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Topics:
Breast Cancer • Radiation Oncology
What is an acceptable upper limit for ipsilateral lung V8 Gy when using the Fast Forward regimen with high tangents to cover limited axillary disease?
The FAST-Forward trial utilized a strict V8 Gy <15% constraint for whole breast irradiation. However, in clinical practice for patients with N1mi or limited nodal disease requiring high tangents (Level I/II coverage), meeting this constraint often compromises target coverage.
Is it clinically acceptable to accept a V8 Gy in the 20-25% range in this setting, given the low rates of pneumonitis in the trial, or is failure to meet V8 Gy <15% a strict indication to revert to moderate hypofractionation (40 Gy/15 fx)?
Answer from: Radiation Oncologist at Community Practice
I would say ipsilateral V8 is more for the ALARA principle and not based on risk of Pneumonitis, and thus would accept a higher number to cover low axillary if needed.
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Answer from: Radiation Oncologist at Academic Institution
The UK FAST-Forward nodal sub-study (covering axillary levels I-IV without IMN coverage) permitted an ipsilateral lung V30% of up to 25% and reported comparable rates of symptomatic lung fibrosis (2%) at 5 years for both the 40 Gy/15 Fx and 26 Gy/5 Fx schedules (Brunt et al., PMID 40379410).