Mammograms: Traditional Versus Digital

Physicians use mammograms in two ways: to screen women who have no signs of breast cancer and as a diagnostic tool to check for cancer after a woman or her physician notice other symptoms. The medical community has long advised women to begin screening for breast cancer at age 40 unless they have known risk factors, such as a family history of cancer.

Until recently, the traditional mammogram was the gold standard for breast cancer screening. Today, digital mammograms are also an option.

How are Mammograms Used?

A mammogram can detect tumors that are too small to feel through a self-breast exam. It also reveals tiny deposits of calcium and abnormal cells in the breast ducts that may someday become cancer. The effectiveness of a mammogram depends on the size of a tumor, the density of the breast tissue and the radiologist's skill in reading the results.

Mammograms have limitations, of course. Just because the procedure detects cancer doesn't necessarily mean it will save a woman's life, especially if she has a fast growing or particularly aggressive cancer. Mammograms also produce false negatives (normal reading despite presence of cancer) and positives (abnormal reading but no cancer). Recently, researchers reported that one out of three breast cancer detections were over-diagnosed and over-treated. This means the cancer grows so slowly that a patient dies of other causes before the breast cancer becomes a problem. Mammograms miss, on average, about 20 percent of cancers.

What's the Difference

In a traditional mammogram, a health professional takes X-rays of a woman's breasts. The X-ray images are stored on film and read by a qualified radiologist.

Like a digital camera, a digital mammogram is an electronic image of the breast that is stored on a computer. The primary advantage of digital mammography is that the radiologist can magnify or manipulate the image, providing him or her with more information, which leads to fewer follow up mammograms. Digital mammograms also make it easy for physicians to consult with specialists remotely, if needed.

Which is Best?

That depends. In 2005, the National Cancer Institute reported the results of the Digital Mammographic Image Screening Trial (DMIST), a study evaluating the effectiveness of digital mammography in almost 50,000 women who had no signs of breast cancer. The researchers found that in the general population there was no benefit to digital mammograms. However, in pre-menopausal women with dense breasts, or women under 50, digital mammograms provided an advantage over traditional mammograms.