Women in their 40s, who tend to have relatively dense breast tissue, are more likely to have a breast tumor missed on a screening mammogram than are older women, new study findings suggest.

“Our study found that breast density is a cause of younger women having poor sensitivity of mammography compared with older women,” co-investigator Dr. Emily White told AMN Health.

However, this finding “would not lead to the conclusion that women with dense breasts should be screened more often,” she added.

White, at Fred Hutchinson Cancer Research Center in Seattle, and her associates studied 73 women ages 40 to 49 years and 503 women ages 50 or older who were diagnosed with invasive breast cancer between 1988 and 1993. Their results are published in the Journal of the National Cancer Institute.

Cancers that were diagnosed within 12 months after a negative or benign screening mammogram occurred in 28 percent of the younger women, but in only 14 percent of the women age 50 or older.

Other than menopausal status, traditional breast cancer risk factors, such as age at first menstruation and family history did not account for the reduced sensitivity of mammographic screening.

“At this point I think the radiology community probably needs a different modality to detect breast cancer in women with dense breasts,” White said.

The team hopes their data spur “further research to elucidate potential complementary imaging modalities,” such as MRI or ultrasound.

SOURCE: Journal of the National Cancer Institute, October 6, 2004.