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Certain Factors May Cut Ovarian Cancer Risk

They include bone fractures, contraceptive use, researchers report

WEDNESDAY, May 11, 2005 (HealthDay News) -- An odd constellation of factors, including whether a woman has had a bone fracture or used contraceptives, may be associated with a reduced risk for ovarian cancer, a new study finds.

Any one of these factors may give the body enough armor in the form of antibodies to fight off the cancer before it begins. And although the finding is preliminary, it may lead to ways to prevent ovarian cancer, the researchers said.

"You could conceive a vaccine that would prevent ovarian cancer," said Dr. Daniel W. Cramer, lead author of the study that appears in the May issue of Cancer Epidemiology, Biomarkers & Prevention. Cramer is with Brigham and Women's Hospital in Boston, and conducted the study in collaboration with researchers at the University of Pittsburgh and Dartmouth-Hitchcock Medical Center.

Still, it's not clear where the protective effect may be coming from, said Dr. Jay Brooks, chairman of hematology/oncology at the Ochsner Clinic Foundation in New Orleans. It could be there is an "immunological event" that could predispose women to develop ovarian cancer. Or the researchers may be seeing an immunological response to something else in the body having nothing to do with the cancer, he said.

If detected in its early stages, ovarian cancer can be treated effectively. In reality, however, the disease is usually caught in its later stages, when the cure rate drops to 15 percent to 20 percent. It is the fourth-leading cause of cancer death among women in the United States, the researchers noted.

The American Cancer Society estimates there will be about 22,220 new cases of ovarian cancer in the United States in 2005, and about 16,210 women will die of the disease.

While much research has focused on finding better screening methods for ovarian cancer, there has also been interest in reducing risk for the disease.

Researchers already knew that women with ovarian cancer who have antibodies to a protein called epithelial mucin 1 -- or MUC1 -- had better odds for survival.

MUC1 is one of several proteins that are overproduced in ovarian cancer. The protein is also present in some healthy individuals.

"MUC1 is a very important protein in the body, and is expressed in many different cells of the body," Cramer explained. "When one of those cells becomes cancer, it begins to overexpress MUC1."

The question was whether MUC1 also plays a role in preventing ovarian cancer.

"It's been known for many years that women who have cancer and who have MUC1 antibodies actually have a more favorable prognosis," Cramer said. "We reasoned that if women had developed the antibodies before the cancer, that might have prevented it from developing in the first place."

For this study, the researchers measured anti-MUC1 antibodies in 705 women without ovarian cancer and assessed the events that would produce antibodies. They then evaluated 668 women with ovarian cancer to see how frequently they had had antibody-producing events.

Women were more likely to have anti-MUC1 antibodies if they had: used oral contraceptives; had breast mastitis (an infection common in breast-feeding women); bone fracture or osteoporosis; pelvic surgery such as tubal ligation or Caesarean section; refrained from using talc in genital hygiene; used an IUD birth control device; or currently smoked.

Women who had none or one of these factors had a 24.2 percent likelihood of having the antibodies; those with five or more of the factors had a 51.4 percent likelihood of having the antibodies, the study found.

Women who had had breast mastitis had a 65 percent lower risk of ovarian cancer compared with women who did not breast-feed. Women who used an IUD, as well as women who had fractured a bone, had a 30 percent reduced risk compared with women who did not use IUDs or had had no fractures.

The study, the authors acknowledged, is just the beginning. "This presents a new paradigm for ovarian cancer, in terms of immune factors that might be playing a role," Cramer said. "We want to see if we can find data sets in which we have blood taken years or decades before cancer."

The findings may also have relevance for other cancers, because MUC1 is expressed by a wide range of cancers including breast, endometrial and pancreatic cancers, he said.

More information

Visit the National Cancer Institute for more on ovarian cancer.

SOURCES: Daniel W. Cramer, M.D. ScD., obstetrician/gynecologist, Brigham and Women's Hospital, and professor, obstetrics and gynecology, Harvard Medical School, both in Boston; Jay Brooks, M.D., chairman, hematology/oncology, Ochsner Clinic Foundation, New Orleans; May 2005 Cancer Epidemiology, Biomarkers & Prevention
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