The purpose of this study is to evaluate the role of technologist-performed whole breast ultrasound for detecting breast cancer in the screening population of women with dense breasts.

This is a prospective study designed to evaluate the role of whole breast ultrasound (WBUS) in screening for breast cancer. In particular, there is interest in investigating the value of using WBUS as an adjunct (supplementary imaging) to Digital Breast Tomosynthesis (DBT) based screening of women with dense (heterogeneously or extremely dense) breasts or as a primary screening examination in this group of women. Women scheduled for their routine mammography that includes a DBT exam who agree to participate in the study and sign informed consent will undergo (at the same visit) DBT imaging as part of their clinical exam and whole breast ultrasound (WBUS) each year for three rounds of screening plus one year of follow-up. The DBT images and WBUS will be interpreted independently by two experienced radiologists under standard clinical screening procedures. One radiologist will interpret the DBT and the other radiologist will interpret the WBUS. Using a modified "LOGICAL OR" approach women/subjects may be recalled for further diagnostic work-up (examinations). If a subject is recalled, she will then follow the standard/routine clinical procedures for follow-up and the investigators will verify outcomes. If neither radiologist recalls the subject, then the subject will follow conventional management and the investigators will verify outcome. The findings from the DBT and WBUS examinations, as well as any resulting follow-up, will be collected, recorded and analyzed.

Inclusion Criteria:

• Women aged 40 to 75 years of age with heterogeneously dense or extremely dense parenchyma by prior digital mammography report (i.e., "dense breasts"), presenting for routine annual mammography with digital breast tomosynthesis.

Exclusion Criteria:

• Known to be at high risk for breast cancer due to known or suspected pathologic BRCA mutation (i.e. first-degree relative with known mutation) or prior chest radiation therapy before age 30;
• No mammogram within the prior 3 years;
• Signs or symptoms of breast disease including lump, bloody or spontaneous clear nipple discharge, eczema of the nipple;
• Pregnancy or lactation within the prior 6 months;
• Plan to become pregnant in the next two years, as mammography is not typically performed for screening pregnant women;
• Breast implants, as assessment of breast density may be problematic;
• Recent prior breast surgery or breast biopsy or cyst aspiration within the prior 12 months;
• Prior or current malignancy other than the following: a) Breast cancer at least one year earlier (12 full months have elapsed since the last treatment surgery) with no known distant metastases and no known residual tumor; or b) Basal or squamous cell skin cancer or in situ cervical cancer or stage I thyroid cancer; or c) Other cancer for which the patient has been disease free for ≥ 5 years, with no recurrence of cancer in the last five years and no residual disease detected in the last five years.
• Screening contrast-enhanced MRI or 99mTc-sestamibi based imaging of the breast(s) within the prior 12 months or planned within the next two years, to avoid contamination of results;
• Unwilling or unable to provide consent.

After exclusions, we analyzed the results from 6,179 women overall

3 years