Top Line: EORTC 22922/10925 found that the addition of regional nodal irradiation for node positive or central/medial breast cancer reduces breast cancer specific mortality.
The Study: Three techniques were used in the trial to cover the internal mammary nodes (IMN): a standard technique, a modified technique, and a personalized technique. The standard technique consisted of tangent fields matched to a medial supraclav/IMN field. The superior border of this field was 3 cm above the clavicular head, the inferior border was at the 4th rib, and the medial border was 1 cm across midline. In the supraclav part of the field (above the bottom of the clavicular head), the lateral border was the middle of the clavicle. In the IMN part, the lateral border was 5 cm lateral to midline. This field was treated with a ~50/50 mix of photons and electrons prescribed such that 95% photon isodose line encompassed the CTV and 85% of the electron isodose line encompassed the CTV. The modified technique allowed minor modifications of things like energy, gantry angle, and field width. The personalized technique allowed any modifications or field arrangements to cover the target. Participating centers (n=46) mostly stuck with one technique throughout the trial with 61% using the standard technique, 16% the modified technique, and 23% the personalized technique. In a quick flashback, there were concerns at the time of the trial that a personalized approach might actually diminish the benefit of RNI by compromising target coverage. That wasn’t the case. The absolute improvements in OS, DFS, and BCSM over the control arm were greatest with the personalized technique (+6.8%, +4.9%, -5.8%), followed by the modified (+1.6%, +2.9%, -4.3%), and finally the standard technique (+1.4%, +1.1%, -3%). Overall toxicity was similar among arms, however the standard technique increased pulmonary fibrosis by 5.2% in right sided cases.
TBL: Hopefully this isn’t news to anyone, but personalized treatment planning to cover the target volume while sparing the heart and lungs improves disease outcomes without increasing toxicity. | Kaidar-Person, Radiother Oncol 2022