9 Janvier 2007

Implants may skew mammograms

Mammograms are less likely to detect breast cancer in women with breast augmentation than they are in women who have not had the implants, Seattle researchers have found.

A study led by Group Health Cooperative's Center for Health Studies found that mammography missed 55 percent of breast cancers in women who had surgical implants for augmentation, compared with 33 percent in women who didn't have the implants.

"Women with these implants need to be extra careful ... They shouldn't be too reassured by a negative (mammogram) result, and if they feel a lump, they should contact their physician," said Diana Miglioretti, a Center for Health Studies investigator and lead scientist in the research reported in today's edition of the Journal of the American Medical Association.

Miglioretti said implants show up as a solid, white mass on mammography film and make it more difficult to see some of the tissue.

Breast augmentation — the use of surgical implants for cosmetic reasons — is increasing. More than 268,000 women in the United States received implants in 2002, an 11 percent increase over two years, according to the American Society of Plastic Surgeons. Figures on the number of Washington state implants were not available.

The researchers did not find any more false positives in the women with implants than in those without. Nor were the cancers found in women with implants more advanced, despite mammography's decreased ability to detect tumors in those women. Miglioretti didn't know the reason.

With the help of six other medical institutions and funding by the National Cancer Institute, researchers collected data on 1.7 million women who had mammograms in Seattle, Colorado, New Hampshire, New Mexico, North Carolina, California or Vermont.

Among these women, they found 137 with implants who had developed breast cancer, and compared them with 685 women without implants who had the disease. They then determined which proportion of cancers in each group was detected by mammography.

Miglioretti emphasized the importance of regular mammography for women, which is recommended for women beginning at age 40. It did catch 45 percent of the cancers in the women with implants, and 67 percent in those without implants, she said.

Cancers in women without implants likely were missed, Miglioretti said, because a large proportion were younger women with dense tissue. Mammograms do not detect tumors as well in dense tissue.

Still, mammograms are an important tool in cancer detection. "It is important to find cancers in the earliest stage, so there is a better chance for survival," Miglioretti said.

Silicone implants will be available to women only through studies conducted by manufacturers to assess safety and effectiveness. Saline implants are available on the general market. When they rupture, the saline water is absorbed by the body; when silicone implants rupture, the gel can get stuck in tissue.