Boost Dose and Fractionation for Gross Supraclavicular Lymph Node in TNBC
For a gross supraclavicular lymph node in triple-negative breast cancer, deliver at least 66 Gy EQD2 (equivalent to approximately 66 Gy in 2 Gy fractions or 60 Gy in 15 fractions using hypofractionation) to the involved node region. 1
Dose Recommendation Based on Disease Burden
The most recent ASTRO-ASCO-SSO guideline (2025) provides explicit dosing guidance for undissected nodal basins with gross disease 1:
- Microscopic disease: 60 Gy EQD2
- Gross or residual disease: At least 66 Gy EQD2
Since you are dealing with a gross supraclavicular node, the higher dose threshold of 66 Gy EQD2 applies.
Fractionation Options
Conventional Fractionation
- 66 Gy in 33 fractions (2 Gy per fraction) is the traditional approach referenced in the guideline 1
Hypofractionated Approach
- If using moderate hypofractionation (2.67 Gy per fraction), this translates to approximately 60 Gy in 22-23 fractions to achieve equivalent EQD2
- The guideline notes that early reports suggest comparable outcomes with ultrahypofractionation to nodal regions, though data remain limited 1
Evidence Quality and Limitations
Important caveat: The guideline explicitly acknowledges that no randomized studies have examined boost doses to gross disease in undissected nodal basins like the supraclavicular fossa 1. The recommendations are based on:
- Institutional retrospective analyses showing that boosts to involved supraclavicular nodes can be delivered safely and may improve local control 1
- Recognition that supraclavicular involvement is a poor prognostic factor 1
- Small sample sizes limiting the strength of evidence 1
TNBC-Specific Considerations
While TNBC has more aggressive biology and higher locoregional recurrence rates compared to luminal subtypes 2, 3, the subtype itself should not alter standard radiation dose recommendations 3. The dose is determined by the presence of gross disease, not the molecular subtype.
Research data from patients with supraclavicular involvement (including TNBC) showed that doses ≥54 Gy to the supraclavicular region did not improve disease-free survival compared to standard doses 4, but this study used neoadjuvant chemotherapy and the median dose was only 50.4 Gy—below the guideline-recommended threshold for gross disease.
Technical Delivery
- Use CT-based volumetric planning with appropriate contouring of the gross node and organs at risk 1
- Consider IMRT/VMAT techniques to optimize dose distribution and minimize toxicity to surrounding structures (lung, brachial plexus, thyroid) 1
- Ensure adequate coverage while keeping doses to organs at risk as low as reasonably achievable 1