• 9/9/2004
  • Louisvill, KY
  • By Linda Stahl
  • The Courier-Journal

Visiting expert says most cases can be avoided with diet and lifestyle changes

Dr. Bernard Levin, one of the nation’s foremost authorities on cancer prevention, will give a free public speech at the Hyatt Regency in Louisville tonight as part of a Norton Hospitals Foundation lecture series. Levin won the American Cancer Society’s 2004 award for a career devoted to the early detection and prevention of cancer. At the University of Texas M.D. Anderson Cancer Center, Levin has developed a broad research program that combines the study of behavior, genetics, chemotherapy and population groups to learn how to prevent cancer. He maintains that two-thirds of all cancers can be prevented through diet and lifestyle changes.

In advance of his visit, we spoke with him in a telephone interview from his office in Houston. Here are excerpts from the conversation:

What are the top six ways a person can reduce his risk and his family’s risk of getting cancer?

The first is related to tobacco. Stop or never start tobacco. Know your family history, because that could be very important in determining your own risk. The next is maintain a healthy weight. Keep physically active. The next is avoid unnecessary exposure to the sun. Age- and gender-appropriate screening.

Q: What does the American public need to learn to help the United States reach its potential for cancer prevention? What seems to be our greatest area of ignorance?

A: Health literacy. I mean by that understanding more about biology, having some grasp of what makes us tick and things that we can do to make ourselves healthier and things that we probably can’t exert a lot of influence over.

We tend to unfortunately focus on things that come at the end of life. We have fantastic intensive-care units and amazing interventions that are very costly, but if we spent the same amount of energy and time on earlier phases of disease, before cancer ever develops, we might experience greater gains with much less cost.

That’s one aspect. The other is to recognize there is a process for evaluating any intervention, including cancer prevention. So, reliance on some objective means of evidence.

Evidence-based medicine is very valuable. There are documents that would give us a clear understanding of what works and doesn’t work. Placing reliance on things that haven’t been proven always is risky.

Q: Such as depending on an unproven supplement?

A: Right. Exactly. Unproven supplements or unproven interventions of various kinds.

We already have good evidence that there are things that we can do and that are hard to do. It’s hard to give up smoking. We all know it’s hard. It’s hard to exercise. It’s also hard to maintain one’s weight.

So instead of that, we look for something that comes easily in a pill or in a sort of a magic potion, mostly that doesn’t exist.

Q: What can be done to help people change the things they do that are dangerous in respect to cancer? We’re hearing alarming reports now about rising obesity rates, especially among children.

A: I think it has to do with some very fundamental issues that start in early childhood and go through the adolescence and has a lot to do with the lifestyles that we choose for ourselves and which our kids emulate. So, obviously (the rejection of) tobacco and access to healthy eating, that has to be learned. You don’t just pick it up incidentally.

Maintaining healthy body weight is the converse of eating right. It’s difficult to maintain a healthy body weight by exercise alone. I suspect there are some people who can, but it’s a rarity. I think it has to do with a balanced diet and appropriate calories for one’s needs for one’s body size and expenditure of energy and choosing what we believe to be a healthy diet.

Although we recognize we don’t have all the answers on diet, a diet that is reasonable as to intake of fresh fruits, vegetables, fiber-containing foods, lower in red meat than probably is the average Texan diet — and maybe in Kentucky too — and doesn’t have too much alcohol — moderate alcohol — which is a dietary constituent, and is not too high in fat.

Q: Are any cancer-screening methods in danger of overuse or of exposing patients to harm — or using up precious resources that could be applied elsewhere in the fight against cancer?

A: Well, one of the ones that recently got attention in the newspaper was surveillance colonoscopy, where there was some concern that people who are at very low risk for recurrence of cancers or polyps (of the colon) were oversurveyed.

Screening is (testing of) asymptomatic people who have never had a diagnosis of cancer. Surveillance is the follow-up.

There is some concern about doing Pap smears on people who don’t have a cervix because they’ve had a total hysterectomy, that they probably don’t need Pap smears. So that’s another group.

Some concern about how useful it is to do mammograms on people between 40 and 49. It’s a very controversial area because they have more false positives. More people believe the benefits accrue to those 50 and older. I’m not saying it’s bad to do a mammography; I’m just saying it’s controversial. And certainly the area of PSA (prostate specific antigen) testing is controversial. It’s not a great test, and we need better tests. Even if you have a low PSA, you can have prostate cancer. A rising PSA is not a good thing, but with a normal PSA you can still have prostate cancer. So those are tests that have some controversy associated with them.

Q: What will be the next breakthrough in cancer prevention?

A: Two pathways I see. Understanding the molecular targets of how cancer develops and finding ways to intervene to prevent them are very powerful. That’s chemoprevention, and I will discuss that as well.

Chemoprevention is still reserved for very high-risk people, higher than average, people who have had a previous cancerous polyp in the colon or a precancerous lesion in the mouth, that sort of patient.

Chemoprevention is the use of compounds, natural or synthetic, to prevent cancer from developing or spreading. Let’s say someone has been smoking for years and has developed a white patch in the mouth, leukoplakia. Theoretically, if you could remove that surgically that might be enough, but we know that some of those white patches recur quite soon and some you can’t remove enough — you’d have to remove the entire jaw.

By targeting those individuals with special compounds that prevent cell growth, that is chemoprevention. It’s the chemotherapy of pre-cancer. There are lots of research trials on this now.

Better screening methods are also a valuable and likely possibility. We will be able to assess risk by looking at one’s genes or by looking for specific circulating proteins in the blood.

That’s being looked at in ovarian and other cancers. There’s been a flurry of interest in a product called OvaChek, not proven but it’s out, for looking for ovarian cancer markers (in the blood).

Q: Does cancer have a sex bias?

A: Obviously some cancers are gender specific. Women get breast cancer mostly. A few men do. Men only get prostate cancer, and women only get ovarian cancer. Of all the other cancers that occur, some have a more definite gender bias. Lung cancer has been more common in men, but women are catching up. Colon cancer is an equal opportunity cancer for both men and women, which is not well-recognized. Skin cancer may be a little more common in men, but not much.

Q: Does cancer have a racial bias?

A: There are some very distinct patterns, particularly with regard to African Americans. They tend to have a worse outcome on most cancers, and we really don’t know why, whether it’s late diagnosis or not enough access to screening and prevention, or whether there are some biological factors. It’s probably a mixture. Some cancers aren’t as common in Latinos, such as colon cancer.

Q: One of your specialties is cancer of the colon. What is the best way to prevent it and what is the best screening test for detecting it?

A: We don’t know one best way to prevent colon cancer.

For prevention, certainly the whole issue of body weight, exercise, diet and, for high-risk people only, perhaps the use of a non-steroidal anti-inflammatory drug (aspirin, Advil and Motrin are examples). Those would probably be the four ways that I would consider useful.

As to what’s the best screening, it actually depends a little bit on the circumstances and the individual and what’s available. The only screening method for which there is really strong evidence, randomized control-trial evidence, is fecal occult blood testing, testing for hidden blood in the stool. There is weaker evidence for flexible sigmoidoscopy (where a viewing instrument examines the lower colon). And there is only the weakest level of evidence for colonoscopy (where a viewing instrument examines the entire colon, not just the lower portion). Nevertheless, everyone seems to have latched on to colonoscopy for several factors because, No. 1, it can be done in sedated people so they don’t feel the consequences of any part of the procedure, which is not fun. It can possibly be done less frequently, maybe up to every 10 years, although we’re not entirely sure of that. There are two newer tests that have received a lot of attention — virtual colonoscopy and looking for altered DNA in the stool. Those are not proven yet and not in widespread use. Of the tests that are currently available, colonoscopy is the one that is probably most favored by gastroenterologists and by surgeons. Fecal occult blood testing is most favored by people who look at large populations.

Tests exist that are effective in detecting colon cancer. Don’t wait for something else. We already know how to do this.

Q: Are there any books you would recommend or Web sites for people interested in increasing their health literacy and understanding of cancer.

A: Yes, the one I think is most valuable because it is based on objective evidence is the National Cancer Institute PDQ service for both professionals and the public. (www.cancer.gov/cancer_information) Lists objective evidence for screening and prevention and treatment of the common malignancies and genetics too. That’s the gold standard.

Q: Anything else you’d like to say about cancer prevention?

A: People need to be better informed and need to discuss their options with their physicians. Don’t be shy, particularly in regard to colon cancer. We always say, “Don’t die of embarrassment.” If you have a question or if you have something, don’t hesitate.

Most primary-care physicians only have 15 or 18 minutes (per patient). Maybe it’s worth making a separate appointment to talk about cancer prevention, the same way you would make a special appointment to care for your car or your horse.