Neoadjuvant chemotherapy versus adjuvant chemotherapy in breast cancer patients: Analysis of breast conserving rate and de-escalation of axillary surgery in 5,141 Korean women.

Abstract

e12531 Background: Neoadjuvant chemotherapy (NCT) in breast cancer has several advantages such as more breast conservation surgery (BCS) rate and de-escalation of extent of axillary surgery. Actual practice change in this area compared with adjuvant chemotherapy (ACT) is not well established. Methods: We retrospectively analyzed 5,141 women diagnosed with breast cancer from 2009 to 2013, treated with chemotherapy before or after definite surgery. BCS rate and axillary surgery categories (sentinel lymph node biopsy (SNB), axillary lymphnode dissection (ALND) or SNB followed by ALND) are compared between two groups. Results: Among 5,141 patients, 3930 (76.4%) women had ACT and 1211 (23.6%) had NCT. Median age at diagnosis was 48 (range 22-83). BCR rate was lower in T2 (57.1% vs 64.1%), T3 (12.6% vs 20.9%) group between ACT vs NCT ( p=0.03, 0.001), no difference was shown in T1 and T4 tumors. SNB try (SNB only or SNB followed by ALND) rate was still higher in ACT group with cN0 (98.4% vs 95.4%), cN1 (89.3% vs 73.5%), cN2 (77.9% vs 62.1%) tumors ( p=0.001, <0.001, 0.003, respectively). SNB only rate which means that patients spared ALND, was lower in ACT group with all cN stage (cN1; 17.5% vs 29.2%, cN2; 3.2% vs 5.9%, cN3; 5.1% vs 20.5%, all p=0.000) except cN0 (95.6% vs 81.4%, p<0.001). Axillary surgery rate analyzed with pathologic N stage showed more ALNDs attempted even after achieving pathologic complete nodal response or minimal residual N disease (ypN0: 4.4% vs 27.2%, ypN0(i) & ypN1mi; 26.2% vs 57.6%, p<0.001, =0.001 respectively). In contrast however, average of total axillary nodes retrieved by cN stage were statistically lower in NCT group in clinically positive tumors (N1; 15.3 vs 12.7, N2; 19.1 vs 14.6, N3; 25.1 vs 15.6, all p<0.001). Conclusions: NCT had shown advantage to perform more BCS than ACT in T2, T3 tumors. SNB attempts in NCT was comparable to ACT. Still, patients with NCT received more aggressive axillary surgery than ACT shown by axillary surgery category irrespective of negative SNB results.