P0015 Is geometrical planning for lymphatic drainage safe practice? A single-institute review

Abstract

Background The planning of locally advanced breast cancer has long been a controversial topic. The aim of this study was to optimise the final conclusion about this controversy. Methods More than 25 patients with breast cancer (early and locally advanced) were treated with two tangential fields (group A) or either three or four fields (group B). 3D-geometrical plans were done regardless of the three axillary lymphatic drainage levels. Retrospectively, we analysed the dose-volume histograms of all plans and assessed the percentage of each level that received ⩾80% of the prescribed dose. Findings All patients were treated with a hypofractionated regimen, using 42.4 Gy in 16 fractions with or without boost. For level 1 axillary lymph nodes, the average dose for group A was 37.29 Gy versus 42 Gy for group B (p = 0.02). For level 2 axillary lymph nodes, the average dose was 26.89 Gy for group A versus 40.47 Gy for group B (p = 0.0009). For level 3 axillary lymph nodes, the average dose for group A was 22.32 Gy versus 37.08 Gy for group B. The percentage of each level of axillary lymph nodes that received ⩾ 80% of the prescribed dose at level 1 was 86.67% for group A versus 98% for group B (p = 0.0115); at level 2, 54.58% for group A versus 92.89% for group B (p = 0.00799); at level 3, 42.95% for group A versus 92.33% for group B (p = 0.00029). Interpretation 3D-geometrical planning for locally advance breast cancer using multiple fields to cover the axillary lymphatic drainage is an acceptable method, even with a hypofractionated regimen.