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Scientific Session 17 — Breast -MRI/New Technologies

Wednesday, May 3, 2017

Abstracts 1031-2861



1031. Assessing the Response of Benign Breast Lesion to Neoadjuvant Chemotherapy in Comparison to Cancers

Leddy R*,  Irshad A,  Hewett L,  Vento F,  Lewis M. Medical University of South Carolina, Charleston, SC

Address correspondence to R. Leddy (leddyr@musc.edu)

Objective: Our aim was to determine the effects of neoadjuvant chemotherapy on benign breast lesions and to evaluate their response in comparison with the response of cancers, which may help make appropriate management decisions.

Materials and Methods: After institutional review board approval, a retrospective analysis on our breast imaging database between August 2008 and June 2014 was performed to identify patients with previously diagnosed breast cancer who received neoadjuvant chemotherapy and underwent MRI both before and after therapy. Among these 113 patients, 38 were identified who also had a biopsy-proven benign breast lesion for a total of 47 lesions. Both the cancer and the benign lesion in each patient were evaluated for size (in centimeters) and intensity of enhancement (graded 1–4; minimal, mild, moderate, and marked) on the pre- and posttherapy MRI. Overall breast glandularity and background enhancement were categorized according to BI-RADS (graded as 1–4 for analysis). The statistical analysis was performed as follows: For change in size and enhancement of cancers and benign masses, a 2 (intervention before and after) × 2 (cancerous or benign tumor) repeated measures ANOVA was conducted. Post hoc tests were conducted using the Sidak method for multiple comparisons. For analyzing change in glandularity and background enhancement, a repeated measures t test was conducted to examine changes over time and two-tailed p values were reported. All analyses were considered significant at the p < 0.05 threshold.

Results: Pre- and posttherapy MRI showed that neoadjuvant therapy affected the size of benign lesions and cancers differently (F [1, 46] = 42.36, p < 0.001). Both the cancerous and benign tumors showed a significant size reduction after therapy, but the change in size was more dramatic for the cancerous tumors. The mean size ± SD on pre- and posttherapy MRI for cancers versus benign lesions were 4.09 ± 2.51 cm and 1.54 ± 2.32 cm (p < 0.001) versus 0.83 ± 0.54 cm and 0.28 ± 0.51 cm (p < 0.001). For both benign lesions and cancers, there was a significant reduction in enhancement from a moderate value before therapy (mean, 3.191 ± 0.10) to a minimal value after therapy (mean, 1.00 ± 0.14; F [1, 46] = 184.50, p < 0.001). There was no overall difference in enhancement for the cancers (mean, 2.22 ± 0.79) versus benign lesions (mean, 1.97 ± 1.08; p = 0.23). There was no change in glandularity before (mean, 3.11 ± 0.84) and after (mean, 3.13 ± 0.82) therapy (t [46] = 0.44, p = 0.66); however, there was a significant decrease in background enhancement before (mean, 2.38 ± 0.97) and after (mean, 1.64 ± 0.70) therapy (t [46] = 4.95, p < 0.001).

Conclusion: Benign breast lesions show significant decrease in size and enhancement after neoadjuvant chemotherapy; however, the decrease in size is less than the cancers. Any additional ipsilateral or contralateral lesions seen on preoperative MRI that respond to neoadjuvant chemotherapy similar to the patient’s known cancer may be benign and not be presumed to be cancers. Management decisions should still rely on the initial level of suspicion.