Other research on BSE is limited. First, Leningrad investigators cluster-randomized more than 100,000 women to BSE training or control. The group that received BSE training had more breast biopsies but no improvements in breast cancer mortality. Second, in the U.K. Trial of Early Detection of Breast Cancer, two districts invited more than 63,500 women aged 45 to 64 years to educational sessions about BSE. After 10 years of follow-up, there was no difference in breast cancer mortality rates compared to those in women from centers without organized BSE education (RR = 1.07; 95% CI, 0.93–1.22). Third, and last, a case-control study nested within the Canadian NBSS compared self-reported BSE frequency before enrollment with breast cancer mortality. Women who examined their breasts visually, used their finger pads for palpation, and used their three middle fingers had a lower breast cancer mortality rates.
The primary role of ultrasound is the diagnostic evaluation of palpable or mammographically identified masses, rather than serving as a primary screening modality. A review of the literature and expert opinion by the European Group for Breast Cancer Screening concluded that "there is little evidence to support the use of ultrasound in population breast cancer screening at any age." In the setting of normal mammography and ultrasonography, less than 3% of women who have a lump will ultimately be found to have breast cancer.[18,19,20,21]
Magnetic Resonance Imaging
Breast magnetic resonance imaging (MRI) may be used in women for diagnostic evaluation, including evaluating the integrity of silicone breast implants, assessing palpable masses following surgery or radiation therapy, detecting mammographically and sonographically occult breast cancer in patients with axillary nodal metastasis, and preoperative planning for some patients with known breast cancer. There is no ionizing radiation exposure with this procedure. It has been promoted as a screening test for breast cancer among women at elevated risk of breast cancer based on BRCA 1/2 mutation carriers, a strong family history of breast cancer, or several genetic syndromes such as Li-Fraumeni or Cowden disease.[22,23,24] Breast MRI is more sensitive but less specific than screening mammography [25,26] and is more expensive.
Direct comparisons of breast MRI and mammography in young high-risk women report MRI sensitivities of 71% to100% versus mammography sensitivities of 20% to 50%. Contrast-enhancing foci are seen frequently in healthy breasts, so false-positive results are common.[27,28] In these studies, MRI specificities range from 37% to 97%, with threefold to fivefold higher recall rates and substantially lower PPVs. Thus, women who are screened with MRI have more negative surgical biopsies.
Because all studies of MRI screening are observational, none can assess morbidity, survival, or mortality, compared with other screening modalities, though it is likely that MRI screening results in overdiagnosis (refer to the Overdiagnosis section in the Harms of Screening Mammography section of this summary for more information).