Mammogram may not detect tumors when women are in their 40s

Scientists are reporting in a new study that mammography is not an effective screening tool for women in their 40s because a tumor and the patient's tissue appear to be the same color.

Stanford University researchers reporting in the Journal of the National Cancer Institute said while the screening technique works best for women older than 50, the denser tissue of younger women tends to obscure tumors.

For years, doctors have known that tumors and dense tissue tend to appear white on a mammogram. In women who have undergone menopause, breast tissue often appears gray on a mammogram, so the sharp color contrast of the tumor is not as difficult to miss.