The use of sentinel lymph node surgery after neoadjuvant chemotherapy for patients who present with cN1 breast cancer provides an opportunity to avoid axillary lymph node dissection for those patients who have eradication of their nodal disease with chemotherapy. Since the initial publication of prospective trials demonstrating the false-negative rate of sentinel lymph node (SLN) surgery in this setting, this practice has been increasing. [1][2][3][4] A recent survey of the American Society of Breast Surgeons (ASBrS) reported that 85% of respondents offered SLN surgery to some patients in this setting. 5

Objective To determine the impact of tumor biology on rates of breast-conserving surgery and pathologic complete response (pCR) after neoadjuvant chemotherapy. Summary Background Data The impact of tumor biology on the rate of breast-conserving surgery after neoadjuvant chemotherapy has not been well studied. Methods We used data from ACOSOG Z1071, a prospective, multicenter study assessing sentinel node surgery after neoadjuvant chemotherapy in patients presenting with node-positive breast cancer from 2009 through 2011, to determine rates of breast-conserving surgery and pCR after chemotherapy by approximated biologic subtype. Results Of the 756 patients enrolled on Z1071, 694 had findings available from pathologic review of breast and axillary specimens from surgery after chemotherapy. Approximated subtype was triple-negative in 170 (24.5%) patients, HER2-positive in 207 (29.8%), and hormone-receptor-positive, HER2-negative in 317 (45.7%). Patient age and clinical tumor and nodal stage at presentation did not differ across subtypes. Rates of breast-conserving surgery were significantly higher in patients with triple-negative (46.8%) and HER2-positive tumors (43.0%) than in those with hormone-receptor-positive, HER2-negative tumors (34.5%) (P = 0.019). Rates of pCR in both the breast and axilla were 38.2% in triple-negative, 45.4% in HER2-positive, and 11.4% in hormone-receptor-positive, HER2-negative disease (P < 0.0001). Rates of pCR in the breast only and the axilla only exhibited similar differences across tumor subtypes. Conclusions Patients with triple-negative and HER2-positive breast cancers have the highest rates of breast-conserving surgery and pCR after neoadjuvant chemotherapy. Patients with these subtypes are most likely to be candidates for less invasive surgical approaches after chemotherapy.

Objective To evaluate factors affecting sentinel lymph node (SLN) identification after neoadjuvant chemotherapy (NAC) in patients with initial node-positive breast cancer. Summary Background Data SLN surgery is increasingly used for nodal staging after NAC and optimal technique for SLN identification is important. Methods The American College of Surgeons Oncology Group Z1071 prospective trial enrolled clinical T0-4,N1-2,M0 breast cancer patients. Following NAC, SLN surgery and axillary lymph node dissection (ALND) were planned. Multivariate logistic regression modeling assessing factors influencing SLN identification was performed. Results Of 756 patients enrolled, 34 women withdrew, 21 were ineligible, 12 underwent ALND only, and 689 had SLN surgery attempted. At least one SLN was identified in 639 patients (92.7%: 95%CI: 90.5–94.6%). Among factors evaluated, mapping technique was the only factor found to impact SLN identification; with use of blue dye alone increasing the likelihood of failure to identify the SLN relative to using radiolabelled colloid +/− blue dye (p=0.006; OR=3.82 95%CI: 1.47-9.92). The SLN identification rate was 78.6% with blue dye alone; 91.4% with radiolabelled colloid and 93.8% with dual mapping agents. Patient factors (age, BMI), tumor factors (clinical T or N stage), pathologic nodal response to chemotherapy, site of tracer injection and length of chemotherapy treatment did not significantly affect the SLN identification rate. Conclusions The SLN identification rate after NAC was higher when mapping was performed using radiolabelled colloid alone or with blue dye compared to blue dye alone. Optimal tracer use is important to ensure successful identification of SLN(s) after NAC.

The strategy of re-excising close margins resulted in a predicted cost of $18.8 million per year. This does not include hospital costs, the cost of surgical complications after re-excision, and underestimates the potential savings by using Medicare reimbursement rates.