Abstract P3-01-03: The loss of lymph node metastasis after neoadjuvant chemotherapy in patients with cytologically proven node-positive primary breast cancer

Abstract

Abstract Purpose:While the sensitivity to neoadjuvant chemotherapy (NAC) depends on breast cancer subtype, it has been reported that over 30% of patients with node-positive breast cancer achieved an axillary pathologic complete response (pCR) after NAC. However, axillary lymph node dissection (ALND) still remains as a standard treatment because of the difficulty of assessment of lymph node (LN) status after NAC. ALND will be omitted if axillary LN status is accurately assessed. Our purpose of this study was to predict the loss of axillary LN metastasis after NAC in primary breast cancer patients. Patients and Methods: Among 997 consecutive patients who underwent surgery after NAC from January 2006, to December 2016, 279 patients with cytologically proven node-positive were included in this analysis. All patients were assessed using CT or PET-CT, and ultrasonography (US) before NAC. LN status after NAC was assessed by US. Patients with cT4 tumor, and supra/subclavicular and parasternal LN metastasis were excluded. Clinical LN status after NAC (ycN) was compared to pathological LN status (ypN) on surgical specimen. The association between LN status and clinicopathological factors including nuclear grade (NG), tumor size, the use of trastuzumab, and breast cancer subtypes, was assessed. Result: Of the 279 patients with LN-positive before NAC, 166 patients (59.5%) had ER+/HER2- tumor, 51 patients (18.3%) had ER+/HER2+ tumor, 33 patients (11.8%) had ER-/HER2- tumor, and 29 patients (10.4%) had ER-/HER2+ tumor. 179 patients (64.2%) had ycN0 and 102 patients (36.6%)had ypN0. There was significant difference of rate of the loss of LN metastasis after NAC; 37 of 166 patients (22.3%) with ER+/HER2- tumor, 24 of 51 patients (47.1%) with ER+HER2+ tumor, 19 of 33 patients (57.6%) with ER-HER2- tumor, and 22 of 29 patients (75.9%) with ER-HER2+ tumor, (p<0.01).The accuracy of assessment of the loss of LN metastasis by US (ycN0/ypN0) was high in 20 of 25 patients (80.0%) with ER-/HER2+ tumor and in 14 of 19 patients (73.4%) ER-/HER2- tumor compared to ER+ tumor; 21 of 39 patients (53.8%) with ER+/HER2+ tumor and 34 of 96 patients (35.4%) with ER+/HER2- tumor (p<0.01). For patients with ycN0/ypN+, the median number of residual LN metastasis was 1 in ER-/HER2+ tumor (range:1-2) and ER-/HER2- tumor (range:1-3), and 2 in ER+/HER2+ tumor (range:1-6) and ER+/HER2- tumor (range:1-14). Among patients with ER-/HER2+ tumor, there was association between the loss of LN metastasis and the use of trastuzumab (p<0.01). There was no association between the loss of LN metastasis and NG or tumor size. Conclusion: Our results showed patients with ER-/HER2+ tumor and cytologically proven LN metastasis who received NAC with trastuzumab might have the loss of LN metastasis if assessed as ycN0 by US after NAC, whereas, the patients in ER+ tumor have a high risk to have residual LN metastases after NAC even if assessed as ycN0. Further studies are warranted the prognostic impact of the omission of ALND for these populations. Citation Format: Namura M, Hayashi N, Tsunoda H, Yoshida A, Takei J, Suzuki K, Nakamura S, Yamauchi H. The loss of lymph node metastasis after neoadjuvant chemotherapy in patients with cytologically proven node-positive primary breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-01-03.