Patterns of completion axillary dissection for patients with cT1-2N0 breast cancer undergoing total mastectomy with positive sentinel lymph nodes

BACKGROUND AND OBJECTIVES

The ACOSOGZ0011 trial found that overall survival (OS) for patients with 1-2 positive nodes undergoing sentinel lymph node biopsy-alone (SLNB) was noninferior to completion axillary lymph node dissection (ALND), but excluded patients undergoing mastectomy. Our study examined patterns of ALND and its relationship with OS for SLNB-positive patients undergoing mastectomy.

METHODS

The National Cancer Database was queried (2010-2017) for patients with cT1-2N0 breast cancer undergoing mastectomy with positive sentinel lymph nodes. Clinical data were compared.

RESULTS

Of 20 001 patients, 11 574 (57.9%) underwent SLNB + ALND, and 8427 (42.1%) had SLNB-alone. The SLNB + ALND group had more positive nodes (mean 2.6 vs. 1.3, p < 0.001) and more frequently received nodal radiation (33.4% vs. 28.9%, p < 0.001). Patients diagnosed in later years were less likely to undergo ALND (2010: reference; 2017: odds ratio: 0.29, 95% confidence interval [CI]: 0.25-0.33, p < 0.001). ALND (hazard ratio [HR]: 0.97, 95% CI: 0.89-1.06, p = 0.49) and nodal radiation (HR: 0.92, 95% CI: 0.83-1.02, p = 1.06) were not independently associated with OS. Propensity-score matched 5-year OS was similar (SLNB + ALND: 90.9% vs. SLNB-alone: 90.3%, p = 0.65).

CONCLUSION

For patients undergoing mastectomy for cT1-2N0 breast cancer with positive SLNB, SLNB-alone was common and increased over time. Axillary radiation was not routinely delivered in the SLNB-alone group. Completion ALND and nodal radiation were not associated with improved survival.

Omitting completion axillary lymph node dissection after detection of sentinel node micrometastases in breast cancer: first results from the prospective SENOMIC trial

BACKGROUND

Completion axillary lymph node dissection has been abandoned widely among patients with breast cancer and sentinel lymph node micrometastases, based on evidence from prospective RCTs. Inclusion in these trials has been subject to selection bias, with patients undergoing mastectomy being under-represented. The aim of the SENOMIC (omission of axillary lymph node dissection in SENtinel NOde MICrometases) trial was to confirm the safety of omission of axillary lymph node dissection in patients with breast cancer and sentinel lymph node micrometastases, and including patients undergoing mastectomy.

METHODS

The prospective SENOMIC multicentre cohort trial enrolled patients with breast cancer and sentinel lymph node micrometastases who had breast-conserving surgery or mastectomy at one of 23 Swedish hospitals between October 2013 and March 2017. No completion axillary lymph node dissection was performed. The primary endpoint was event-free survival, with a trial accrual target of 452 patients. Survival proportions were based on Kaplan-Meier survival estimates.

RESULTS

The trial included 566 patients. Median follow-up was 38 (range 7-67) months. The 3-year event-free survival rate was 96.2 per cent, based on 26 reported breast cancer recurrences, including five isolated axillary recurrences. The unadjusted 3-year event-free survival rate was higher than anticipated, but differed between patients who had mastectomy and those who underwent breast-conserving surgery (93.8 versus 97.8 per cent respectively; P = 0.011). Patients who underwent mastectomy had significantly worse tumour characteristics. On univariable Cox proportional hazards regression analysis, patients who had mastectomy without adjuvant radiotherapy had a significantly higher risk of recurrence than those who underwent breast-conserving surgery (hazard ratio 2.91, 95 per cent c.i. 1.25 to 6.75).

CONCLUSION

After 3 years, event-free survival was excellent in patients with breast cancer and sentinel node micrometastases despite omission of axillary lymph node dissection. Long-term follow-up and continued enrolment of patients having mastectomy, especially those not receiving adjuvant radiotherapy, are of utmost importance.

Analyzing non-sentinel axillary metastases in patients with T3-T4 cN0 early breast cancer and tumor-involved sentinel lymph nodes undergoing breast-conserving therapy or mastectomy

Purpose

In the ACOSOG Z0011 trial, completing axillary lymph node dissection (cALND) did not benefit patients with T1–T2 cN0 early breast cancer and 1–2 positive sentinel lymph nodes (SLN) undergoing breast-conserving surgery (BCT). This paper reports cALND rates in the clinical routine for patients who had higher (T3–T4) tumor stages and/or underwent mastectomy but otherwise met the ACOSOG Z0011 eligibility criteria. Aim of this study is to determine cALND time trends and non-sentinel axillary metastases (NSAM) rates to estimate occult axillary tumor burden.

Methods

Data were included from patients treated in 179 German breast cancer centers between 2008 and 2015. Time-trend rates were analyzed for cALND of patients with T3–T4 tumors separated for BCT and mastectomy and regarding presence of axillary macrometastases or micrometastases.

Results

Data were available for 188,909 patients, of whom 19,009 were identified with 1–2 positive SLN. Those 19,009 patients were separated into 4 cohorts: (1) Patients with T1–T2 tumors receiving BCT (ACOSOG Z0011 eligible; n = 13,741), (2) T1–T2 with mastectomy (n = 4093), (3) T3–T4 with BCT (n = 269), (4) T3–T4 with mastectomy (n = 906). Among patients with T3–T4 tumors, cALND rates declined from 2008 to 2015: from 88.2 to 62.6% for patients receiving mastectomy and from 96.6 to 58.1% in patients receiving BCT. Overall rates for any NSAM after cALND for cohorts 1–4 were 33.4%, 42.3%, 46.9%, 58.8%, respectively.

Conclusions

The cALND rates have decreased substantially in routine care in patients with ‘extended’ ACOSOG Z0011 eligibility criteria. Axillary tumor burden is higher in these patients than in the ACOSOG Z0011 trial.

Do clinical trials truly mirror their target population? An external validity analysis of national register versus trial data from the Swedish prospective SENOMIC trial on sentinel node micrometastases in breast cancer

Purpose

Increasing evidence suggests that completion axillary lymph node dissection (ALND) may be omitted in breast cancer patients with limited axillary nodal metastases. However, the representativeness of trial participants for the original clinical practice population, and thus, the generalizability of published trials have been questioned. We propose the use of background data from national registers as a means to assess whether trial participants mirror their target population and to strengthen the generalizability and implementation of trial outcomes.

Methods

The Swedish prospective SENOMIC trial, omitting a completion ALND in breast cancer patients with sentinel lymph node micrometastases, reached full target accrual in 2017. To assess the generalizability of trial results for the target population, a comparative analysis of trial participants versus cases reported to the Swedish National Breast Cancer Register (NKBC) was performed.

Results

Comparing 548 trial participants and 1070 NKBC cases, there were no significant differences in age, tumor characteristics, breast surgery, or adjuvant treatment. Only the mean number of sentinel lymph nodes with micrometastasis per individual was lower in trial participants than in register cases (1.06 vs. 1.09, p = 0.037).

Conclusions

Patients included in the SENOMIC trial are acceptably representative of the Swedish breast cancer target population. There were some minor divergences between trial participants and the NKBC population, but taking these into consideration, upcoming trial outcomes should be generalizable to breast cancer patients with micrometastases in their sentinel lymph node biopsy.

Effect of the American College of Surgeons Oncology Group Z0011 trial on axillary management in breast cancer patients in the Australian setting

The American College of Surgeons Oncology Group Z0011 Trial demonstrated that early breast cancer patients with positive axillary sentinel lymph nodes treated with breast-conserving surgery and breast radiotherapy had no additional oncologic benefit of proceeding to an axillary lymph node dissection (ALND). The extent to which practice has changed in Australia remains unclear. The aim of this study was to investigate the effect of the Z0011 trial on the management of positive axillary sentinel nodes at an Australian institutional level. We reviewed all breast cancer cases treated at the Sydney Adventist Hospital over a 10-year period from 1 January 2008 to 31 December 2017. Patients who fulfilled the Z0011 trial criteria were selected. These patients were divided into two groups according to the year of surgery, before and after 1 January 2011 when the Z0011 study was published. Clinicopathologic data and axillary surgical management were compared. Of the 237 patients fulfilling the Z0011 trial criteria, there were 73 patients before and 158 patients after 1 January 2011. In the earlier group the rate of proceeding to an ALND following a positive sentinel node was 78.1% compared to 43.7% in the latter group (P < 0.0001). There was a significant decline in the rate of ALND over this 10-year period (r = -0.79, P = 0.006). The Z0011 trial has influenced the surgical management of the axilla leading to a significant reduction in the rate of an ALND in patients fulfilling the Z0011 trial criteria at our institution.

Evolution in practice patterns of axillary management following mastectomy in patients with 1-2 positive sentinel nodes

PURPOSE

The optimal management of breast cancer patients with a positive sentinel lymph node (SLN) who undergo mastectomy remains controversial. This study aimed to describe treatment patterns of patients with positive SLNs who undergo mastectomy using a large population-based database.

METHODS

The NCDB was queried for cT1-2N0 breast cancer patients treated with mastectomy between 2006 and 2014 who had 1-2 positive SLNs. Patients receiving neoadjuvant chemotherapy were excluded. Axillary management included SLN dissection (SLND) alone, axillary lymph node dissection (ALND), post-mastectomy radiation (PMRT) alone, and ALND + PMRT. Trends of axillary management and patient characteristics were examined.

RESULTS

Among 12,190 patients who met study criteria, the use of ALND dropped with a corresponding increase in other approaches. In 2006, 34% of patients had SLND alone, 47% ALND, 8% PMRT and 11% ALND + PMRT. By 2014, 37% had SLND, 23% ALND, 27% PMRT and 13% ALND + PMRT. Patients who underwent SLND alone were older (mean 60.6 years) with more comorbidities (Charlson-Deyo score > 2), smaller primary tumors (mean 2.1 cm), well-differentiated histology, hormone receptor-positive, HER2-negative tumors, without lymphovascular invasion (all P values < 0.01). Treatment with SLND alone was more likely if patients had only one positive SLN (P < 0.001) or micrometastatic disease (P < 0.001), and were treated at community centers compared with academic centers (P < 0.001).

CONCLUSIONS

The management of breast cancer patients undergoing mastectomy with positive SLNs has evolved over time with decreased use of ALND and increased use of radiation. Some patient subsets are underrepresented in recent clinical trials, and therefore, future trials should focus on these patients.

Contemporary Evaluation of Breast Lymph Nodes in Anatomic Pathology

OBJECTIVES

Management of the axilla in breast cancer patients has evolved considerably since the introduction of the sentinel lymph node (SLN) biopsy in the 1990s. Several new clinical and technological developments in the last decade warrant special consideration due to their impact on pathology practice.

METHODS

This review covers the SLN biopsy procedure, issues in the histopathologic and molecular diagnosis of the SLN, and most importantly, evidence from recent practice-changing clinical trials.

RESULTS

ACOSOG Z0011, IBCSG 23-01, and AMAROS trials have shown that early-stage breast cancer patients who have limited metastatic involvement of the SLNs do not benefit from completion axillary dissections.

CONCLUSIONS

It is not necessary for pathologists to search for all small metastases to predict non-SLN involvement, regional recurrence, or death due to disease. Processing should be designed with the goal of detecting macrometastases. Multiple levels, routine immunohistochemistry, and molecular testing are not recommended.

Survival and axillary recurrence following sentinel node-positive breast cancer without completion axillary lymph node dissection: the randomized controlled SENOMAC trial

Background

The role of axillary lymph node dissection (ALND) has increasingly been called into question among patients with positive sentinel lymph nodes. Two recent trials have failed to show a survival difference in sentinel node-positive breast cancer patients who were randomized either to undergo completion ALND or not. Neither of the trials, however, included breast cancer patients undergoing mastectomy or those with tumors larger than 5 cm, and power was debatable to show a small survival difference.

Methods

The prospective randomized SENOMAC trial includes clinically node-negative breast cancer patients with up to two macrometastases in their sentinel lymph node biopsy. Patients with T1-T3 tumors are eligible as well as patients prior to systemic neoadjuvant therapy. Both breast-conserving surgery and mastectomy, with or without breast reconstruction, are eligible interventions. Patients are randomized 1:1 to either undergo completion ALND or not by a web-based randomization tool. This trial is designed as a non-inferiority study with breast cancer-specific survival at 5 years as the primary endpoint. Target accrual is 3500 patients to achieve 80% power in being able to detect a potential 2.5% deterioration of the breast cancer-specific 5-year survival rate. Follow-up is by annual clinical examination and mammography during 5 years, and additional controls after 10 and 15 years. Secondary endpoints such as arm morbidity and health-related quality of life are measured by questionnaires at 1, 3 and 5 years.

Discussion

Several large subgroups of breast cancer patients, such as patients undergoing mastectomy or those with larger tumors, have not been included in key trials; however, the use of ALND is being questioned even in these groups without the support of high-quality evidence. Therefore, the SENOMAC Trial will investigate the need of completion ALND in case of limited spread to the sentinel lymph nodes not only in patients undergoing any breast surgery, but also in neoadjuvantly treated patients and patients with larger tumors.

Trial registration

NCT 02240472, retrospective registration date September 14, 2015 after trial initiation on January 31, 2015.