Lymph nodal radiotherapy in breast cancer: what are the unresolved issues?

ABSTRACT

Introduction: Sentinel lymph node biopsy (SLNB) is the gold standard in invasive breast cancer. Axillary dissection (ALND) is controversial in some presentations.

Areas covered: Key questions were formulated and explored focused on four different scenarios in adjuvant axillary radiation management in early and locally advanced breast cancer. Answers to these questions were searched in MEDLINE, PubMed from June 1946 to August 2020. Clinical trials, retrospective studies, international guidelines, meta-analysis, and reviews were explored.

Expert opinion: Analysis according to biological disease characteristics is necessary to establish the impact of ALND avoidance in unexpectedly positive SLNB (pN1) in cN0 patients. A low-risk probability of axillary recurrence was observed if axillary radiotherapy (ART) or ALND were offered without impact on outcomes. Adjuvant RNI in pT1-3 pN1 treated with mastectomy or BCS should be proposed in unfavorable disease and risk factors. In ycN0 after NACT, SLNB can be offered in selected cases or ALND should be performed. After SLNB post-NACT (ypN1), ALND and adjuvant radiotherapy are mandatory.

KEYWORDS:

• Breast cancer
• radiotherapy
• sentinel lymph node biopsy
• axillary dissection
• neoadjuvant chemotherapy

Article highlights

• Sentinel lymph node biopsy is the gold standard axillary approach in invasive breast cancer. Axillary dissection is under debate in some disease presentations

• Axillary lymph nodes dissection could be avoided in selected pN0i+/pN1mic patients. There are not sufficient data with high level of evidence, particularly for patients treated with mastectomy

• Additional sub-analysis according to biological disease characteristics is necessary in order to establish the impact of ALND avoidance or other adjuvant approaches in unexpectedly positive SLNB (pN1) in cN0 patients

• Axillary radiotherapy instead of dissection in positive sentinel node biopsy has been explored in phase III clinical trials. An equally low-risk probability of axillary recurrence was observed if radiotherapy or dissection were offered without impact on outcomes

• Adjuvant regional nodal irradiation in pT1-pT3 pN1a patients treated with mastectomy or breast conservative therapy should be proposed in unfavorable disease and risk factors. Multidisciplinary discussion is established as mandatory so as to personalize adjuvant oncological treatment and reduce the probability of late side effects

• Sentinel lymph node biopsy post-preoperative systemic therapy has an important clinical benefit toward axillary lymph nodes dissection. In ycN0 after primary chemotherapy, sentinel lymph node biopsy can be offered in selected cases otherwise axillary lymph nodes dissection should be performed. After sentinel lymph node biopsy post primary chemotherapy (ypN1), axillary lymph node dissection and adjuvant radiotherapy are mandatory

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 to disclose.