Moderately hypofractionated regional nodal irradiation had 6.4% three-year lymphedema

KEY POINTS

• This prospective single-institution trial included 52 women with non-metastatic node-positive or high-risk node-negative breast cancer requiring regional nodal irradiation. 41 patients underwent sentinel lymph node biopsy and 11 underwent axillary lymph node dissection.
• All patients received 42.56 Gy in 16 daily fractions to the breast or chest wall and indicated regional lymphatics, including axillary, supraclavicular and internal mammary nodes. A sequential 10-12.5 Gy boost in 4-5 fractions was permitted to the tumor bed or mastectomy scar.
• The primary endpoint, cumulative clinically significant upper-extremity lymphedema at 3 years, was 6.4% overall. Rates were 5.7% after sentinel lymph node biopsy versus 9.1% after axillary dissection, with no significant difference (p=0.62).
• Lymphedema appeared at a median of 7 months, and importantly, no additional cases occurred through 60 months. Every detected case showed forearm positivity using the standard two-point measurement method.
• More extensive circumferential measurements taken every 10 cm did not detect lymphedema earlier and identified no additional cases compared with standard arm and forearm measurements, suggesting little added value from the more complex protocol.
• Late toxicity was predominantly grade 1-2, with no grade ≥3 late adverse events. Among 41 breast-conserving patients, cosmesis was rated excellent in 70.7%, good in 24.4%, and fair in 4.9%, with no poor ratings.
• Disease control was also reassuring: no locoregional recurrences occurred, while distant metastasis-free and progression-free survival were 93.4% at 36 months and 87.9% at 60 months. Overall survival was 97.2% at both 36 and 60 months.

CLINICAL TAKEAWAY

SOURCE

Practical Radiation Oncology