Researchers Look for New Weapons in Fighting Cancer, Heart Disease

Two big killers will count their victims in the millions in the 1990s--13 million American lives claimed by heart disease and cancer if the current fatality rates continue.

But medical researchers hope to strike some telling blows against these deadliest enemies in the coming decade. They don’t expect cures; instead, they’re looking for new insights to help them attack the diseases from many directions.

A better understanding of cancer-causing genes and how to block them, and of cancer-suppressing genes and how to harness them, would give medical scientists crucial new weapons to wield against cancer, which will kill an estimated 500,000 Americans this year.

And new discoveries about the relationship of diet to heart disease might lead to innovative treatments for the nation’s leading killer, which killed 767,000 Americans in 1988--about one-third of the deaths from all causes.

Just about everybody has heard about eating right to avoid high levels of cholesterol in the blood. Cholesterol can promote atherosclerosis, a narrowing of the arteries that sets the stage for heart attacks.

But in this decade, “We may learn that what you eat is more important than just what it does to your cholesterol,” said Rodman Starke, the American Heart Assn.’s senior vice president for scientific affairs.

“We are beginning to see glimmers of evidence” that some dietary substances may affect atherosclerosis risk independent of any impact on cholesterol, he said. They may also promote blood clotting, which can cause heart attacks when it occurs in narrowed arteries that feed blood to the heart muscle, he said.

Scientists may also find better ways to prevent heart attacks as they learn more details about what triggers them in people with atherosclerosis, said James Willerson, chairman of the heart association’s research committee.

He also said researchers may find a way to identify people at risk for sudden cardiac death, a lethal disruption of the heart’s pumping rhythm, and develop better techniques to prevent it.

Other potential developments Starke or Willerson suggested for the 1990s include:

* Greater understanding of the complex events that produce atherosclerosis, perhaps leading to treatments to reverse or avoid it.

* Improved clot-dissolving drugs to stop heart attacks. Researchers would like to reduce side effects, confine the anti-clotting effect to places where it will do good, and stop the effect of the drugs when needed to avoid the risk of excessive bleeding.

* Better understanding and possible prevention of a re-narrowing of atherosclerotic arteries after a procedure called angioplasty is used to widen them. This occurs in 25% to 40% of patients who go through angioplasty and is a major stumbling block to the procedure’s success, Willerson said.

As with heart disease, some of the advances experts hope for in the fight against cancer in the 1990s deal with prevention.

Researchers may find genetic tests to identify people at high risk for cancer of the colon or breast, and probably some other common cancers as well, said John Laszlo, the cancer society’s senior vice president for research.

Warnings and instructions about prevention should pack more wallop for those people than the blanket recommendations now given to everybody, he said.

“When you’re talking about the possibility of changing your diet for your lifetime, it would be nice to know ahead of time whether it would be important for you to do that,” Laszlo said.

Another payoff in identifying people at particular risk for certain cancers would be the ability to learn more about the effectiveness of preventive steps, said Vincent DeVita, former director of the National Cancer Institute .

If experiments can be focused on people at high risk, researchers can get better information on how much of a diet or lifestyle change is needed, and for how long, in order to cut cancer risk, said DeVita, who is physician-in-chief at the Memorial Sloan-Kettering Cancer Center in New York.

He and Laszlo also expect progress in making chemotherapy more effective by sabotaging the ability of some cancer cells to resist it. That could help treatment of many kinds of cancers, and particularly those of the breast, colon and pancreas, they said.

Among the other possible developments in the 1990s suggested by DeVita or Laszlo:

* The first experiments in people with “anti-sense” DNA, substances designed to block the effect of cancer-causing genes.

* Routine use during chemotherapy of recently discovered colony-stimulating factors, allowing higher doses of medicine. The substances counter a major side effect of chemotherapy: decreases in infection-fighting white blood cells.

* Advances in the use of monoclonal antibodies, molecules that can seek out and bind to cancer cells, to deliver radiation treatment or to keep cancer cells from responding to substances that spur their growth.

* More research into suppressor genes, which act to prevent development of cancer. Perhaps the substances they direct cells to make can be harnessed to fight cancer, DeVita said.

“Theoretically it should work, and technically there’s no reason it can’t be done,” he said. “So stay tuned.”