Abstract P5-01-12: Breast specific gamma imaging (BSGI) and breast magnetic resonance imaging (MRI): Comparison of sensitivity and specificity in women prior to breast biopsy with BIRADS 4 or 5 finding on mammography in a community setting

Background : Diagnostic imaging following a new diagnosis of breast cancer remains an active area of research balancing value and outcomes. Decisions about surgical options and neo-adjuvant therapy depend greatly on the accuracy of these pre-operative assessments. BMRI use has increased tenfold from 2000 to 2011 (Stout et al, JAMA 2013) and estimation of sensitivity has been high but specificity has varied between 30-80%(Bluemke et al, JAMA 2004). BSGI is a novel molecular imaging technique that uses a gamma camera to track the uptake of a radio tracer (technitium Tc99m sestamibi) by breast cancer cells and has been used interchangeably with BMRI without rigorous evidence of equivalency (Khalkhauli, et al, J Nuc Med 2000).The majority of research into the sensitivity and specificity of these tests has been retrospective, only on women with known cancer, and potentially biased by post-biopsy changes to breast tissue. Methods : Therefore we performed a prospective study employing both techniques to image women with BIRADS 4 or 5 lesions on diagnostic mammogram prior to their planned breast biopsy. The BSGI and BMRI were reviewed by one of three dedicated breast radiologists and the pathology was reviewed on the biopsy or any additional biopsy/excision by one pathologist. We compared the BSGI and BMRI against the final pathology for sensitivity and specificity. In addition, we surveyed the women for quality of life measures 3 months later. Results : Between January 2012 and April 2014 we enrolled 74 women (ages 30-80) at 2 NAPBC accredited breast centers located in a community based setting in Portland, OR. The initial diagnostic mammographic studies resulted in 23 women (32%) with BIRADS 4A, 27 (37%) with BIRADS 4B, 8 women with 4C (11%) while 8 women (11%) had BIRADS 5 lesions prompting biopsy. All women were biopsied and 27 (37%) were found to have an invasive or in situ cancer while 5 (7%) had atypical hyperplasia or LCIS found. Sixteen women had additional biopsies performed, outside of the planned area, as a result of BMRI or BSGI, 11 (69%) were based on BMRI findings and 5 (31%) were areas seen on both BMRI and BSGI. In these additional biopsies 5 were in situ or invasive cancer and 2 were contra-lateral cancers, the rest were benign tissue. The sensitivity of BMRI was 84.0% and BSGI was 74.1%. The specificity was found to be 57.8% and 80.4% respectively. One patient withdrew and 3 women did not complete BMRI due to claustrophobia or body habitus. Quality of life data is still being analyzed. Conclusions : We report here the sensitivity and specificity of BMRI compared with BSGI in women with BIRADS 4 and 5 breast lesions on diagnostic mammography. Importantly imaging was done before biopsy and therefore not biased by any effect from that procedure. In this study we find BMRI appears to have better sensitivity but lower specificity than BSGI. We also observed that the use of BMRI and/or BSGI prompted 16 extra biopsies of which less than half were additional or contra-lateral cancer. The incorporation of these tests into the evaluation of suspected cancer should consider these findings as well as cost and quality of life. Citation Format: Alison K Conlin, Nicole Moxon, Helena Hoen, Christina Gougoutas-Fox, Maureen O Baxter, Amy Weinstein, Maritza Martel, Tracy L Kelly, Walter J Urba. Breast specific gamma imaging (BSGI) and breast magnetic resonance imaging (MRI): Comparison of sensitivity and specificity in women prior to breast biopsy with BIRADS 4 or 5 finding on mammography in a community setting [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-01-12.