NEW YORK, Mar 26 (Reuters Health) - Women with silicone breast implants do not appear to be at increased risk for an immune system abnormality called monoclonal gammopathy of undetermined significance (MGUS), results of a new study suggest.

Past evidence had suggested a link between exposure to silicone gel and MGUS, as well as a type of cancer called multiple myeloma.

After a review of the medical records of 288 women who had breast implants and 288 women of similar ages who did not have implants, Dr. Elizabeth W. Karlson and colleagues from Harvard Medical School in Boston, Massachusetts, found no evidence that the implants increased MGUS risk. Their report is published in the March 26th issue of the Archives of Internal Medicine.

Nine cases of MGUS were reported in all. Five were in the breast implant group and four were in the non-implant group. Women with breast implants who developed MGUS tended to be about 8 years older than those without the implants.

"We find little evidence to support a substantial increased risk of MGUS in women (with) breast implants. Larger studies are needed to determine if a more modest relationship exists," the authors write.

In MGUS, abnormal plasma cells produce an excessive amount of antibody protein, but do not form a tumor or mass and do not cause any symptoms, according to the American Cancer Society. While MGUS usually has no impact on a person's health, the society notes, about 20% of people with MGUS will go on to develop multiple myeloma or a closely related cancer of their B-cells, malignant lymphoma, within 20 years. Patients with MGUS usually need frequent medical examinations and tests to detect possible progression to multiple myeloma, but generally do not need any immediate treatment.

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