Core Biopsy Following Neoadjuvant Chemotherapy Predicts Tumour Response and Aids in Breast Preservation.

Abstract Back groundAdvancement in chemotherapy regimens has improved pathological tumour response following neoadjuvant chemotherapy (NAC). This has subsequently helped in increasing incidence of breast preservation. Here we report how core biopsy of the tumour bed following NAC is useful in predicting tumour response and aids in breast preservation.Materials and MethodsData were collected retrospectively from consecutive newly diagnosed breast cancer patients at West Middlesex University Hospital between January 2002 and December 2008 who underwent NAC. Patients were assessed with clinical examination, mammogram, ultrasound (USS) and Magnetic Resonance Imaging (MRI). NAC consisted of 6-8 cycles of FEC or had FEC followed by Taxanes. The tumour response was assessed by USS and MRI. In addition, multiple cores were performed both in the central and periphery of the tumour bed. Patients subsequently underwent either mastectomy or wide local Excision (WLE) with axillary clearance. The extent of resection was determined by the presence of tumour in the peripheries.Results43 patients received neo-adjuvant chemotherapy and the median age was 49 years (range 24-72). The median size of tumour by MRI scan was 4.5 cm (range 2.5-10). One patient declined surgery and 8 patients did not have core biopsy following neoadjuvant chemotherapy so all the nine cases were excluded from analysis.The sensitivity of USS, MRI and core biopsy in predicting residual disease in our series was 84%, 84% and 68% respectively. The specificity and the positive predictive value (PPV) of imaging was 25% and 75% whereas the specificity and PPV of core biopsy was both 100%.Our overall initial breast conservation rate was 88% (30 of 34) and 4 of them had subsequent mastectomy following breast conservation surgery (BCS) due to positive margins following BCS reducing it to 76% (26/34).The mean size of the T2 tumour was 2.9 cm and 90% had BCS (9/10) including re excision of margins in one case. The average size of the T3 tumour was 6.0 cm and 76% (13/17) had BCS. Re excision of positive margins was done twice in one case. The mean size of T4 tumour in our series was 6.3 cm and 57% had BCS (4/7).DiscussionThe tumour response following NAC is traditionally assessed by imaging and further surgery is determined by the extent of response. The low specificity and PPV of imaging is due to overestimation of the presence of residual tumour. Absence of enhancement in MRI means either there is necrosis or fragmentation. This is especially true when the tumour mass has completely resolved. The presence of architectural distortion in these cases can complicate MRI interpretation. It is interesting to note that MRI has a high negative predictive value in diagnosing primary tumour as well as recurrence. However this ability is lost following chemotherapy for above mentioned reasons. So core biopsy is an extremely useful tool here when it is positive irrespective of what the imaging indicates. The rate of breast conservation is also increased by assessing tumour response to decide the extent of resection. Extensive sampling of the central and periphery of the tumour following chemotherapy increases the negative surgical margins when breast conservation is considered. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4121.