Safety of Targeted Axillary Dissection After Neoadjuvant Therapy in Patients With Node-Positive Breast Cancer

IMPORTANCE

The increasing use of neoadjuvant systemic therapy (NST) has led to substantial pathological complete response rates in patients with initially node-positive, early breast cancer, thereby questioning the need for axillary lymph node dissection (ALND). Targeted axillary dissection (TAD) is feasible for axillary staging; however, data on oncological safety are scarce.

OBJECTIVE

To assess 3-year clinical outcomes in patients with node-positive breast cancer who underwent TAD alone or TAD with ALND.

DESIGN, SETTING, AND PARTICIPANTS

The SenTa study is a prospective registry study and was conducted between January 2017 and October 2018. The registry includes 50 study centers in Germany. Patients with clinically node-positive breast cancer underwent clipping of the most suspicious lymph node (LN) before NST. After NST, the marked LNs and sentinel LNs were excised (TAD) followed by ALND according to the clinician's choice. Patients who did not undergo TAD were excluded. Data analysis was performed in April 2022 after 43 months of follow-up.

EXPOSURE

TAD alone vs TAD with ALND.

MAIN OUTCOMES AND MEASURES

Three-year clinical outcomes were evaluated.

RESULTS

Of 199 female patients, the median (IQR) age was 52 (45-60) years. A total of 182 patients (91.5%) had 1 to 3 suspicious LNs; 119 received TAD alone and 80 received TAD with ALND. Unadjusted invasive disease-free survival was 82.4% (95% CI, 71.5-89.4) in the TAD with ALND group and 91.2% (95% CI, 84.2-95.1) in the TAD alone group (P = .04); axillary recurrence rates were 1.4% (95% CI, 0-54.8) and 1.8% (95% CI, 0-36.4), respectively (P = .56). Adjusted multivariate Cox regression indicated that TAD alone was not associated with an increased risk of recurrence (hazard ratio [HR], 0.83; 95% CI, 0.34-2.05; P = .69) or death (HR, 1.07; 95% CI, 0.31-3.70; P = .91). Similar results were obtained for 152 patients with clinically node-negative breast cancer after NST (invasive disease-free survival: HR, 1.26; 95% CI, 0.27-5.87; P = .77; overall survival: HR, 0.81; 95% CI, 0.15-3.83; P = .74).

CONCLUSIONS AND RELEVANCE

These results suggest that TAD alone in patients with mostly good clinical response to NST and at least 3 TAD LNs may confer survival outcomes and recurrence rates similar to TAD with ALND.

Phenotype Discordance between Primary Tumor and Metastasis Impacts Metastasis Site and Outcome: Results of WSG-DETECT-PriMet

Introduction

Tumor biological factors of breast cancer (BC) such as hormone receptor (HR) status, HER2 status, and grade can differ in the metastatic cascade from primary to lymph node (LN) metastasis and to distant metastatic tissue. Systematic data regarding therapeutic consequences are yet limited.

Methods

We conducted a prospectively planned, retrospective cohort study comparing BC phenotype in tissue from primary tumors (PTs), locoregional LN metastases, and disease recurrence (DR). HR and HER2 as well as tumor grade in PTs and DR were obtained by a database search. No centralized biomarker testing was performed. The impact of changes in tumor biological factors on post-recurrence survival (PRS) and overall survival was analyzed.

Results

PriMet comprises 635 patients (LN tissue in 142 patients). Discrepancies for HR or HER2 status between PT and DR were observed in 18.7 and 21.6% of cases, respectively. For HR status, positivity of PT and negativity of DR was seen more often (13.2%) than vice versa (5.5%). For HER2 status, negativity of the primary and positivity of DR was seen more often (14.9%) than vice versa (6.7%). Discordance was more often observed between PT and LN metastasis compared to LN versus DR. However, numbers were small. Compared to concordant non-triple-negative (TN) disease, concordant TN disease showed significantly inferior PRS.

Conclusion

We demonstrate receptor discordance to occur relatively frequently between PT, LN metastasis, and DR and to impact patient prognosis. However, clinical consequences of receptor discordance need to be drawn with caution considering clinical aspects as well as tumor biology.

Abstract P5-04-02: Biopsy of metastases impacts treatment choice and patient outcome in breast cancer – Final results of the WSG/DETECT PRIMET study

Background: Changes in tumor biology (e.g., hormone receptor (HR) / HER2 status or grading) between primary tumor (PT) and metastatic tissue (MT) could impact outcome and treatment choice following first recurrence in breast cancer (BC).

Methods: PRIMET is a prospectively planned, retrospective multicenter quality assurance study comparing BC phenotype in tissue from PT, involved lymph nodes (LN) of primary disease, and disease recurrence (DR). PRIMET comprises 635 patients from WSG and DETECT trial groups (11 centers), whose BC was diagnosed between 1980 and 2010; follow-up continued until mid-2012. Patients with unilateral primary BC suffering subsequent local-regional and / or distant DR (LDR / DDR) were included. Clinical data including ER, PR, HER2, and grade were obtained from a systematic chart review in PT and DR; in two centers, these factors were also measured in LN by central pathology. Dependence of post-recurrence survival (PRS) on changes in tumor biological factors was analyzed.

Results: Data from 635 patients (including 592 cM0, of whom 46% had LDR only) were available for analysis. Median follow-up in patients alive at analysis was 101 months. Considering cM0 patients, median overall survival (OS) was 176 months; median recurrence-free survival (RFS) was 48 months (DDR present: 45 months; LDR only: 50 months). Median PRS was 59 months (DDR present: 45 months; LDR only: 127 months). In patients with first DR within 18 months, median PRS was 29 months, in others 79 months. HR status in PT/MT was: 61.5% (+/+), 13.2% (+/-), 5.5% (-/+) 19.8% (-/-). Of the HR “switches” in either direction with LN biopsy available, about half already occurred in lymph nodes. HER2 status in PT/MT was: 14.6% (+/+), 6.7% (+/-), 14.9% (-/+) 63.8% (-/-). With LN biopsy available, most losses of HER2 overexpression were already observed in LN tissue, whereas acquired HER2 overexpression was observed in about half of LN biopsies. Triple negative (TN: HR-, HER2-) percentages were 74.4% (non-TN/non-TN), 9.0% (non-TN/TN), 6.1% (TN/non-TN), 10.5% (TN/TN).

Compared to HR+/+, loss of HR+ status (HR+/-) was significantly associated with poorer PRS (hazard ratio: 1.62; p = 0.01). Significantly better PRS was associated with a switch from G3 to G1/2 (hazard ratio: 0.47; p = 0.02). Tumors that switched to TN or that lost HER2 overexpression showed trends toward poorer PRS. Persistent TN was associated with poorer PRS than other combinations.

Among patients with DDR, metastasis in bone only was associated with better PRS than primary or visceral (CNS, lung, liver, etc.) metastasis. Among patients with visceral metastasis, negative HR status in metastasis was associated with poorer survival than in HR+/+ not only for HR-/- (p = 0.02), but also for HR+/- (p = 0.04).

Conclusions:

Tumor biology of primary and metastatic tissue differed in a substantial fraction of patients (HR: 19%; HER2: 22%, TN: 18%); more than half of all changes occurred already in LN. Status changes particularly loss of HR+ status, had significant prognostic impact. We can expect a switch in HR or HER2 status (or both) in about 38% of metastatic tissue biopsies, with presumably important clinical therapeutic consequences, in particular regarding targeted therapies.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-04-02.