Abstract P1-03-06: Risk stratification by ultrasound for screen-detected non-palpable breast cancer in Chinese women: Regular low risk versus ultra-low risk?
Authors: Xu Y , Pan B , Yao R , Zhou Y-d , Mao F , Zhu Q-L , Zhang J , Lin Y , Shen S-j , Sun Q 
Published: May 2019

Background: Mammography (MG) screen-detected breast cancer has been established as low-risk in the western world. However, ultrasound (US) is currently the 'real-world' initial imaging test for breast cancer in China. In our previous work, we firstly showed with a multi-center randomized controlled trial that US could detect breast cancer with improved sensitivity and accuracy in high risk Chinese women [PMID: 25668012]. Then we demonstrated on a hospital-screening basis that US and MG detected non-palpable breast cancer (NPBC) had similar survival [2016 SABCS P5-02-05, PMID: 27689334]. This study was performed to test the hypothesis [Hypothesis would be published in the journal of Medical Hypothesis, 118 (2018):9-12] whether MG+/US- NPBC could be taken as ultra-low risk cancer which had more favorable clinical characteristics and survival than the regular low-risk NPBC.

Methods: From 2015-2017, 1,478 consecutive patients received biopsy with initial positive screening US (BI-RADS 4 and 5) at Peking Union Medical College Hospital. Among them, 206 US+/MG- and 135 US+/MG+ NPBC were diagnosed. Meanwhile, 371 patients who had negative initial screening US (BI-RADS 1, 2 and 3) and positive additional MG (BI-RADS 4 and 5) underwent MG-guided biopsies, and 88 MG+/US- NPBC were diagnosed. Clinical characteristics, treatment and 3-year disease free survival (DFS) and overall survival (OS) were analyzed and compared. Prognostic factors were identified.

Results: There was no significant difference in age, lymph node status, hormone receptor status, endocrine therapy, chemotherapy, targeted-therapy among the three subgroups of NPBC. MG detected significantly more ductal carcinoma in situ (DCIS, 59.1% vs 22.8% and 28.1%, p&lt;0.001) whereas ultrasound diagnosed more invasive cancers (77.2% and 71.9% vs 40.9%, p&lt;0.001), multifocal cancer (p=0.020) and patients who received breast-conserving surgery (p&lt;0.001) and needed radiotherapy (P=0.001). No significant difference was found for 3-year DFS and 3-year OS were all 100%, although MG+/US- NPBC showed a trend of better DFS.

Table 1.Comparison of positive predictive value (PPV), pathology and prognosis of US+/MG-, US+/MG+ and MG+/US- NPBCPathologyRadiology (2015-2017)US-detected NPBL (N=1,478)US-detected NPBL(N=1,478)MG-detected NPBL (N=371)MG & US positivityUS+/MG- (N=1,108)US+/MG+ (N=370)MG+/US- (N=371)Imaging presentationNoduleNodule + micro-calcificationsMicro-calcificationsBreast cancer (PPV %)206 (18.6%)135 (36.5%)88 (23.7%)Pathology (p&lt;0.001)   DCIS (%)47 (22.8)38 (28.1)52 (59.1)Invasive (%)159 (77.2)97 (71.9)36 (40.9)3-Year survival   DFS (%)92.391.196.5OS (%)100.0100.0100.0

Conclusion: MG+/US- NPBC had satisfactory prognosis, higher percentage of DCIS and might be taken as 'ultra-low risk' cancer. Hence US had the potential of stratifying the screen-detected NPBC into regular low risk (US+/MG+ and US+/MG-) and ultra-low risk (MG+/US-).

Citation Format: Xu Y, Pan B, Yao R, Zhou Y-d, Mao F, Zhu Q-L, Zhang J, Lin Y, Shen S-j, Sun Q. Risk stratification by ultrasound for screen-detected non-palpable breast cancer in Chinese women: Regular low risk versus ultra-low risk? [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-03-06.