The impact of nodal micrometastasis on mortality among women with early-stage breast cancer

Negative Survival Impact of Occult Lymph Node Involvement in Small HER2-Positive Early Breast Cancer Treated by Up-Front Surgery

(1) Background: The independent negative prognostic value of isolated tumor cells or micro-metastases in axillary lymph nodes has been established in triple-negative breast cancers (BC). However, the prognostic significance of pN0(i+) or pN1mi in HER2-positive BCs treated by primary surgery remains unexplored. Therefore, our objective was to investigate the impact of pN0(i+) or pN1mi in HER2-positive BC patients undergoing up-front surgery on their outcomes. (2) Methods: We retrospectively analyzed 23,650 patients treated in 13 French cancer centers from 1991 to 2013. pN status was categorized as pN0, pN0(i+), pN1mi, and pNmacro. The effect of pN0(i+) or pN1mi on outcomes was investigated both in the entire cohort of patients and in pT1a-b tumors. (3) Results: Of 1771 HER2-positive BC patients included, pN status distributed as follows: 1047 pN0 (59.1%), 60 pN0(i+) (3.4%), 118 pN1mi (6.7%), and 546 pN1 macro-metastases (30.8%). pN status was significantly associated with sentinel lymph node biopsy, axillary lymph node dissection, age, ER status, tumor grade, and size, lymphovascular invasion, adjuvant systemic therapy (ACt), and radiation therapy. With 61 months median follow-up (mean 63.2; CI 95% 61.5-64.9), only pN1 with macro-metastases was independently associated with a negative impact on overall, disease-free, recurrence-free, and metastasis-free survivals in multivariate analysis. In the pT1a-b subgroup including 474 patients, RFS was significantly decreased in multivariate analysis for pT1b BC without ACt (HR 2.365, 1.04-5.36, p = 0.039) and for pN0(i+)/pN1mi patients (HR 2.518, 1.03-6.14, p = 0.042). (4) Conclusions: Survival outcomes were not adversely affected by pN0(i+) and pN1mi in patients with HER2-positive BC. However, in the case of pT1a-b HER2-positive BC, a negative impact on RFS was observed specifically for patients with pN0(i+) and pN1mi diseases, particularly among those with pT1b tumors without ACt. Our findings highlight the importance of considering the pN0(i+) and pN1mi status in the decision-making process when discussing trastuzumab-based ACt for these patients.

The prognostic significance of further axillary dissection for sentinel lymph node micrometastases in female breast cancer: A competing risk analysis using the SEER database

BACKGROUND

Sentinel lymph node (SLN) biopsy has been widely recognized as an excellent surgical and staging procedure for early-stage breast cancer, and its development has greatly improved the detection of micrometastases. However, the axillary treatment of micrometastasis has been the subject of much debate.

METHODS

We identified 427,131 women diagnosed with breast cancer from 2010 to 2018 in the Surveillance, Epidemiology, and End Results (SEER) database. Patients whose nodal status was micrometastases (pTxN1miM0) were classified into two groups: the SLNB only group and SLNB with complete ALND group, and we used these classifications to carry out propensity-score matching (PSM) analysis. The primary and secondary endpoints were OS and BCSS, respectively. We then implemented the Kaplan-Meier method and Cox proportional hazard model and used Fine and Gray competitive risk regression to identify factors associated with the risk of all-cause mortality.

RESULTS

After the PSM, 1,833 pairs were included in total. The SLNB with complete ALND showed no significant difference in OS (HR=1.04, 95% CI: 0.84-1.28, P=0.73) or BCSS (HR= 1.03, 95% CI: 0.79-1.35, P=0.82) compared to the SLNB only group, and axillary treatment was not associated with breast cancer-specific death (BCSD) (HR=1.13, 95% CI: 0.86-1.48, P=0.400) or other cause-specific death (OCSD) (HR=0.98, 95% CI:0.70-1.38, P=0.920). There was no statistically significant difference in the cumulative incidence of BCSD (Grey's test, P=0.819) or OCSD (Grey's test, P=0.788) for between the two groups either. For different molecular subtypes, patients in the SLNB only group showed no statistically significant differences from those in the SLNB with complete ALND group with Luminal A (HR=1.00, 95% CI:0.76-1.32, P=0.98) or Luminal B (HR=0.82, 95% CI:0.42-1.62, P=0.55) but similar OS to HER2-enriched (HR=1.58, 95% CI:0.81-3.07, P=0.19) or triple negative breast cancers (HR=1.18, 95% CI:0.76-1.81, P=0.46).

CONCLUSIONS

Our results suggest that in early breast cancer patients with micrometastasis, complete ALND does not seem to be required and that SLNB suffices to control locoregional and distant disease, with no significant adverse effects on survival compared to complete ALND.

OPTimizing Irradiation through Molecular Assessment of Lymph node (OPTIMAL): a randomized clinical trial

BACKGROUND AND PURPOSE

In breast cancer (BC) patients, the involvement of four or more lymph nodes (LN) is an indication of regional irradiation. The optimal treatment strategy remains unclear when fewer nodes are involved and lymphadenectomy is not performed. We designed a clinical trial to show the non-inferiority of Incidental (INC) compared to intentional (INT) irradiation of axillary nodes in patients with early-stage BC and low burden LN involvement.

MATERIALS AND METHODS

BC patients, cN0 (n = 487) undergoing breast conservation surgery and sentinel node biopsy, with total tumor load assessed by OSNA (One-Step Nucleic Acid Amplification) of 250-15,000 copies mRNA CK19/µL in sentinel LN were randomized to receive INC or INT nodal irradiation. The primary endpoint was 5-year disease-free survival (DFS). Secondary endpoints were locoregional recurrence (LRR), distant recurrence (DR), and acute and chronic toxicity (CT).

RESULTS

Five-years DFS were 93.7% (INC) and 93.8% (INT) (difference 0.1% [one-sided 95% CI < 5.7%]; non-inferiority p = 0.075). Cumulative Incidences of LRR were 3.5% (INC) and 3.4% (INT) (difference of 0.1% [<4.8%]; p = 0.021), and 5% (INC) and 3.5% (INT) (difference 1.4% [<6.0%]; non-inferiority p = 0.101) for DR. CT was more Incident with INT (26.9%) than with INC (19.2%), though the difference was not statistically significant (HR 1.39 [95% CI: 0.92, 2.10]; p = 0.11).

CONCLUSION

Intentional does not outperform incidental irradiation by more than 5.7% in terms of 5-year DFS, 4.8% for LRR, and 6% for DR.

REGISTRATION NUMBER

ClinicalTrials.gov Identifier: NCT02335957.

Lack of prognostic impact of sentinel node micro-metastases in endocrine receptor-positive early breast cancer: results from a large multicenter cohort☆

Background

Prognostic impact of lymph node micro-metastases (pN1mi) has been discordantly reported in the literature. The need to clarify this point for decision-making regarding adjuvant therapy, particularly for patients with endocrine receptor (ER)-positive status and HER2-negative tumors, is further reinforced by the generalization of gene expression signatures using pN status in their recommendation algorithm.

Patients and methods

We retrospectively analyzed 13 773 patients treated for ER-positive breast cancer in 13 French cancer centers from 1999 to 2014. Five categories of axillary lymph node (LN) status were defined: negative LN (pN0i−), isolated tumor cells [pN0(i+)], pN1mi, and pN1 divided into single (pN1 = 1) and multiple (pN1 > 1) macro-metastases (>2 mm). The effect of LN micro-metastases on outcomes was investigated both in the entire cohort of patients and in clinically relevant subgroups according to tumor subtypes. Propensity-score-based matching was used to balance differences in known prognostic variables associated with pN status.

Results

As determined by sentinel LN biopsy, 9427 patients were pN0 (68.4%), 546 pN0(i+) (4.0%), 1446 pN1mi (10.5%) and 2354 pN1 with macro-metastases (17.1%). With a median follow-up of 61.25 months, pN1 status, but not pN1mi, significantly impacted overall survival (OS), disease-free survival (DFS), metastasis-free survival (MFS), and breast-cancer-specific survival. In the subgroup of patients with known tumor subtype, pN1 = 1, as pN1 > 1, but not pN1mi, had a significant prognostic impact on OS. DFS and MFS were only impacted by pN1 > 1. Similar results were observed in the subgroup of patients with luminal A-like tumors (n = 7101). In the matched population analysis, pN1macro, but not pN1mi, had a statistically significant negative impact on MFS and OS.

Conclusion

LN micro-metastases have no detectable prognostic impact and should not be considered as a determining factor in indicating adjuvant chemotherapy. The evaluation of the risk of recurrence using second-generation signatures should be calculated considering micro-metastases as pN0.

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LN micro-metastases have no detectable prognostic impact.

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pN1 status, but not pN1mi, significantly impacted overall survival, disease-free survival, metastasis-free survival.

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In the subgroup of patients with known tumor subtype, pN1=1, as pN1>1, but not pN1mi, had a significant prognostic impact on OS.

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LN micro-metastases should not be considered as a determining factor in indicating adjuvant chemotherapy.

Clinical effect of the pathological axillary assessment method in breast cancer without clinical nodal metastasis

BACKGROUND

This study aimed to assess the clinical effect of the pathological axillary assessment method in breast cancer without clinical lymph node metastasis.

METHODS

Data of patients with clinically node-negative breast cancer were retrospectively reviewed. The study period was divided into early (January 2000-July 2007) and late (August 2007-December 2014) periods based on the pathological assessment method used (single-sectional and detailed multi-sectional lymph node processing). In the late period, lymph nodes were evaluated at six levels including immunohistochemistry on each 1.5-2 mm interval section. The axillary diagnostic accuracy and role of chemotherapy were assessed.

RESULTS

In 1698 patients, 27 isolated tumor cells (ITCs), 39 micrometastases, and 205 macrometastases were noted. The sensitivity for pathological N0 diagnosis was dependent on clinical T stage, Tis (97.8%), T1 (83.0%), T2 (74.2%), T3 (54.5%), and T4 (63.6%). ITCs and micrometastases were detected only in the late period, and 84.7% and 91.6% of cases in the early and late period, respectively, did not have macrometastases. The 5-year disease-free interval (DFI) rates were 95.2% in node-negative cases, 98.4% in ITCs/micrometastases, and 91.4% in macrometastases (P < 0.001). In multivariate analysis, the predictor for DFI was estrogen receptor negativity (P = 0.013). Chemotherapy did not improve DFI in patients with node-positive breast cancer.

CONCLUSIONS

The detailed multi-sectional pathological assessment of axillary lymph nodes detected ITCs and micrometastases. Implementation of chemotherapy should not be based on the minimal nodal metastasis and this type of serially nodal sectioned processing had little clinical significance.

Prognostic and Predictive Value of the American Joint Committee on Cancer Pathological Prognostic Staging System in Nodal Micrometastatic Breast Cancer

Introduction

To investigate the prognostic and predictive effect of the American Joint Committee on Cancer (AJCC) 8^th edition pathological prognostic staging system in patients with T1-2N1micM0 breast cancer who underwent mastectomy.

Methods

Data from T1-2N1micM0 breast cancer patients who underwent mastectomy from 2010–2014 were obtained from the Surveillance, Epidemiology, and End Results program. The chi-square test, binomial logistics regression, receiver-operating characteristics curve, competing-risk regression model, Cox proportional hazards regression model, and proportional hazard assumption were used for statistical analyses.

Results

We identified 4,729 patients, including 1,062 patients were received postmastectomy radiotherapy (PMRT). Stage change occurred in 88.2% of the patients, of which 84.4% were downstaged and 3.7% were upstaged. Patients with higher pathological prognostic stages were independently predicted to receive PMRT. The 5-year breast cancer-specific survival (BCSS) was 97.5, 93.7, 90.1, 86.0, and 73.5% in disease stages IA, IB, IIA, IIB, and IIIA, respectively, according to the 8^th edition criteria (P < 0.001). The AJCC 8^th edition demonstrated moderate discriminative ability, and it had a significantly better ability to predict the BCSS than the AJCC 7^th edition criteria (P < 0.001). The multivariate prognostic analysis showed that the new pathological prognostic staging was an independent prognostic factor affecting the BCSS. The BCSS worsened with an increase in the stage. The PMRT did not affect the BCSS regardless of the pathological prognostic stage. Similar trends were found using the competing-risks regression model.

Conclusions

The 8^th AJCC breast cancer pathological prognostic staging system downstaged 84.4% of patients with T1-2N1micM0 disease and the survival outcome prediction with this staging system was more accurate than the AJCC 7^th edition system. Our study does not support using the prognostic stage as a guideline to escalate of PMRT.

Negative lymph node count is an independent prognostic factor for female patients with node positive breast cancer

Background

Negative lymph node (NLN) count has been reported to associate with the prognosis of various cancers. This study aims to reveal the prognostic value of NLN count in breast cancer.

Methods

Clinical characteristics of patients were collected from the Surveillance, Epidemiology, and End Results (SEER) database. The X-tile program was used to determine the optimal cutoffs for NLN count. Univariate and multivariate analysis were used to assess the risk factors for breast cancer-specific survival (BCSS).

Results

The X-tile program identified that cutoff value of 2 and 10 could divide the patients into high, middle and low risk subgroups. According to multivariate analysis, patients with NLN count ≤1, over 60 years old, being black, higher tumor grade, higher T or N stage, negative hormone receptor, no radiotherapy or no chemotherapy would more likely suffer poor survival outcome. Subgroup analysis showed that NLN count could still predict survival independently.

Conclusions

NLN count is a potentially effective predictor of breast cancer and is a good supplement for N stage and TNM stage. Combining NLN count with other prognostic factors will be a better predictor for the survival of breast cancer patients.

Role of Sentinel Lymph Node Biopsy in Microinvasive Breast Cancer

BACKGROUND

Microinvasive ductal carcinoma (DCISM), defined as DCIS with a focus of invasive carcinoma ≤ 1 mm, can be managed similarly to pure DCIS; however, management of the axilla in DCISM has been a subject of debate. Reports in the literature differ on the utility and necessity of sentinel lymph node biopsy (SLNB) for DCISM. The aim of the present study was to identify risk factors for nodal disease in patients with DCISM, which can help develop a selective approach to SLNB in this patient population.

METHODS

The National Cancer Database was used to select patients with DCISM (pT1mi), diagnosed from 2012 to 2015, who underwent SLNB. Multivariable regression analysis was performed to determine associations between sentinel lymph node metastasis and relevant clinical variables.

RESULTS

Our cohort comprised of 2609 patients with pT1mi who underwent SLNB. Of these, 76 (2.9%) were found to have sentinel lymph node metastases on final pathology. Low/intermediate grade tumors were associated with decreased SLN metastasis (OR 0.50, CI 0.28-0.92). Age and receptor status of the tumor did not have a clear association in predicting SLN metastases.

CONCLUSIONS

The rate of sentinel node metastases in DCISM is low at only 2.9% in this national study. Tumor grade was identified as influencing the risk of SLN metastases. This information can factor into shared decision-making for SLNB in patients with DCISM.

Impact of 21-Gene Recurrence Score on Chemotherapy Decision in Invasive Ductal Carcinoma of Breast with Nodal Micrometastases

Purpose

The purpose of this study was to investigate the effect of 21-gene recurrence score (RS) on predicting prognosis and chemotherapy decision in node micrometastases (N1mi) breast invasive ductal carcinoma (IDC).

Methods

Patients with stage T1-2N1mi and estrogen receptor-positive IDC diagnosed between 2004 and 2015 were included. The associations of 21-gene RS with breast cancer-specific survival (BCSS), chemotherapy decision, and benefit of chemotherapy were analyzed.

Results

We identified 4,758 patients including 1,403 patients (29.5%) treated with adjuvant chemotherapy. In the traditional RS cutoffs, 2,831 (59.5%), 1,634 (34.3%), and 293 (6.2%) patients were in the low-, intermediate-, and high-risk RS groups, respectively. In 3,853 patients with human epidermal growth factor receptor-2 (HER2) status available, most patients were HER2-negative disease (98.3%). A higher RS was independently related to chemotherapy receipt, and 14.0%, 47.7%, and 77.8% of patients in the low-, intermediate-, and high-risk RS groups received chemotherapy, respectively. The multivariate analysis indicated that a higher RS was related to worse BCSS (p < 0.001). The 5-year BCSS rates were 99.3%, 97.4%, and 91.9% in patients with low-, intermediate-, and high-risk RS groups, respectively (p < 0.001). However, chemotherapy receipt did not correlate with better BCSS in low-, intermediate-, or high-risk RS groups. There were similar trends using Trial Assigning Individualized Options for Treatment RS cutoffs.

Conclusion

The 21-gene RS does predict outcome and impact on chemotherapy decision of N1mi breast IDC. Large cohort and long-term outcomes studies are needed to identify the effects of chemotherapy in N1mi patients by different 21-gene RS groups.

Impact of Micrometastatic Axillary Nodes on Survival of Breast Cancer Patients with Tumors ≤2 cm

BACKGROUND

This study investigated the impact of pN1mi disease on the survival of T1 breast cancer patients and examined the clinical usefulness of the online PREDICT tool and updated staging system.

METHODS

The node stages of 2344 patients were divided into pN0, pN1mi, and pN1a. Clinicopathological parameters and survival outcomes were retrospectively analyzed. Data for 111 micrometastatic diseases were applied to the PREDICT version 2.0 and re-classified using the 8th edition of the cancer staging manual.

RESULTS

Univariable analyses demonstrated worse disease-free and overall survival rates for patients with node-positive cancer; however, the significance was not maintained in multivariable analyses. Chemotherapy improved outcomes in patients with node-positive and non-luminal A-like subtype cancers. The PREDICT tool demonstrated good performance when estimating the 5-year overall survival for pN1mi disease (area under the receiver operating characteristic curve, 0.834). According to the updated staging system, 74% of cases were down-staged to IA, and clearly splitting survival curves were identified.

CONCLUSION

pN1mi disease alone did not adversely affect survival outcomes. Biologic and treatment factors determined outcomes in cases of small-volume node micrometastasis. The PREDICT tool or new staging classification could help predict the survival of patients with micrometastatic sentinel nodes.

Prognostic impact and possible pathogenesis of lymph node metastasis in ductal carcinoma in situ of the breast

PURPOSE

Ductal carcinoma in situ (DCIS)-preinvasive breast cancer-with lymph node metastasis can clinically be treated as different stages: occult invasive cancer with true metastasis (T1N1) or pure DCIS with iatrogenic dissemination (TisN0). In this retrospective cohort study, we aimed to elucidate the prognostic impact and possible pathogenesis of nodal metastasis in DCIS to improve clinical management.

METHODS

Subjects were comprised of 427 patients with routine postoperative diagnosis of DCIS who underwent sentinel node (SN) biopsy using molecular whole-lymph-node analysis. Clinicopathological characteristics and prognosis were compared between SN-positive and -negative patients. Primary tumour tissues of SN-positive patients were exhaustively step-sectioned to detect occult invasions, and predictive factors for occult invasion were investigated. Median follow-up time was 73.6 months.

RESULTS

Of the 427 patients, 19 (4.4%) were SN-positive and 408 (95.6%) were SN-negative. More SN-positive patients received adjuvant systemic therapy than SN-negative patients (84.2% vs. 5.4%). Seven-year distant disease-free survivals were favourable for both cohorts (SN-positive, 100%; SN-negative, 99.7%). By examining 1421 slides, occult invasion was identified in 9 (47.4%) of the 19 SN-positive patients. Tumour burdens in SN and incidence of non-SN metastasis were similar between patients with and without occult invasion, and no predictive factor for occult invasion was found.

CONCLUSIONS

Node-positive DCIS has favourable prognosis with adjuvant systemic therapy. Half of the cases may be occult invasive cancer with true metastasis. In practical settings, clinicians may have to treat these tumours as node-positive small invasive cancers because it is difficult to predict the pathogenesis without exhaustive primary tumour sectioning.

Sentinel Lymph Nodes in Classic Invasive Lobular Carcinoma of the Breast: Cytokeratin Immunostain Ensures Detection, and Precise Determination of Extent, of Involvement

The assessment of sentinel lymph nodes (SLN) on hematoxylin and eosin (H&E)-stained sections in cases of classic type of invasive lobular carcinoma (cILC) is considered unreliable, particularly in cases with minimal involvement, that is by either isolated tumor cells (pN0i+) or micrometastases (pN1mi). Although the impact of minimal SLN involvement has been shown to be insignificant in most clinical trials (even though cILC was either under-represented or not separated in the respective cohorts), the results of MIRROR trial did emphasize the need for additional therapy in cases with minimally involved SLN to ensure improved disease-free survival. We sought to study the role of cytokeratin immunohistochemistry (CK-IHC) in evaluating SLN in cILC. A total of 582 cILC cases with SLN diagnosed over a 12-year period (2005 to 2016) were reviewed. In all, 394/582 (68%) cases had H&E(-)/CK(-) SLN. In total, 188/582 (32%) cases showed some degree of SLN involvement of which 143/582 (25%) cases had readily identifiable SLN involvement on H&E slides. Overall, 45/582 (7.7%) cases had H&E(-)/CK(+) SLN. The following data relate to the latter subset of 45 cases. Mean age of patients: 61 y (range: 32 to 86 y); right: 24 (53%), left: 21 (47%); multifocal and/or multicentric: 22 (49%); mean size: 2.0 cm (range: 0.25 to 4.4 cm); mean number of SLN: 2.5; mean number of involved SLN: 1.2; and cases with prior needle core or excisional biopsy: 45 (100%). CK(+) cells were identified in isolation or in loose clusters, either in subcapsular sinuses or nodal cortex or both. Overall, 30/45 (67%) showed ≤200 CK(+) cells (ie, pN0i+), and 15/45 (33%) showed >200 CK(+) cells (ie, pN1mi). In total, 15/45 (33%) cases underwent axillary lymph node dissection, of which 4/45 (9%) cases were positive. cILC recurred in 3/45 (7%) cases. On statistical analyses, the number of CK(+) cells (≤/>200) did not correlate with either axillary lymph node-positivity or with recurrence. Number of CK(+) cells (≤/>200) readily distinguished pN0i+ from pN1mi based on AJCC's numerical criteria. CK(+) cells could be quantified in linear terms (ie, AJCC's size criteria of pN0i+ and pN1mi was applicable) in only 2 cases. On the basis of these findings, the use of CK-IHC staining should be considered for SLN in cases of cILC to ensure detection, and precise determination of extent, of involvement; however, the prognostic significance of this procedure would have to await results of additional studies with long-term follow-up.