DATE: Tuesday, November 4, 1997             TAG: 9711040281

SECTION: FRONT                   PAGE: A3   EDITION: FINAL 

SOURCE: ASSOCIATED PRESS 

DATELINE: WASHINGTON                        LENGTH:   68 lines

STUDY SHEDS LIGHT ON HOW EXPOSURE TO THE SUN CAN HELP PREVENT BREAST CANCER

Basking briefly in the sun every day may be an important way to prevent breast cancer, researchers said Monday. But they also warned, ``Don't overdo it.''

New studies indicate that vitamin D, a nutrient made by the skin during exposure to sunlight, can reduce the risk of breast cancer by 30 percent to 40 percent and perhaps even more.

``We know now that a little bit of sun is beneficial, but it is not good to stay out there four or five hours,'' said epidemiologist Esther John of the North California Cancer Center. ``We don't want to recommend that people go out and bake in the sun.''

She said it is well known that excessive exposure to sunlight can cause skin cancer and premature aging of the skin.

John, in a study presented Monday at a meeting of breast cancer experts, said that a study comparing the health habits of 133 breast cancer patients with women who did not have the disease found that exposure to sunlight significantly reduced the risk of breast cancer.

Sunlight lowers the risk, said John, because the skin uses ultraviolet rays from the sun to make vitamin D. This nutrient has been linked to protection against breast cancer in other studies, she said.

The study was part of a national research project that has been following the health of about 8,000 women since 1970. The research monitors the development of cancer and other health events, and compares the effects of such things as diet and exercise of women who get disease and those who don't.

John said that the study confirmed earlier findings that women who live in the southern tier of states below Kansas tend to get significantly less breast cancer than those who live in the North.

The difference, she said, is sunlight and how the skin makes vitamin D. Southern states have more year-round sunlight than northern states do. As a result, people in the South get more natural ultraviolet ray exposure.

For instance, John said that winter sunlight is so weak in the North that people living at or above 40 degree North latitude do not get enough sun from November to February to make the required levels of vitamin D. Boston is at latitude 42 degrees.

John said the study did not determine just how much sun exposure is needed to protect against breast cancer, but she said it probably is less than what would cause skin damage.

``It is possible that all it takes is 10 or 15 minutes outside in bright sunlight to get a benefit,'' she said. ``But we don't really know that yet. There needs to be more study.''

Sunscreen lotions that block ultraviolet rays would also block the formation of vitamin D, she said.

Vitamin D can also come from the diet, said John. The vitamin is available naturally in fish oil, fatty fish, egg yolk and liver, all foods that few Americans eat, she said. Milk and some cereals and breads are fortified with vitamin D.

``If they depend on food only for vitamin D, women would have to eat foods with at least 200 international units a day to get a reduction in breast cancer risk,'' she said.

Three and half ounces of canned tuna, salmon, sardines or mackerel all contain more than 200 IU of vitamin D, according to Agriculture Department nutrition figures.

John said it is not known if vitamin D pills can provide a level of the nutrient to protect against breast cancer.

Dr. Dennis J. Slamon, a cancer doctor at the University of California, Los Angeles, said the vitamin D study by John supports earlier studies that showed sunlight and vitamin D lower breast cancer risk. KEYWORDS: SUNLIGHT BREAST CANCER

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