Agreement between digital breast tomosynthesis and pathologic tumour size for staging breast cancer, and comparison with standard mammography. (February 2019)

• Record Type: Journal Article
• Authors: Marinovich, M. Luke; Bernardi, Daniela; Macaskill, Petra; Ventriglia, Anna; Sabatino, Vincenzo; Houssami, Nehmat
• Is Part Of: Breast. Volume 43(2019)
• Page Start: 59
• Page End: 66
• Publication Date: 2019-02
• Subjects: Tomosynthesis -- Mammography -- Breast cancer -- Staging -- Tumour size -- Accuracy; Breast -- Diseases -- Periodicals; Breast -- Tumors -- Periodicals; Breast -- Periodicals; Electronic journals; Periodicals; 616
• DOI: 10.1016/j.breast.2018.11.001
• Languages: English
• ISSNs: 0960-9776

Abstract

Abstract: Purpose: Tomosynthesis is proposed to improve breast cancer assessment and staging. We compared tomosynthesis and mammography in estimating the size of newly-diagnosed breast cancers. Methods: All pathologically-confirmed cancers detected in the STORM-2 trial (90 cancers, 85 women) were retrospectively measured on tomosynthesis by two independent readers. One reader also measured cancers on mammography. Relative mean differences (MDs) and 95% limits of agreement (LOA) with pathology were estimated for tomosynthesis and mammography within a single reader (Analysis 1) and between two readers (Analysis 2). Results: Where cancers were detected and hence measured by both tests, tomosynthesis overestimated pathologic size relative to mammography (Analysis 1: MD 5% versus 1%, Analysis 2: 7% versus 3%; P = 0.10 both analyses). There was similar, large measurement variability for both tests (LOA range: −60% to +166%). Overestimation by tomosynthesis was attributable to the subgroup with dense breasts (MDs = 12–13% versus 4% for mammography). There was low average bias for both tests in the low-density subgroup (MDs = 0–4%). LOA were larger in dense breasts for both tomosynthesis and mammography ( P ≤ 0.02 all comparisons). Cancers detected only by tomosynthesis were more frequently in dense breasts (60–68%): for those tumours size was estimated with increased measurement variability (LOA ranging from −75% to +293%). Conclusions: On average, tomosynthesis overestimates pathologic tumour size in women with dense breasts; that difference is more likely to impact management in women with larger tumours. The main advantage of tomosynthesis appears to be detecting mammographically-occult cancers; however tomosynthesis less accurately measured those cancers in dense breasts (large measurement variability). Highlights: Tumour size was overestimated by tomosynthesis relative to mammography. Overestimation was attributable to the subgroup with high breast density. There was low average bias for both tests in the low-density subgroup. Cancers detected only by tomosynthesis were measured with large variability.