WASHINGTON (AP) - Women who have had silicone breast implants do not face an increased risk for most cancers, according to a National Cancer Institute study of 13,500 women who had implant surgery for cosmetic reasons.

``The findings are generally reassuring,'' said Dr. Louise A. Brinton, an NCI researcher and lead author of the study. ``This does not raise a red flag. It helps lay to rest much of the concern'' about silicone breast implants.

The study, published in the Annals of Epidemiology, compared the incidence of cancer between women who had received cosmetic breast implants and 4,000 other women of similar age who had received other types of plastic surgery. Health histories for the patients covered an average of 13 years, much longer than most of the earlier breast implant health studies, said Brinton.

Early studies had shown that a comparison between breast implant patients and those receiving other cosmetic surgery was the best way to determine the specific effects of the silicon implants, she said.

Incidence rates for ``nearly every cancer'' were not elevated among the implant patients, Brinton said. This included cancers of the mouth, stomach, large intestine, breast, cervix, uterus, ovary, bladder, thyroid, connective tissues and immune system.

Brinton said there were slightly elevated rates of cancer for the respiratory system and brain, but she said there is no clear connection between these cancers and the silicon implants.

Only the difference in respiratory cancer rates reached ``statistical significance,'' said Brinton, principally because of lung cancers.

She said there were 33 lung cancers among the implant patients, compared to 13 among the other cosmetic surgery patients, but the connection of this cancer to implants is not clear.

Brinton said the cause of death for these patients was obtained from death certificates and it was not possible to determine the smoking habits of the deceased. Smoking is known to be the leading cause of lung cancer.

``We could not rule out smoking as a factor'' in the lung cancer deaths, said Brinton.

Between 1.5 and 2 million women have received breast implants since 1962, about 80 percent for cosmetic reasons and the rest as breast reconstruction after cancer. The study did not include women who had received implants following breast cancer.

The study follows an earlier study that found no increased risk for breast cancer among patients who received implants. Further analysis of the study data will evaluate risks linked to other causes of death and to the risk of connective tissue disorders among implant patients.

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