Proposed Section Structure
This article is organized to match the clinical and scientific questions raised by the study: clinical context and unmet need in occult breast cancer; study design and methods; key efficacy findings including pathologic complete response by subtype; diagnostic performance of clipped-node pathology for residual axillary burden; clinical interpretation in relation to axillary de-escalation; limitations and implications for practice and research; and citation, funding, and trial registration details.
Highlights
Occult breast cancer remains a rare but clinically important scenario in which current guidelines generally favor axillary lymph node dissection, despite growing interest in de-escalated axillary surgery after neoadjuvant systemic therapy.
In this cohort of 85 patients with occult breast cancer treated with neoadjuvant systemic therapy, pathologic complete response in the axilla varied strongly by subtype: 33.3% in hormone receptor-positive/HER2-negative disease, 83.3% in HER2-positive disease, and 77.4% in triple-negative disease.
Among patients with a clipped biopsy-proven positive axillary node, post-treatment pathology of the clipped node showed high specificity for residual axillary disease burden, with the most reassuring performance observed in patients presenting with cN1 or cN2 disease.
The findings support studying limited axillary surgery anchored to clipped-node retrieval as a potential staging strategy in selected patients with occult breast cancer after systemic therapy, rather than automatic completion axillary dissection for all.
Background
Occult breast cancer (OBC) is an uncommon presentation of breast malignancy in which metastatic axillary lymphadenopathy is identified, but no primary breast lesion is detectable on standard clinical, radiographic, and pathologic evaluation. This presentation creates a management challenge because treatment decisions must be made without a visible breast primary, while still addressing regional nodal disease that is often biopsy proven at diagnosis.
Historically, axillary lymph node dissection (ALND) has been the default surgical approach for OBC. That practice reflects both the rarity of the disease and the limited representation of OBC in prospective trials that established less extensive axillary surgery in patients with non-occult breast cancer. In contemporary breast oncology, however, neoadjuvant systemic therapy (NST) has become a major platform for downstaging nodal disease and potentially reducing surgical morbidity. This has been especially relevant in HER2-positive and triple-negative breast cancer, where pathologic complete response (pCR) rates are often substantial.
The central clinical question is whether patients with OBC can safely benefit from the same trend toward axillary de-escalation seen in non-occult breast cancer. One practical strategy is targeted removal of the pre-treatment biopsy-proven positive axillary node marked by a clip at diagnosis. If pathology in the clipped node reliably reflects the status of the remaining axilla after NST, surgeons may be able to use limited axillary surgery to stage selected patients while avoiding the lymphedema, shoulder dysfunction, sensory symptoms, and quality-of-life burden associated with full ALND.
Study Design and Methods
Lattimore and colleagues evaluated this question using data from an observational cohort of patients diagnosed with occult breast cancer between 2010 and 2025. The analysis included 85 patients with OBC who received neoadjuvant systemic therapy followed by surgery. The investigators aimed to estimate two clinically relevant outcomes: first, the probability of pCR after NST; and second, the diagnostic performance of pathology from the pre-treatment biopsy-positive clipped axillary lymph node in identifying residual axillary disease burden after NST.
The study population was stratified by biologic subtype, an important design feature because response to NST differs markedly by hormone receptor and HER2 status. Reported subgroups included hormone receptor-positive/HER2-negative, HER2-positive, and hormone receptor-negative/HER2-negative disease.
A second key feature was the use of clip placement in the biopsy-proven positive node at diagnosis. Of the 85 patients, 46 patients, or 54.1%, had a clip placed in the involved axillary node before treatment. This enabled post-NST surgical retrieval and pathologic evaluation of the exact node known to contain metastasis at presentation.
The main diagnostic metrics reported were specificity and false-negative rate (FNR) of clipped-node pathology for assessing residual axillary disease burden. These measures are highly relevant in surgical decision-making. High specificity means that a positive clipped-node result strongly suggests ongoing residual disease in the axilla. A low false-negative rate is particularly important if surgeons are considering omitting ALND when the clipped node appears cleared after NST.
Key Findings
Pathologic complete response rates varied sharply by tumor subtype
The study found that pCR after neoadjuvant systemic therapy was strongly associated with biologic subtype. Among 36 patients with hormone receptor-positive/HER2-negative disease, 12 achieved pCR, for a rate of 33.3%. This lower response rate is directionally consistent with broader breast cancer experience, where endocrine-responsive, lower-proliferation tumors often demonstrate less dramatic pathologic eradication after chemotherapy-based NST.
In contrast, patients with HER2-positive OBC had a pCR rate of 83.3%, with 15 of 18 patients achieving pCR. Likewise, among 31 patients with hormone receptor-negative/HER2-negative disease, 24 achieved pCR, for a rate of 77.4%. These are strikingly high rates and align with the current understanding that HER2-positive disease treated with anti-HER2 therapy and triple-negative disease treated with modern systemic regimens are often highly responsive in the neoadjuvant setting.
Clinically, these data matter because they suggest that OBC behaves in a subtype-dependent fashion similar to non-occult breast cancer. That supports using tumor biology, not just disease presentation, when considering the feasibility of less extensive surgery after NST.
Clipped-node pathology showed high specificity for residual axillary burden
Among all OBC patients with a clipped biopsy-proven positive node, post-treatment pathologic assessment of the clipped node had a specificity of 88.6%, with a 95% confidence interval of 75.1% to 96.0%. This indicates that when the clipped node remained pathologically involved after NST, it was usually a reliable signal that residual disease persisted elsewhere in the axilla.
The overall false-negative rate was 13.3%, with a wide 95% confidence interval of 2.9% to 36.3%. The wide interval reflects the modest sample size and underscores caution in overinterpreting the point estimate. Even so, the result is clinically meaningful because it suggests that, in many patients, the clipped node may serve as a reasonable sentinel of the broader nodal response to therapy.
Performance appeared strongest in cN1 and cN2 disease
The most practice-relevant subgroup finding was in patients with cN1 or cN2 disease. In this subset, clipped-node pathology had a specificity of 86.2%, with a 95% confidence interval of 70.5% to 95.2%, and a false-negative rate of 0%, with a 95% confidence interval of 0% to 21.7%.
The point estimate of a 0% false-negative rate is encouraging and suggests that clipped-node retrieval may be particularly dependable in patients with limited to moderate nodal burden at presentation. However, the upper bound of the confidence interval remains over 20%, reminding readers that the sample is still too small to conclude definitively that the true false-negative rate is near zero. Still, this subgroup finding provides the clearest rationale for considering limited axillary surgery in selected OBC patients rather than mandating ALND for all.
Clinical Interpretation
This study addresses an important evidence gap. OBC is rare, and management has often been extrapolated from more common forms of node-positive breast cancer. Yet de-escalation strategies proven or increasingly adopted in non-occult disease cannot automatically be assumed to apply to OBC. The current analysis suggests that such caution is justified but should not prevent thoughtful innovation.
The first clinically relevant message is that substantial nodal eradication after NST is common in biologically favorable subtypes, especially HER2-positive and triple-negative OBC. If a large proportion of these patients achieve pCR, routine ALND may expose many patients to morbidity without clear therapeutic benefit.
The second message is more technical but arguably more important: the pathologic status of the clipped node appears to track the residual burden in the rest of the axilla. This concept mirrors the rationale behind targeted axillary dissection in non-occult breast cancer, where removal of the known positive clipped node, often along with sentinel nodes, improves staging accuracy after NST compared with sentinel node surgery alone.
From a surgical standpoint, the findings support a selective pathway. In patients with OBC who present with cN1 or cN2 disease, undergo successful clip placement in the biopsy-proven positive node, and receive effective neoadjuvant therapy, retrieval and pathologic assessment of the clipped node may provide a basis for limited axillary staging. This does not mean ALND should be abandoned broadly. Rather, it suggests that automatic completion dissection in every patient with OBC may no longer be the only reasonable framework.
These results are especially relevant to multidisciplinary decision-making. Surgeons, medical oncologists, radiologists, and pathologists all contribute to successful implementation of a clipped-node strategy. Reliable clip placement, localization at surgery, accurate pathologic confirmation that the clipped node was removed, and careful interpretation of residual disease all become essential. In rare diseases such as OBC, the quality of this workflow may be as important as the procedure itself.
How These Findings Fit With Existing Evidence and Guidelines
Current international and specialty guidelines have generally recommended ALND for OBC with axillary metastasis, largely because direct evidence supporting less extensive surgery has been sparse. At the same time, breast oncology has moved steadily toward axillary minimization in non-occult disease, based on trials of sentinel lymph node surgery, neoadjuvant downstaging, and targeted axillary dissection.
Although this study does not by itself change guidelines, it provides disease-specific evidence that OBC may be suitable for a more nuanced approach. The biologic pCR rates reported here mirror patterns from conventional breast cancer populations: higher response in HER2-positive and triple-negative disease, lower response in hormone receptor-positive/HER2-negative tumors. That consistency strengthens the biological plausibility of applying response-adapted axillary strategies in OBC.
Prior work from major breast centers has shown that targeted axillary dissection can lower false-negative rates after NST in node-positive breast cancer by ensuring removal of the clipped metastatic node. The current study extends that logic into OBC, where the axilla is not just a site of regional spread but often the only detectable site of disease at diagnosis.
Limitations
Several limitations should temper interpretation. First, the study is observational, which introduces risks of selection bias, treatment heterogeneity, and center-specific practice effects. Second, the sample size is necessarily limited because OBC is rare, and only 46 patients had a clipped node available for the key diagnostic analysis. This is reflected in the wide confidence intervals, especially for the false-negative rate.
Third, clip placement was not universal. Slightly less than 55% of patients had a clip placed in the biopsy-proven positive node. That means the most relevant conclusions apply to a selected subset in whom targeted localization was feasible and performed. Fourth, the abstract does not provide granular details regarding imaging workup, exact surgical techniques, pathologic processing, systemic therapy regimens, or long-term oncologic outcomes such as locoregional recurrence and survival. Those endpoints are crucial before limited axillary surgery can be considered fully validated.
Finally, the study focuses on the relationship between clipped-node pathology and residual axillary disease burden, not on whether omitting ALND based on these findings produces equivalent long-term outcomes. Diagnostic performance is a necessary first step, but oncologic safety remains the ultimate question.
Implications for Practice
For clinicians treating OBC today, the study supports several practical considerations. Biopsy-proven metastatic axillary nodes should be clipped whenever possible at diagnosis if NST is planned. That single procedural step may create a pathway to more precise surgical staging later.
Patients with HER2-positive or triple-negative OBC appear especially likely to benefit from response-adapted planning because their pCR rates after NST are high. In these subtypes, the balance between oncologic control and surgical morbidity may increasingly favor selective de-escalation in expert centers.
Patients with hormone receptor-positive/HER2-negative disease had a markedly lower pCR rate of 33.3%, which suggests greater caution. In that subgroup, the prior probability of residual nodal disease is higher, so the threshold for ALND may remain lower until more robust evidence becomes available.
For now, the most defensible interpretation is that limited axillary surgery anchored in clipped-node retrieval should be considered investigational but clinically promising in selected OBC patients, particularly those with cN1 or cN2 disease and good response to NST. Decision-making should remain multidisciplinary and individualized.
Future Research Priorities
Next steps should include multicenter validation studies with standardized protocols for clip placement, localization, surgical retrieval, and pathology review. Prospective registries may be more feasible than randomized trials in this rare disease, although cooperative group efforts would be valuable.
Researchers should also report longer-term outcomes, including axillary recurrence, disease-free survival, overall survival, lymphedema rates, and patient-reported quality of life. An ideal future framework would integrate baseline nodal stage, biologic subtype, radiographic response, and clipped-node pathology to define which OBC patients can safely avoid ALND.
Another important question is whether clipped-node retrieval alone is sufficient or whether it should be combined with sentinel node surgery, as in targeted axillary dissection protocols used for non-occult breast cancer. Comparative data will be needed before a standard de-escalated approach can be recommended.
Conclusion
This observational study provides rare and clinically useful data in occult breast cancer, a setting where evidence is often limited and surgical practice has remained conservative. The investigators show that pCR after neoadjuvant systemic therapy is common in HER2-positive and triple-negative OBC and less frequent in hormone receptor-positive/HER2-negative disease. More importantly, pathology of the pre-treatment biopsy-proven clipped axillary node appears to reflect the residual disease burden in the remaining axilla, with encouraging diagnostic performance, particularly in patients with cN1 or cN2 disease.
The findings do not eliminate the need for caution, but they do challenge the assumption that all patients with OBC require routine axillary lymph node dissection after NST. In expert multidisciplinary settings, limited axillary surgery anchored in clipped-node retrieval deserves serious consideration as a staging strategy for selected patients. For a rare disease long managed by extrapolation, this study moves the field a meaningful step closer to evidence-based axillary de-escalation.
Funding and ClinicalTrials.gov
Funding information was not reported in the abstract provided. A ClinicalTrials.gov registration number was not reported in the abstract provided.
References
1. Lattimore CM, Johnson HM, Kuerer HM, Caudle AS, Giordano SH, Singh P, Hunt KK, Huo L, Wanis KN. Clipped Node Pathology as a Guide for Limited Axillary Surgery in Occult Breast Cancer. Ann Surg. 2026 May 15. PMID: 42135887.
2. National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Breast Cancer. Current publicly available guideline framework supports multidisciplinary management of occult breast cancer and remains an important benchmark for axillary decision-making.
3. Caudle AS, Yang WT, Krishnamurthy S, et al. Improved axillary evaluation following neoadjuvant therapy for patients with node-positive breast cancer using selective evaluation of clipped nodes: implementation of targeted axillary dissection. J Clin Oncol. 2016;34(10):1072-1078.
4. Boughey JC, Ballman KV, Le-Petross HT, et al. Identification and resection of clipped node decreases the false-negative rate of sentinel lymph node surgery in patients presenting with node-positive breast cancer who receive neoadjuvant chemotherapy: results from ACOSOG Z1071. Ann Surg. 2016;263(4):802-807.
5. Kuerer HM, Rauch GM, Krishnamurthy S, et al. A clinical feasibility trial for identification of exceptional responders in whom breast cancer surgery can be eliminated following neoadjuvant systemic therapy. Ann Surg. 2018;267(5):946-951.