and screening strategies is by doing what we call observational study Dr. Bondy can you tell us what a observation study is, how you do it and how that enlist answers to questions?

Melissa L. Bondy, Ph.D.:

Sure, there is several types of studies one can do that would be coined or termed observational studies they are types of studies call case control studies where we have cases that has the disease of interest and we compare them with controls who don’t have that particular disease. We also have studies that we call cohort studies and I’ll talk a little bit about an example of a cohort study that we are doing in our own institution, it’s an Mexican-American study but a cohort study is a group, a population it’s usually a little population. Um…we have designed and developed a population base study of Mexicans in the Houston metropolitan area and where recruiting people based on where they live so we can identify census tracks that have at least 75% Mexican-Americans reside in those census tracks and we recruited them through different means of recruitment and that’s the difficult part is trying to bring people into a study and make sure that they are interested in staying in this type of a study for a long period of time. We recruit them through randomly we started through a type of telethon strategy call random digit dial, we also go door to door and we knock on people doors to see if they would be interested in participating and a study where we understand or begin to understand risk factors that put them at risk for certain disease.

Zwelling:

Let me understand when you talk about a census track your talking about a geographical area. In Houston somewhere, then you go through that geographical area, identify people of the proper ethnic background. Is that what your looking for?

Bondy:

Yes.

Zwelling:

And the comparison group is?

Bondy:

Well because we have people that have certain diseases or certain other factors we have a group of people that are diseased and non-diseased. That develop a disease later that me may be interested to try and understand risk factors that are associated or looking at things important in the development of that disease.

Zwelling:

So in a cohort study you’re looking forward. You identify a large group of people of the specific background who look forward to the development of various diseases and try to associate the development of those diseases with specific characterization of those individuals.

Bondy:

Exactly!

Zwelling:

Person by person.

Bondy:

So we knock on people doors just to see id they fit the criteria of being of Mexican descent first. And then we find out if they will be interested to participate. We also go to a lot of community events and talk about the study if people are willing to participate. If they live within the zip codes, then were able to recruit them but we're moving forward to um… to identify people from all over the county that will be interested in participating that are of Mexican descent.

Zwelling:

What do you think are the biggest objectives of this kind of study? Are and how will the result of the study change the way we practice medicine?

Bondy:

I think the important part of this study is, first of all, that Mexican-Americans are understudied in a growing large population in the United States. They have different types of risk factors, for example, their cancer rates are much lower now. Except their risk factors as we see it in terms of obesity, some of their lifestyle factors are putting them at risk for developing other cancers that they may have been lower risk of developing. Let me give you an example. They have higher rates of cervical cancer because of HPV infection.

Zwelling:

HPV? Human Papilloma Virus.

Bondy:

Um... hmm.

Zwelling:

Go ahead...

Bondy:

However, their rates of breast cancer are slightly lower but what we are seeing is that they developing cancer at a much younger age which we are not sure, we understand why maybe it’s hormonal factors, maybe it’s something they are exposed to in the environment that’s causing them to develop their cancer probably a decade earlier then Caucasian Americans. There rate are similar to African Americans but we still don’t understand why they are developing there cancer at different ages and there much more advanced in diagnosis so it’s really a concern to us to begin to understand that.

Zwelling:

Does this now lead to another kind of study, which we usually call clinical trials, and either of you can answer this question?

Hawk:

Yes, absolutely um…one of the most effective ways of developing a strategy for a clinical trials based on observational data such as that coming out of the Mexican-American cohort study.

Zwelling:

Tell us about the clinical trials you have planned, or you're in the middle of?

Hawk:

Well of course M. D. Anderson has a broad portfolio of prevention trials. Some examples if were able to identify women increase for breast cancer we're able to understand the disease on a molecular level then were able to use medicines to try and blunt that risk.

Zwelling:

What would that be? What specific risk factors are in that group of women and what therapies do you try to introduce to change their risk?

Hawk:

Well in that particular study we base it on the Gail Model. The Gail Model is based on a variety of risk factors that come out of studies like Dr. Bondy was just describing. Mammogram graphic data, family history data, history about the hormonal status of that individual in the past um… we take women that are increase risk of breast cancer and in this case randomize them to a medicine that might blunt that risk in this case a atorvastatin cholesterol lowering agent that seem to have anti-cancer affects in animals as well as laboratory settings verse placebo follow them over a period of time and find out if the medicine does increase factors that are important in breast cancer development.

Zwelling:

This is one of those rare cancer trials in which placebo arm is actually acceptable then.

Hawk:

A placebo arm is not only acceptable, really important because we really the medicine that were giving will actually be effective, it may actually cause side effects as well. Having that pure control arm to compare outcomes is really important in these sorts of studies.

Zwelling:

Have there been other studies that people have done that have shown that the intervention, the chemoprevention, has actually made a difference in the past, and is that now incorporated into medical practice?

Hawk:

Yes, approximate nine medicines that have been approved by the FDA, conducted through randomized trials such as we are describing here, and taken to the FDA. The independent regulatory body and proven safe and effective for use greater then the average risk individual. So people with higher risk for cancer um… there are two medicines used for breast cancer risk reduction. Tamoxophin as well as Reloxafine a whole variety of other agents useful either in collecting the development of cancer or treating pre-cancerous lesions cause the development of cancer is process that takes typically decades to occur usually proceeded by a pre-cancerous stage.

Zwelling:

And once the FDA has approved a cancer prevention therapy, is it likely insurance companies will pay for that?

Hawk:

Well in most instances, yeah. If it’s been FDA approved it become a medical practice insurance companies typically will reimburse for that treatment one the big challenges creating that evidence space that allows us to go and make that case and that’s why participating in research such as we’re discussing here today is so critically important.

Zwelling:

Right, that’s exactly what we wanted to show. There is a flow of information from what Dr. Bondy described as an observational study. Identify a particular question that can be address in a clinical trial doing the clinical trial getting the drug that been identified as a chemo-preventive agent approved by the FDA and then it will be paid for. So that sort of the model for what’s going to happen. In the cohort study Mexican-American cohort study are there any more chemoprevention strategies introduced yet?

Bondy:

No we haven’t , we're still in the early stages trying to build a cohort and identify a large enough population so that we can begin to look at specific diseases that could be important in different types of cancer. Then we could move forward and understand some of the genetics factor as well cause I think as we are moving forward and in understanding certain um… diseases it important to understand there may be different genetic factors that are important of modulating some of these pharmaceutical drugs.

Zwelling:

The biggest question I think that people always had about prevention and of course this the non-medical people and non-patients. Is the cost benefit of doing prevention of any kind. Is it thought at this point that this is actually a good idea and were introduce this more into the practice of medicine?

Hawk:

I would say absolutely we can follow the example of cardiovascular colleges that you mentioned in your introduction for example. Over the last fifty years they started of course treating patients with myocardial infarctions you know with heart attacks, with strokes and placing them in cardio care units and giving medicines kind of after the fact. Progressively they began to realize that things like high blood pressure or high cholesterol levels of family history impact on individual risk evolving to those events and begin to transform those risk factors into diseases themselves. You may be aware the whole public awareness went on in the 80’s and 90’s turning hypertension or high blood pressure into quote the silent killer. That sort of focus and attention both by the lay public as well at health practitioners begin to turn the tide and what the result was cutting the risk of cardiovascular disease outcomes heart attacks, strokes other important life events more than half. In the public that period in time so the success there and the path they followed is really what we trying to do with cancer today.

Zwelling:

How do you push that in the offices in the general practitioners, cause after all we're addressing people who are mostly healthy. So got to get the patients in contact with their practitioners, so there’s an element of marketing of this strategy is there?

Hawk:

There is if you think about cardiovascular disease it started by identify people at risk by doing simple test were hoping things like blood pressure monitoring and simple blood test. We're hoping to be able to do the same thing in cancer but of course were dealing with broader array of diseases when we talk about cancer and so it not quite as straight forward as it was there but first of all identifying people at risk . Secondly, understanding the disease well enough you can begin to target the things that are driving disease progression. That’ what we're doing in cancer prevention as well and then thirdly focusing on in points in our clinical studies in our clinical trials that are feasible in a relatively short period of time. So rather then targeting mortality reduction. Reducing people of dying of heart disease the first steps were to figure out whether your reducing cholesterol levels, reducing blood pressure those sorts of steps on who’s at risk, how you can intervene and how you determine success is exactly the path we're following in cancer prevention as well.

Zwelling:

I'd like to thank you.

Bondy:

Ah…I’d like to say one thing.

Zwelling:

Would you like to say one more Dr. Bondy? Go ahead.

Zwelling:

The important thing that money that much of the information Dr. Hawk is talking about came from a very important cohort study call the “Framingham Study.” Which is a population based study in the city of Framingham, Massachusetts and is still going on today. But that’s where we became aware that smoking was a risk factor for cardiovascular disease, and much of the work Dr. Hawk is talking about resulted from some of that early work.

Zwelling:

So again observational studies, clinical trials into practice, getting the insurance to pay for it .

Well thank you both Dr. Hawk and Dr. Bondy for your time. Listeners if you have any questions about anything you heard today regarding cancer prevention or the Mexican-American cohort please contact M. D. Anderson at 1-877-MDA-6789 or online www.mdanderson.org/ask. Thank you for listening this episode of Cancer Newsline. Again this is a weekly series please tune in again next week for our next episode of this series. You can do so by visiting www.mdanderson.org/newsroom and click subscribe from the menu. Or subscribe for free through Apple iTunes and the M. D. Anderson iTunes University page you can get there directly by typing www.mdanderson.org/itunes . Thank You.

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