Sonography Superior for Some Breast Cancers
More accurate than mammography for women under 45 with symptoms
FRIDAY, March 21, 2003 (HealthDayNews) -- Mammography may be the standard screening test for breast cancer, but if you're a woman under 45 with symptoms of the disease, an ultrasound is more likely to find malignancies.
That's the conclusion of a new study published in the April issue of the American Journal of Roentgenology.
"Sonography was significantly more accurate than mammography in diagnosing breast cancer in women with breast symptoms who are 45 years and younger," says study author Dr. Nehmat Houssami, a senior lecturer at the School of Public Health at the University of Sydney, Australia. Houssami was the director of the MBF Sydney-Square Breast Clinic at the time the study was conducted.
Houssami is quick to point out, however, that the study did not look at general-population screening for breast cancer, and he says he is definitely not suggesting that ultrasound replace mammography for screening.
Every year, 180,000 American women are diagnosed with breast cancer, according to the National Cancer Institute. Symptoms of the disease include a lump in the breast, nipple discharge, pitting or ridges in the breast, or changes in the size, shape or appearance of the breast.
Mammography is an X-ray of the breast, and the American Cancer Society recommends that every woman over 40 have a mammogram annually. Ultrasound images are generated by sound waves.
For this study, radiologists examined the mammograms and sonograms of 480 women between the ages of 25 and 55. All of the women had symptoms of breast cancer. Half of the women actually had breast cancer. The 240 women without cancer were age-matched to those in the breast cancer group.
Overall, there was not a statistically significant difference in the detection of cancer between the two tests, they found. However, in younger women -- those under 45 -- sonography correctly identified 84.9 percent of breast cancers, while mammography was only able to pick up 71.7 percent of the cancers.
The reason for the difference, Houssami says, is simple. Younger women's breasts are generally more dense than older women's breasts, and sonography is better able than mammography to capture images through that density.
In most cases, a woman with breast cancer symptoms is referred for both mammography and sonography, regardless of her age, according to the study.
For all the age groups combined, researchers in this study found that 96 percent of the cancers were detected using both tests together, versus 81.7 percent for ultrasound alone or 75.8 percent for mammography alone.
Dr. Diane Palladino, a breast surgeon at Exeter Hospital in Exeter, N.H., says she always orders both tests for a woman who has symptoms of cancer, explaining that both tests have their strengths and weaknesses.
"Ultrasound helps us judge the size of the lesion and can give us some idea of whether the tumor is benign or malignant," she says, adding that ultrasound provides better images of denser breast tissue than mammography does.
But, she says, ultrasound can't see microcalcifications, which are signs of very early breast cancer.
Eventually, both Houssami and Palladino think ultrasound may become the main imaging test for detecting breast cancer in younger women after further research is done.
Palladino says it's important for women to realize "that mammography is not 100 percent, especially in younger women. If you have a lump and a negative mammogram, you still need to address that lump in your breast."