Evaluation of the Effect of Using Ultrasound Robots for Breast Cancer Screening: A Multicenter, Parallel-group, Cluster Randomized Controlled Trial

Number of detected ductal carcinoma in situ (DCIS) and invasive breast cancers divided by the total number of screened participants.

Non-invasive cancer (DCIS), early invasive cancer, and invasive cancer.

The early diagnosis rate is defined as the number of breast cancer cases with TNM stage 0, I, or IIa divided by the number of women diagnosed with breast cancer or other malignant breast tumors during screening*100.

Presence of lymph node metastasis; size, morphology, internal structure, margin characteristics, and vascularity of metastatic lymph nodes.

TNM staging, representing tumor size (T), lymph node involvement (N), and distant metastasis (M).

The internationally accepted Nottingham Histological Grading System is used. This system provides a semi-quantitative and objective assessment of invasive breast cancer. It evaluates three parameters: the proportion of tubule formation, nuclear pleomorphism, and mitotic count. The scores of the three parameters are added together. A total score of 3-5 indicates Grade 1 (G1, well-differentiated/low grade). A total score of 6-7 indicates Grade 2 (G2, moderately differentiated/intermediate grade). A total score of 8-9 indicates Grade 3 (G3, poorly differentiated/high grade).

Breast cancer screen recall is defined as further assessment triggered by abnormal ultrasound findings (BI-RADS 0 or 3 and above). The recall rate is the number of women actually recalled divided by the number of women screened.

The positive predictive value of recall is the percentage of recalled women who are diagnosed with breast cancer.

The breast cancer biopsy rate is defined as the number of women who actually underwent biopsy divided by the number of women screened. The positive predictive value of biopsy is defined as the percentage of women diagnosed with breast cancer among those who received a biopsy.

Defined as the average adherence to recommended referral for confirmed diagnosis (biopsy and histopathology). It is calculated as the number of women actually referred divided by the number of women recommended for referral.

Defined as the proportion of women who had a negative or false-positive screening (i.e., no ductal carcinoma in situ or invasive breast cancer) and were subsequently diagnosed with invasive breast cancer within a certain period after screening. Following the national breast cancer screening guideline recommending screening every 2-3 years, this study will evaluate the interval cancer incidence at 24 months, i.e., the proportion of women diagnosed with breast cancer 24 months after a negative screen or 6-24 months after a false-positive screen.

Defined as the number of deaths due to breast cancer within 24 months after screening divided by the total number of women screened.

Defined as the total number of deaths from any cause within 24 months after screening divided by the total number of women screened.

Defined as the proportion of women who completed the recommended follow-up medical actions after screening (referral, re-examination, additional tests, etc.). The adherence rate is calculated as the number of participants who completed the recommended management within the specified time / the number of participants requiring further management * 100%.