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Use of magnetic resonance imaging to plan breast conserving surgery following neoadjuvant chemotherapy for early breast cancer.

658 Background: The selection of patients (pts) for breast conserving surgery (BCS) following neoadjuvant chemotherapy (NAC) is dependant upon accurate assessment of the extent of residual disease within the breast such that up to 60 % patients fail primary surgery and require re-excision or mastectomy.


METHODS
All pts seen over a 3-year period with histologically confirmed invasive breast cancer on core biopsy, stage cT2 -T3, who were not suitable for, but desired BCS, were considered for NAC. T4 tumours were excluded. Pre and post NAC mammography (MM), breast ultrasound (U/S), and MRI were independently reported and compared with clinical and pathological assessment and whether BCS achieved by segmental mastectomy and sentinel node guided axillary sampling.


RESULTS
32 pts median age 42 years (range 24-60) were treated; 22 (69%) pre-menopausal; stage I (6%), II (62%), III (31%) Median tumour size pre-NAC was 4.75cm (range 2-8cm) on physical examination. All received 6 cycles of anthracycline based chemotherapy. Clinical response: CR 12.5%, PR 81.3% SD 6.2%. MM in this young population was uninformative in 62.5% following NAC. U/S and MRI correlation with pathological response was r= 0.65 and r=0.71 respectively. In 4 pts, MRI tumour size was > 1cm larger than pathological size because of associated DCIS in 3 and post treatment hyaline fibrosis in 1 patient. In 2 pts, MRI size was > 1cm smaller because of delayed surgery. MRI but not U/S was able to differentiate between residual invasive tumour and DCIS or fibrosis from the gadolinium enhancement curves. Following NAC 25 (72%) were suitable for BCS (unsuitable- proximity to nipple 5, multifocal 1, skin tethered 1) of whom 20 proceeded (3 chose mastectomy, 2 radiotherapy only). 17 (85%) pts had successful initial surgery, 3 (15%)had positive margins requiring re-operation because of difficulty locating very small residual masses.


CONCLUSIONS
MRI aided the selection of pts for BCS after NAC due to the high correlation with pathological findings. 72% pts achieved BCS, 85% of them with single operation. No significant financial relationships to disclose.