Abstract P4-02-05: Predictors of MRI detection of occult lesions in newly diagnosed breast cancer

BACKGROUND: The appropriate use of preoperative magnetic resonance imaging (MRI) in patients with newly diagnosed breast cancer remains a topic of debate. We aimed to determine the usefulness of MRI in the detection of occult multicentric, multifocal and contralateral lesions not seen by ultrasound or mammography. METHODS: We performed a retrospective analysis of consecutive patients who underwent preoperative MRI for newly diagnosed biopsy-proven stage 0-III breast cancer who were treated surgically from January 2006-March 2013. All newly diagnosed breast cancer patients at our two affiliated institutions were evaluated with pre-operative MRI. Patients who received neoadjuvant systemic therapy or surgery at an outside institution were excluded from our study. Demographic, radiographic and pathologic data points including age, race, body mass index (BMI), lesion size, mammographic density, biopsy histology, and biomarkers were assessed for each patient with respect to the findings of multifocality, multicentricity, and the presence of contralateral lesions on all three imaging modalities. We performed univariate analysis associating factors separately in each of three models with multicentric, multifocal and contralateral disease on surgical pathology followed by multivariable analysis using logistic regression to calculate odds ratios. RESULTS: Of 857 patients undergoing breast MRI within this time period, 770 patients were identified who met inclusion criteria. All patients underwent diagnostic mammogram and ultrasound followed by MRI. The patient population was 44.2% Hispanic, reflective of the population of our two institutions. Mean age was 54.7 years. MRI identified 86 patients with biopsy-proven multicentricity compared to 66 on conventional imaging. MRI identified 170 patients with biopsy-proven multifocality compared to 132 on conventional imaging. Finally, MRI identified 24 patients with biopsy-proven contralateral cancers compared to 7 on conventional imaging. Biopsy histology of invasive lobular carcinoma was predictive of the presence of multifocality on MRI (p=0.038, OR=1.95, 95% CI 1.09-3.48). Mammographic density was found to be a predictor of multicentricity (p=0.015, OR=2.22, 95% CI 1.13-3.33). Lesion size trended towards statistical significance on multivariate analysis of the multicentric lesions (p=0.057, OR=1.88, 95% CI 1.00-3.51). For contralateral cancers seen on MRI the presence of invasive lobular carcinoma on biopsy (p=0.027, OR=4.83, 95% CI 1.25-16.21) was predictive of finding a contralateral cancer. CONCLUSIONS: Predictive factors including breast density, biopsy histology, and lesion size should be taken into account as clinical predictors of utility of pre-operative breast MRI. This data is being used to construct nomograms to predict multicentric, multifocal and contralateral disease to aid clinicians in evaluating the potential clinical utility of preoperative breast MRI. Citation Format: Wecsler JS, Raghavendra A, Mack WJ, Tripathy D, Yamashita M, Sheth P, Hovanessian-Larsen L, Sener SF, Russell CA, MacDonald H, Lang JE. Predictors of MRI detection of occult lesions in newly diagnosed breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-02-05.