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Breast cancer surveillance in high-risk women with magnetic resonance imaging every 6 months.
Abstracts that were granted an exception in accordance with ASCO's Conflict of Interest Policy are designated with a caret symbol (^).
Background: Surveillance with mammography (MMG) and magnetic resonance imaging (MRI) is recommended for women at high-risk for breast cancer, but there is no consensus on screening strategy. Aim of this study was to evaluate the efficacy of semi-annual MRI in high-risk women. Methods: A multi-modality surveillance program was initiated in 2004. Yearly MMG was supplemented with semi-annual MRI. After 5 years, an additional 5 years of follow-up with yearly MMG and MRI was offered to mutation carriers. Defining positive screening as BIRADS 0, 4 and 5, sensitivity, specificity, NPV, and PPV of semi-annual MRI were analyzed. Results: From 2004 to 2012, 226 patients underwent 1467 MRI and 851 MMG with a mean follow-up of 3.6 yrs. Median age at entry was 43 yrs (range 21-73), 48% were mutation carriers (105 BRCA1/2, 2 CDH1, 1 P53) and 19% had personal history of breast cancer. Eleven cancers were screen-detected, of which 6 (55%) were detected only by MRI, 1 (9%) only by MMG, and 4 (36%) by both. Of these tumors, 4 were detected in the first round of MMG/MRI screening and 7 (64%) in mutation carriers (5 BRCA1, 1 BRCA2, 1 CDH1), and 3 tumors (27%) were detected due to the additional MRI during semi-annual screening. No interval cancers occurred. Sensitivity, specificity, PPV and NPV of MRI were 91%, 97%, 18%, 99%, respectively. Of the incident cancers, 3 (27%) were stage 0 (ductal) and 8 (73%) were stage 1 (7 ductal and 1 lobular). Mean size of the invasive cancers was 0.78 cm (range 0.1-1.6; only 2 tumors > 1.0 cm), none had lymph node metastasis, and 75% were high grade and hormone receptor positive. The largest tumor detected was invasive lobular in a 73 year old CDH1mutation carrier. Conclusions: To our knowledge, this is the first surveillance protocol with repeated screening rounds that detected mean size of invasive tumors less than 1 cm. Absence of interval cancers, high sensitivity/specificity, and detection of all tumors in early stages (stages 0 or 1) support this screening strategy as a viable alternative to prophylactic mastectomy. Ongoing work will examine quality of life, cost effectiveness and impact on overall survival of this screening approach. Clinical trial information: NCT00989638.