Positive margins, fibroproliferation in the surrounding breast tissue, and necrosis are associated with a marked increase in LR rates. Efforts should be made to achieve negative surgical margins to reduce risk of LR. Death from PT is rare (2%), and only PT that demonstrate uniformly aggressive pathologic features seem to be associated with mortality.

Background In breast cancer patients with nodal metastases at presentation, false-negative rates <10% have been demonstrated for sentinel node biopsy (SLNB) after neoadjuvant chemotherapy (NAC) when ≥3 negative sentinel nodes (SLNs) are retrieved, but the frequency with which axillary dissection (ALND) can be avoided is uncertain. Methods Among 534 prospectively identified consecutive patients with clinical stage II–III cancer receiving NAC from 11/2013–11/2015, all biopsy-proven node-positive (N+) cases were identified. Patients who were clinically node-negative post-NAC were SLNB-eligible. ALND was indicated for failed mapping, <3 SLNs retrieved, or positive SLNs. Results Of 288 N+ patients, 195 completed surgery. 132/195 (68%) were SLNB-eligible. Of these, median age was 50yrs, 73(55%) were ER+, 21(16%) ER−/HER2+, 38(29%) triple negative. SLNB was deferred intraoperatively in 4 cases. Among 128 SLNB attempts, ≥3 SLNs were retrieved in 110 (86%), 1–2 SLNs in 15(12%), 3 (2%) failed mapping. ALND was indicated in 66 cases: 54(82%) for positive SLNs, 9(14%) for <3 negative SLNs, 3(4%) for failed mapping. 17% with <3 negative SLNs retrieved had persistent disease. 62/128 (48%) had SLNB alone with ≥3 SLNs retrieved. Among 195 N+ patients completing surgery, nodal pathologic complete response (pCR) was achieved in 49%, ranging from 21% in ER+/HER2− to 97% in ER−/HER2+ cases, and was significantly more common than breast pCR in ER+/HER2− and triple-negative cases. Conclusions Nearly 70% of N+ patients were SLNB-eligible post-NAC. ALND was avoided in 48%, supporting the role of NAC in reducing the need for ALND among patients presenting with nodal metastases.

Objective To determine rates of axillary dissection (ALND) and nodal recurrence in patients eligible for ACOSOG Z0011. Summary Background Data Z0011 demonstrated that patients with cT1-2N0 breast cancers and 1–2 involved sentinel lymph nodes (SLNs) having breast-conserving therapy (BCT) had no difference in locoregional recurrence or survival after SLN biopsy alone or ALND. The generalizability of the results and importance of nodal radiotherapy (RT) is unclear. Methods Patients eligible for Z0011had SLN biopsy alone. Prospectively defined indications for ALND were metastases in ≥3 SLNs or gross extracapsular extension. Axillary imaging was not routine. SLN and ALND groups and radiation fields were compared with chi-square and t-tests. Cumulative incidence of recurrences was estimated with competing risk analysis. Results From 8/2010–12/2016, 793 patients met Z0011 eligibility criteria and had SLN metastases. 130 (16%) had ALND; ALND did not vary based on age, estrogen receptor, progesterone receptor, or HER2 status. 5-year event-free survival after SLN alone is 93% with no isolated axillary recurrences. Cumulative 5-year rates of breast+nodal and nodal+distant recurrence were each 0.7%. In 484 SLN-only patients with known RT fields (103 prone, 280 supine tangent, 101 breast+nodes) and follow-up≥12 months, the 5-year cumulative nodal recurrence rate was 1% and did not differ significantly by RT fields. Conclusions We confirm that even without preoperative axillary imaging or routine use of nodal RT, ALND can be avoided in a large majority of Z0011-eligible patients with excellent regional control. This approach has the potential to spare substantial numbers of women the morbidity of ALND.

Low-volume SLN disease after NAC is not an indicator of a low risk of additional positive axillary nodes and remains an indication for ALND, even when not detected on intraoperative FS.

Background In the setting where determining extent of residual disease is key for surgical planning after neoadjuvant chemotherapy (NAC), herein we evaluate reliability of MRI in predicting pathologic complete response (pCR) of the breast primary and axillary nodes following NAC. Study Design Patients who had MRI before and after NAC between 06/2014–08/2015 were identified in a prospective database following IRB approval. Post NAC-MRI of the breast and axillary nodes was correlated with residual disease on final pathology. PCR was defined as absence of invasive and in situ disease. Results We analyzed 129 breast cancers. Median patient age was 50.8 years (range 27.2–80.6). Tumors were HER2 amplified in 52/129 (40%), estrogen receptor-positive/HER2-negative in 46/129 (36%) and triple negative in 31/129 (24%), with respective pCR rates of 50%, 11% and 29%. Median tumor size pre- and post-NAC MRI were 4.1cm and 1.45cm, respectively. MRI had a positive predictive value of 63.4% (26/41) and negative predictive value of 84.1% (74/88) for in-breast pCR. Axillary nodes were abnormal on pre-NAC MRI in 97 cases; 65 had biopsy-confirmed metastases. The nodes normalized on post-NAC MRI in 33/65 (51%); axillary pCR was present in 22/33 (67%). In 32 patients with proven nodal metastases and abnormal nodes on post-NAC MRI, 11 achieved axillary pCR. In 32 patients with normal nodes on pre- and post-NAC MRI, 6 (19%) had metastasis on final pathology. Conclusions Radiologic complete response by MRI does not predict pCR with adequate accuracy to replace pathologic evaluation of the breast tumor and axillary nodes.

Ductal carcinoma in situ (DCIS) accounts for 20% of all newly diagnosed breast cancers. Mastectomy was once the gold standard for the treatment of DCIS; however, breast-conserving surgery (BCS) has been adopted as the treatment of choice for patients with small, screen-detected lesions. Both adjuvant radiation and hormonal therapy following BCS have been demonstrated in randomized trials to reduce the risk of invasive recurrence, but neither affects survival. With the variety of surgical and adjuvant treatment options available, there has been great interest in tailoring the treatment to the individual, with the goal of optimizing the balance of risks and benefits according to the values and priorities of the woman herself. Prospective studies of women with “low-risk” DCIS have successfully identified women at lower than average risk, but have not achieved the goal of identifying a subset of women with DCIS at minimal risk of recurrence after surgical excision alone.

Background Neoadjuvant chemotherapy (NAC) is used to convert patients with inoperable locally advanced breast cancer (LABC) to operability, but has not traditionally been used to avoid mastectomy or axillary dissection in this subset. The purpose of this study was to determine rates of pathologic complete response (pCR) in LABC patients and identify factors predictive of pCR to determine if responding patients might be suitable for limited surgery. Methods From 2006-2016, 1522 patients received NAC followed by surgery; 321 had advanced disease in the breast (cT4) and/or in the nodes (cN2/N3). pCR rates were assessed by T and N stage, and receptor subtype. Results Of 321 LABC patients, 223 were cT4, 77 cN2, and 82 cN3. 43% were hormone receptor (HR)+/HER2-, 23% triple negative, and 34% HER2+. The overall pCR rate was 25% and differed by receptor subtype (HR+/HER2- 7%; triple negative 23%; HER2+ 48%;p<0.001). Breast pCR occurred in 27% and was similar in T4 vs. non-T4 disease (29% vs. 22%,p=0.26). Nodal pCR was achieved in 38% of cN+ patients and did not differ by nodal stage (cN1 43%, cN2 36%, cN3 32%; p=0.23). Nodal pCR was significantly more common than breast pCR (p=0.014) across all tumor subtypes. Receptor subtype was the only predictor of overall pCR (p<0.001). Conclusion In patients with LABC, pCR after NAC was seen in 25%, and did not differ by T or N stage. Tumor biology, but not extent of disease, predicted pCR. Studies assessing feasibility of surgical downstaging with NAC in LABC patients are warranted.

Background The benefit of neoadjuvant therapy (NAC) in patients with estrogen receptor positive (ER+) HER2− breast cancers and in invasive lobular cancer (ILC) is uncertain due to low rates of pathologic complete response (pCR). Our aim was to determine if pathologic features can identify subsets likely to benefit from NAC. Methods Patients with stage I–III ER+, HER2− breast cancer receiving NAC were retrospectively reviewed. Endpoints were downstaging to breast-conserving surgery (BCS) and nodal pCR after NAC. Patients were grouped by progesterone receptor (PR) status and grade/differentiation (high grade or poor [HP] vs non-HP). Results From 2007–2016, 402 ER+/HER2− cancers in patients receiving NAC were identified. Median age was 50 years, 98% were clinical stage II–III, and 75% cN+. Overall pCR rate was 5%; breast pCR in 7%, nodal pCR in 15% of cN+ patients (p<.0001). Patients with ILC initially ineligible for BCS (n=56) were less likely to downstage than those with ductal (n=183), 16% vs 48% (p≤.0001); with a similar trend in the axilla (p=.086). Rates of BCS eligibility after NAC were highest in PR−/HP (62%) and lowest in PR+/non-HP (29%) patients (p=.005). In the axilla, nodal pCR among cN+ patients (n=301) ranged from 0–35% (p<.0001) within these groups, and was most frequent in PR−/HP patients. Conclusions ER+/HER2− patients most likely to benefit from NAC are those with PR− and HP tumors. Patients with ILC are unlikely to downstage in the breast or axilla compared to IDC. Use of these criteria can assist in defining initial treatment approach.