Controversies in locoregional management of breast cancer with low volume pN0(i+) and pN1mi nodal disease

ABSTRACT

Introduction: The pathologic status of the axillary lymph nodes is an important prognostic factor in patients with breast cancer. With the transition from axillary lymph node dissection (ALND) to sentinel lymph node biopsy (SLNB) for patients with clinically node negative breast cancer, there has been an increase in detection of pN0(i+) breast cancer with isolated tumor cells and pN1mi disease with micrometastatic nodal involvement. The prognostic impact of small volume nodal involvement and the role of locoregional radiotherapy, especially in the era of modern systemic therapy, are unclear.

Areas covered: This review examines contemporary data evaluating the prognostic impact of pN0(i+) and pN1mi breast cancer on locoregional recurrence and survival outcomes, then discusses controversies related to the use of adjuvant locoregional radiation therapy in the presence of low volume nodal disease. Relevant papers were identified by searching multiple engines for articles published since 2000.

Expert opinion: Sentinel lymph node biopsy without completion ALND is a standard surgical option for patients with pN0(i+) and pN1mi disease. The available evidence does not support routine use of adjuvant locoregional radiation therapy in patients with pN0i+ or pN1mi disease, but locoregional radiotherapy should be considered in the presence of concomitant high-risk features and patient factors.

KEYWORDS:

• Breast cancer
• sentinel lymph node biopsy
• pN0(i+)
• isolated tumor cells
• pN1mi
• nodal micrometastasis
• locoregional recurrence
• survival
• radiotherapy

Article highlights

• Surgical evaluation of the axilla has shifted from axillary lymph node dissection (ALND) to sentinel lymph node biopsy (SLNB) in patients with a clinically negative axilla.

• The evidence that SLNB alone is non-inferior to ALND is strongest in the setting of breast-conserving surgery with adjuvant locoregional radiotherapy.

• Modern pathologic SLN assessment techniques have led to increased detection of pN0(i+) with isolated tumor cells and pN1mi with micrometastatic nodal deposits.

• Patients with pN0i+ disease appear to have locoregional recurrence (LRR) and survival prognoses similar to patients with node-negative disease.

• Patients with pN1mi disease appear to have LRR and survival outcomes intermediate between node-negative and macroscopic node-positive disease.

• Adjuvant locoregional radiation therapy should not be routinely used in patients with pN0i+ or pN1mi disease but may be considered in the presence of concomitant high-risk features such as young age, large primary tumors, lymphovascular invasion, grade 3 histology, positive margin, and ER-negative disease.

• Adjuvant treatment decisions should be individualized within a multidisciplinary context, taking into consideration patient and disease-specific factors to estimate the risks of non-SLN involvement and locoregional recurrence.

• Patients with small volume nodal disease who are offered adjuvant radiation should be carefully informed of the potential benefits balanced against potential toxicities of treatment.

• Prospective randomized trials are needed to define the role of adjuvant locoregional radiation therapy in patients with pN0(i+) and pN1mi breast cancer.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships.

Additional information

Funding

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