Is breast magnetic resonance imaging (MRI) useful for diagnosis of additional sites of disease in patients recently diagnosed with pure ductal carcinoma in situ (DCIS)?

Purpose: To determine if breast MRI is useful for detecting additional or invasive sites of disease in patients initially diagnosed with pure DCIS. Materials and methods: A retrospective review of women diagnosed with pure DCIS who underwent a breast MRI for evaluation of extent of disease was performed at a single institution from January 2013 to April 2015. Data analysis included imaging (mammography, ultrasound and MRI) and pathology characteristics (histology and biomarker status) of the primary DCIS as well as descriptors for the additional sites of disease incidentally found by breast MRI. Results: A total of 108 patients were diagnosed with pure DCIS during this time period. A breast MRI for staging was recommended for all patients. 76 patients had an MRI performed, ages ranging from 38 to 79 years old (median, 53 years); sizes ranging from 0.3 to 10 cm (mean, 2.2 cm). A total of 52 patients (68%) either had suspicious new finding(s) (n = 27, 36%) or bigger tumor size than originally visualized on mammography (n = 43, 57%). A total of twenty-seven patients (36%) had other MRI findings suspicious for additional sites of disease in either breast (four in the ipsilateral breast and twenty-three in the contralateral breast). From this group of patients, twenty-three (85%) patients underwent MRI-guided biopsy as recommended. The four patients who did not have the recommended MRI guided-biopsy either underwent total mastectomies or refused the biopsy. Six out of the twenty-three patients (26%) were diagnosed with an additional site of cancer (5 DCIS and 1 IDC) (7.9%, CI = 3.7%, 16.2%). All of the six patients had contralateral disease (100%) and none had a second site of disease in the ipsilateral breast. The size of the additional sites of disease ranged from 0.4 to 8 cm (mean, 3.1 cm) and the size of the primary lesion in this selected group ranged from 0.1 to 10.9 cm (mean, 5.6 cm). Ages ranged from 44 to 63 years old (median, 52.5 years). Five out 6 patients (83%) presented with the first site of disease as pure DCIS with estrogen (ER) and progesterone (PR) receptors positive and one case (17%) was pure DCIS ER/PR- negative. The second incidental lesion found on MRI demonstrated 5 cases of contralateral pure DCIS and 1 case of contralateral invasive disease. From this group, we did not have the data for biomarker analysis for the second site of disease in 2 cases and 3 cases showed concordant biomarker status between the first and second sites of disease. The 1 case that presented with an invasive component in the contralateral side of the initially biopsy-proven pure DCIS had discordant biomarkers compared to the first site of disease: the first site of pure DCIS was ER/PR-negative and the second site of invasive ductal carcinoma (IDC) presented with ER/PR-positive status. Conclusion: From a total of 76 patients with recent diagnosis of pure DCIS who underwent staging breast MRI examination for diagnosis of additional sites of disease, approximately 8% (95% confidence interval = 3.7%, 16.2%) was diagnosed with an additional site of cancer and 1.3% (95% confidence interval = 0.2%, 7%) of the total cases had invasive disease in the additional sites with different biomarker status; changing their management and prognosis.