Topics:
Breast Cancer • Radiation Oncology
When do you add a third field for IMPORT-LOW style partial breast irradiation?
The IMPORT-LOW and DBCG trials of 40 Gy in 15 fraction PBI utilized mini-tangents, which simplify planning but increase breast V40 Gy.
The paper by Thomsen et al., PMID 36265685 clearly shows that breast V40 Gy is correlated with induration.
When treating with IMPORT-LOW, when would you consider adding a 3rd field to reduce V40 Gy? I worry about increasing the risk of a secondary lung cancer, heart disease, etc. for an improvement in cosmesis.
Answer from: Radiation Oncologist at Community Practice
I don’t usually use the 3rd field and treat with min tangent with FIF to improve homogeneity.
If planning to do conformal RT then prefer an APBI dose of 30 in 5 with VMAT technique.
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Answer from: Radiation Oncologist at Academic Institution
My standard "whole breast" fields are now similar to the approach used in the IMPORT-LOW trial, though more generous - that is, the field borders are placed 4-5 cm beyond the excision cavity, compared to the 2.5-3 cm used in the trial. We commonly add a lightly-weighted anterior oblique to improve h...
Answer from: Radiation Oncologist at Academic Institution
I would say, I almost never add a 3rd field. I have seen excellent outcomes and toxicities with mini tangents alone with very low lung and heart doses.
Answer from: Radiation Oncologist at Community Practice
The "IMPORT" in IMPORT-LOW stands for Intensity Modulated Partial Organ RT. It's interesting that in some of the responses above, question answerers are using seemingly non-IMRT techniques... or at the least, not pointing out that the Intensity Modulated Partial Organ RT trial was perhaps allow...