Is there a role for sonography in breast cancer screening?

Sonography can disclose tumors that remain mammographically occult. As a result, many have suggested to perform sonography in addition to screening mammography, especially in women with dense breasts. This approach, however, should be dealt with very cautiously. First of all, the term "mammographically occult" should be used carefully, because lesions that are missed because of suboptimal mammographic image quality or bad positioning or because no attempt has been made to compare with previous mammograms must not automatically be considered as mammographically occult. Secondly, introduction of sonography in mammographic screening is not straightforward because (1) it is extremely difficult to detect small malignant lesions with sonography without concurrently causing an excess of false positive results, (2) it is unclear how sonographic screening should be organized and quality-assured, (3) it is not unreasonable to expect that the excess costs of sonographic screening would favor other prevention strategies with more favorable cost/benefit ratio to decrease overall mortality. But most importantly, no large-scale trials have unequivocally proven the validity of sonography screening so far, neither in the general population, nor in subgroups with dense mammograms and/or at increased risk of breast cancer. Therefore, mammography remains currently the only screening tool that is associated with a decrease of breast cancer specific mortality and that should be used for mass screening.