Axillary Surgery Versus Radiation as Treatment of Regional Nodes: AMAROS Trial and Beyond

Axillary Surgery Versus Radiation as Treatment of Regional Nodes: AMAROS Trial and Beyond

Amanda Amin

Melissa Mitchell

Indications for Axillary Dissection Versus Targeted Radiation to the Axilla

Surgery First

Lumpectomy patients, cT1-2N0, ≤2 nodes found on SLNB, no gross ECE: In clinically node-negative patients with T1–2 tumors undergoing upfront surgery with lumpectomy and planned for whole breast radiation, sentinel node biopsy is sufficient, as described in the previous section. The radiation oncologist should ensure that the entire level I and II axilla is encompassed in the radiation tangent portal, as shown in Figure 29-1. The decision for extended radiation to include the supraclavicular and internal mammary nodes, RNI, should be made based on careful review of patient and tumor characteristics, such as patient age, tumor size, and tumor biology, as described in the cases below.

Lumpectomy patients, cT2N0, ê 3 nodes found on SLNB or gross ECE: These patients were not included on the Z0011 trial, and only 5% of patients on AMAROS and OTOASOR had ≥3 positive sentinel nodes. As these patients were not well represented in randomized trials of SLNB alone, the standard of care is to proceed with ALND in patients with >2 positive nodes or gross ECE. These patients should receive RNI in addition to whole breast radiotherapy.

Exploratory data exists for both ALND and SLNB alone in this population. A retrospective review at Memorial Sloan Kettering Cancer Center (MSKCC) suggests that patients with gross ECE or >2 positive nodes are very high risk for additional nodal disease (11). They changed their standard practice to routinely omit ALND in
patients who met strict criteria for eligibility for Z0011. However, patients with ≥3 positive lymph nodes, gross ECE, or matted adenopathy were still recommended for completion ALND. In patients meeting these exclusion criteria and recommended for ALND, 72% had additional positive nodes. With a median follow-up of 13 months, distant metastatic disease developed in 7% of the patients recommended for ALND, highlighting the competing distant disease risk in this population of patients with more aggressive tumor biology.

FIGURE 29-1 Radiation tangent field design for patients with a positive sentinel node not undergoing ALND. The Radiation Therapy Oncology Group breast cancer contouring atlas should be used to contour axillary levels I and II. A: A representative axial slice shows a contour of the level I and II axilla in purple, with lymphatic space contoured medial to the pectoralis minor and including the pectoralis minor. Using a standard tangent angle (yellow) may miss the posterior axilla. A steeper tangent angle (red) can improve coverage of the axilla target, while still sparing lung. B: Standard tangent fields encompass the breast alone with 1-cm superior and inferior margins on the breast tissue. C: Modified tangent fields are shown, with a raised superior border and posterior extension of the upper portion of the tangent field to include the axilla contour (shown in purple) in the radiation port. Dashed blue line depicts extension of standard tangents to the level of the humeral head “high tangent” and how a high tangent would encompass less of the axilla than 3D conformal radiation targeting this area.

In support of omitting ALND, a SEER analysis was performed to assess outcomes for pT1–T2 patients with ≥3 positive lymph nodes found on SLNB (12). There was no difference in OS in patients undergoing completion ALND versus SLNB alone when adjusted for age, use of radiation, tumor size, hormone status, or tumor grade. As the data to support this practice is limited, omission of ALND in patients with three positive nodes or gross ECE is cautionary outside of a clinical trial, and should only be considered in the setting of low disease burden, such as low nomogram scores (13).

Lumpectomy patients, cT3N0: While OTOASOR included some T3 patients, they represented a very small portion of the population. As AMAROS and Z0011 did not include cT3 tumors, the standard of care for these patients is ALND. These patients will all require adjuvant radiation therapy to the breast and RNI.

Recommendations for ALND in this group stem from a high risk of additional nodal disease in studies of SLNB followed by completion ALND for T3 patients, in the range of 57% to 80%. Routine substitution of radiation for ALND in T3 patients should not be performed off trial until additional data is obtained. Cautious use can be considered in patients who are low risk for additional disease based on nomograms (13). All of these patients will be at high risk for distant disease, thus systemic therapy should be optimized.

Mastectomy patients, pT1–2N1mi: Z0011 excluded patients undergoing mastectomy as the primary breast surgery, and therefore this trial is not applicable to patients proceeding with mastectomy. Although both IBCSG 23-01 and AATRM included patients proceeding with mastectomy, this population was a small minority of the entire cohort (9%). Furthermore, only pN1mi patients were included (6,7). Patients with pN0(i+) or pN1mi disease may be considered for SLNB alone, even if PMRT is not planned, in the setting of biologically favorable disease. Patients with highly unfavorable features, such as young age, unfavorable tumor biology, large primary tumor, should be treated similar to patients with macrometastatic disease (pN1).

Further data to support this practice includes a retrospective study from MSKCC that reviewed outcomes of node-positive patients undergoing mastectomy and SLNB alone, no radiation (14). The majority of mastectomy patients in this study had isolated tumor cells (ITCs) at SLNB (54%, pN0[i+]) and 37% had pN1mi disease. Only 9% had pN1 macrometastatic disease. Almost all of the patients (99%) were pT1–2. Patients included in this study had low risk of additional axillary nodal involvement, with a median risk of nonsentinel axillary nodal metastasis of 9% per the MSKCC nomogram. None of the patients with pN0(i+) disease developed an axillary recurrence. Excluding those with ITCs, the 4-year local and regional recurrence rates in this study were very low for node-positive mastectomy patients with pN1mi and pN1 disease (1.2% and 2.5%, respectively).

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Aug 25, 2021 | Posted by in Aesthetic plastic surgery | Comments Off on Axillary Surgery Versus Radiation as Treatment of Regional Nodes: AMAROS Trial and Beyond
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