Objective: Mammographically dense breast tissue has been reported both as a cause of false-negative findings on mammography and as an indicator of increased breast cancer risk. We conducted this study to evaluate the role of breast sonography as a second-line screening test in women with mammographically dense breast tissue.
Materials and methods: Between January 2000 and January 2002, 1517 asymptomatic women with dense breasts and normal mammography and physical examination findings underwent physician-performed breast sonography as an adjunct screening test. Within the study group, 318 women had a first-degree family history or personal history of breast cancer. The high-risk subgroup comprised these women. The detection rate of breast cancer in this subgroup was compared with the detection rate in the remaining study population with baseline risk.
Results: Of 1517 women examined, seven breast cancers were diagnosed (cancer-detection rate, 0.46%). Four carcinomas were detected in high-risk women and three in women with baseline risk. The cancer-detection rate in the subgroup of high-risk women was 1.3%, significantly higher (p < 0.04) than the cancer-detection rate of 0.25% in the baseline risk subgroup. All cancers were T1 (range, 4-12 mm; mean, 9.6 mm). Sentinel lymph nodes were negative for cancer in six of seven carcinomas.
Conclusion: Screening breast sonography in the population of women with dense breast tissue is useful in detecting small breast cancers that are not detected on mammography or clinical breast examination. The use of sonography as an adjunct to screening mammography in women with increased risk of breast cancer and dense breasts may be especially beneficial.