Axillary Radiation (AR) Instead of Undergoing an Axillary Dissection (ALND)?

• The European Organisation for Research and Treatment of Cancer (EORTC) 10981 After Mapping of the Axilla, Radiation or Surgery? (AMAROS) trial:
  • Randomized 4806:
    • Clinically node-negative
    • T1 to T2 tumors:
      • To completion axillary lymph node dissection (ALND) or axillary radiation (AR):
        • If they had positive nodes
    • Of the 1425 patients with positive sentinel nodes:
      • 744 had been randomly assigned to ALND
      • 681 to AR
    • Initially:
      • Patients with tumors 3 cm or smaller were eligible:
        • But the protocol was later modified to include:
          • Tumors up to 5 cm, multifocal tumors, or both
    • In the AR arm 21% of patients had T2 lesions
    • There were no age limits for eligibility:
      • Patients ranged from age 48 to 64 years
    • In the AR arm:
      • 42% of women were premenopausal
    • Patients who had either partial or total mastectomy were enrolled in the trial:
      • 18% of women had mastectomy
    • There was no limit on the number of positive nodes for the radiation arm:
      • But the majority of patients had 1 or 2 positive nodes
    • Crossover was allowed:
      • For patients with extensive axillary disease:
        • From the radiation arm to the dissection arm
      • Patients in the dissection arm who had 4 or more positive nodes:
        • Where allowed to have axillary radiation
        • Four percent of patients who stayed in the radiation arm had 3 positive nodes, and 1% had 4 or more positive nodes.
    • Importantly:
      • In the axillary dissection arm:
        • 25% of patients had an additional 1 to 3 positive nodes (in addition to the positive sentinel nodes) at dissection
        • 8% had 4 or more additional positive nodes
      • Since it was a randomized trial:
        • We can assume the same numbers were present in the radiation arm:
          • So these patients did not necessarily have low-volume axillary disease.
    • Axillary radiotherapy (RT) included:
      • The contents of all 3 levels of the axilla and the medial part of the supraclavicular fossa
      • The prescribed dose was 25 fractions of 2 Gy each
      • For patients in the AR arm who had mastectomy:
        • Radiation to the chest wall in addition to the axilla was optional but not mandatory
    • There were no significant differences:
      • In 5-year overall survival or disease-free survival between the two arms:
        • At 6.1 years of follow-up:
          • There was no significant difference:
            • In the rate of axillary failure:
              • 0.43% ALND vs 1.19% RT
        • At 5-year follow-up there was a significant difference:
          • In clinical signs of lymphedema between the groups:
            • 23% in ALND vs. 11% in AR:
              • There was greater than a 10% difference in arm size compared to the contralateral arm:
                • In 13% of the ALND arm and 5% of the AR arm
• The AMAROS study findings would suggest that axillary RT is an appropriate alternative to ALND in patients with a positive sentinel node:
  • However, the clinical characteristics of the AMAROS cohort are remarkably similar to the American College of Surgeons Oncology Group (ACOSOG) Z0011 cohort:
    • With 80% of AMAROS patients having:
      • A tumor less than 2 cm
    • 90% patients:
      • Receiving any systemic therapy
    • 95% of patients:
      • Having only 1 to 2 positive sentinel nodes
  • Patients in ACOSOG Z0011 treated with sentinel lymph node biopsy only demonstrated:
    • Similar 5-year rates of regional recurrence as the AMAROS patients receiving axillary RT:
      • 0.9% [ACOSOG Z0011] vs 1.2% [EORTC 10981 AMAROS axillary RT]):
        • Thus, while AMAROS indicates that sentinel node biopsy and nodal RT is an alternative to ALND:
          • It does not demonstrate that RT is necessary in all patients with a positive sentinel node:
            • Particularly in those treated with breast-conserving surgery
  • The decision to include axillary RT in patients with 1 to 2 positive sentinel nodes:
    • Should be tailored to the individual:
      • Taking into account other clinical factors which may place the patient at higher risk for locoregional recurrence

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