CHECKUP : NEWS, TIPS AND TRENDS A NEW STUDY ON MAMMOGRAMS.

A yearly mammogram is the most effective method of detecting breast tumors in women ages 50 and older, a new study finds.

But in women ages 40 to 49, the breast X-rays are less likely to spot a tumor, and the risks of the screening may outweigh the benefits, according to California researchers.

The new findings, published last week in the Journal of the American Medical Association, most likely will re-ignite the debate over screening guidelines for breast cancer.

While most experts agree that women 50 and older should go for mammograms regularly, they are less certain about whether women in their 40s should undergo mammography.

The American Cancer Society currently recommends that a woman get her first mammogram at age 40, followed by one every one to two years thereafter.

However, the group is considering changing its recommendation to yearly mammograms beginning at age 40, according to Robert Smith, senior director in the department of cancer detection and treatment at the American Cancer Society in Atlanta.

The National Cancer Institute no longer has screening guidelines for any type of cancer, according to John Gohagan, chief of the early detection branch at the National Cancer Institute in Bethesda, Md.

``The public pays $2 billion a year to the National Cancer Institute and they do not want guesses,'' he said. More studies are needed before guidelines can be issued, he added.

Better late than never: It may never be too late to stop smoking, begin exercising or make other heart-healthy lifestyle changes, researchers report.

In a new study of 4,736 Americans ages 60 or older with high blood pressure, those most likely to have a heart attack or experience some other heart-disease ``event'' within 4.5 years were smokers, diabetics, those with hardening of the arteries and those with high cholesterol.

``It is a reasonable inference that older individuals at high risk for a heart-disease event can benefit from smoking cessation, control of hypertension and cholesterol reduction,'' wrote the study authors, led by Dr. Philip H. Frost, of the Cardiovascular Research Institute at the University of California, San Francisco.

In the study, a heart-disease event was defined as a fatal or nonfatal heart attack, a heart-bypass surgery or an angioplasty.

``These results may be applicable to the more broad-based older population without hypertension,'' the researchers wrote.

Heart disease is the most common cause of death in men and women over 60, the researchers noted in the study, published in the journal Circulation.

``This study undercuts the theory that risk factors become irrelevant as you get older,'' said Dr. John C. LaRosa, a professor of medicine at Tulane University Medical Center in New Orleans. ``It's not OK for people to reach a certain age and assume that risk factors don't matter anymore,'' he said.``You shouldn't excuse someone from stopping smoking or changing their diet because they have reached 65.''