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Focus on 'Prevention' Divides Cancer Experts


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http://www.nytimes.com/2004/01/11/healt ... ml?ei=5062

Focus on 'Prevention' Divides Cancer Experts


he 2,000 people, the worried well, who come each year to Memorial Sloan-Kettering's cancer prevention center will learn that many cancers can, in fact, be prevented, and that it is up to them to have the appropriate medical tests and to live right.

For their $2,000 fee, most of which is paid by health insurance, they may be steered to smoking cessation sessions, or watch a cooking demonstration and hear a talk by a nutritionist. They will learn the early signs and symptoms of cancer and they almost certainly will have a cancer screening test.

"There is a lot that can be done to prevent cancer and detect it early," said Dr. Moshe Shike, the center's director. "We could probably cut cancer mortality by 50 percent."

Stopping smoking can prevent many forms of cancer, and changes in diet and weight loss also may have a marked effect. And while screening may find only cancer that is already present, it can save lives by catching it early.

Cancer prevention has become a buzzword these days, with some medical centers, like M. D. Anderson Cancer Center in Houston, planning entire buildings just for prevention. Its center will open in about a year, big as eight and a half football fields.

But even cancer experts who are participating in the new prevention efforts are divided on what really can be done to prevent cancer, other than stopping smoking. Looking at the same data on prevention, some experts say that for now most efforts involve research that may or may not lead to clinical advances.

That is a problem emblematic of the fiercely competitive world of cancer medicine, doctors say. Medical centers need to attract patients and federal research money. And that means they need to be on the cutting edge of the field. The National Institutes of Health requires medical centers that are designated comprehensive cancer centers, and eligible for its grants and contracts, to have a prevention component. The institute devoted $500 million, or 12 percent of its budget, to cancer prevention and control.

But, some ask, how can an honest message be communicated to the public about what can be done?

"I am concerned," said Dr. Donald Berry, a statistician at M. D. Anderson. "Most of what this is about is research. I think we're really early on in the cancer prevention area. Knowing what to do, knowing what the risk factors are and knowing when to intervene and how to intervene — we're not there yet."

He and others worry that many people greatly exaggerate their cancer risk and have inflated expectations of what science can do to protect them.

"We created the fear that everything is carcinogenic," said Dr. Michael Gallo, associate director for cancer prevention and control at the Cancer Institute at the Robert Wood Johnson Medical School. At the same time, he added, medical researchers "have convinced people that there is a magic bullet for everything." The result, he said, "is self-defeating."

At M. D. Anderson, for example, more than 80 percent of the cancer prevention center's budget is for research, which can range from basic laboratory work to epidemiology to clinical trials testing ideas of how to prevent cancer, said the center's director, Dr. Bernard Levin. Most people who come looking for ways to protect themselves against cancer are steered to the center's smoking cessation programs if they are smokers: a third of cancer patients there have smoking-related cancers. They are also offered screening tests.

Such strategies are hardly revolutionary, Dr. Gallo said. "It's what we've been doing for years. But it's sexy to be called the center for cancer prevention."

Dr. Otis Brawley, associate director for cancer control at the Winship Cancer Center at Emory University, shared Dr. Gallo's view. "To be politically correct as a cancer center you have to be interested in prevention," he said. The government expects it and so do patients, he added. "It is like a lot of things in medicine where we have implied success where actually there is very little."

Not everyone would agree. At Memorial Sloan-Kettering in New York, which offers diet and nutrition counseling and even cooking classes, cancer screening, genetic counseling and, of course, smoking cessation programs, the feeling is that there are great opportunities.

"There is a lot that can be done to prevent cancer and detect it early," said Dr. Shike, director of the cancer prevention and wellness program at Memorial Sloan-Kettering. "My feeling is that the general public and the medical profession don't take advantage of all the things we can do."

That depends on how you view the evidence and on what you mean by prevention, said Dr. Barnett Kramer, director of the office of disease prevention at the National Cancer Institute.

One potential source of confusion, he said, is that cancer prevention centers include screening. But screening, with a few exceptions like colon cancer and cervical screening that find and remove precancerous growths, looks for cancer that is already present. That may or may not save lives, Dr. Kramer said, depending on whether the treatment is effective and whether the cancer would have been deadly if it had been left alone, undetected.

Not all cancers will spread and kill, and sometimes the outcome is the same whether a cancer is found earlier or later. But with screening, doctors treat any tumors they find because they cannot tell which are worrisome and which are not.

In the end, screening, far from preventing cancer, actually leads to more cancer patients, Dr. Kramer noted, by finding both those whose cancers would have been deadly and those whose cancers would never have been a problem because they would have remained small and never spread, or would even have disappeared.

"People often talk about mammograms to prevent breast cancer when what it's done is to increase, not decrease, the incidence of breast cancer," Dr. Kramer said.

Many people decide to take their chances with screening, reasoning that they would rather be treated for a cancer that would not have killed them than to miss being treated for a cancer that could be lethal. But it is not easy to know if screening helps or harms over all, Dr. Kramer said, adding that it requires large controlled trials. Such studies, he noted, have not yet been completed for some popular tests, like the P.S.A. test for prostate cancer and spiral CT tests for lung cancer.

As for genetic screening to see who is susceptible to cancer, that is still in its infancy, Dr. Berry said. There are a couple of genes that predispose to breast cancer and a couple that predispose to colorectal cancer. "Not much is known beyond that," he said. And other than taking tamoxifen to prevent breast cancer or having one's breasts, ovaries or colon removed to prevent cancers in those organs, what does someone do who is genetically susceptible? Another research question, Dr. Berry said.

When it comes to other prevention strategies, like diet, Dr. Kramer said, "it gets a lot trickier." He urges caution in jumping to conclusions that specific foods, or diets, or even weight loss will be protective. Researchers often find associations between diets and cancer risk, but that does not mean that a particular diet or food caused or prevented cancer, he said. The history of research in this area has been sobering.

For example, study after study found that people whose diets were high in beta carotene had a lower incidence of lung cancer. But in studies in which smokers and former smokers took beta carotene supplements, it turned out that the vitamin actually increased lung cancer risk and lung cancer deaths. Studies found associations between high-fiber diets and reduced incidence of colon cancer. But a large study that randomly assigned some subjects to high-fiber diets found no reduction in cancer or in polyps, the growths that can precede cancer.

At Memorial Sloan-Kettering, Dr. Shike said, patients are taught how to eat healthy diets and even go over their diets food by food with a nutritionist and a computer program, but are not told that diets are a panacea. "We are not saying you can prevent cancer with a healthy diet, but we say a healthy diet and a healthy weight are part of a healthy lifestyle, which can help lower your risk."

Dr. Berry has a different view of cancer prevention centers. For now, while research continues, perhaps their greatest value to healthy people is not so much in giving them ways to prevent cancer but in showing them that their fears of getting cancer may be exaggerated and that if they do develop cancer, it usually is not because they did something wrong.

"The person in the street greatly exaggerates their risk of cancer," Dr. Berry said. One thing a cancer prevention center can do, he said, is let people know their real risk and the real effect of measures that many think will give them cancer, or protect them from it.

"We can be letting them know that changing their lifestyle may change their risks, but not by much," Dr. Berry said. "We can be letting them know that while hormone therapy may increase the risk of breast cancer, it does not increase it much."

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