ESTRO 2024 - Abstract Book

S524

Clinical - Breast

ESTRO 2024

<2 x 10 -16 1.89 x 10 -6

Left-sided treatment

5.64

1.25 1.82

4.94

1.63 1.79

0.00257**

5.22 x 10 -6 ***

IMRT (ref-3D CRT)

Simple

-8.73

-8.22

4.69 x10 -5

Complex

14.16

3.46

9.87

3.31

0.00295**

4.44 x 10 -14

<2 x10 -16 ***

BMI (kg/m2)

1.17

0.15 0.08 2.16 1.74

1.44

0.15

Age (years)

-0.09

0.244 0.316

Premenopausal

2.17

1.09 x 10 -8

1.73 x 10 -8 ***

Boost

10.04

9.95

1.75

Table 1 : Regression analysis of D50 to IMN, level 1 and ALTJ in breast +/- boost, no prescribed nodal irradiation. β=coefficient, SE=Standard error.

Conclusion:

Incidental dose to the IMNs, L1 and ALTJ varied considerably across the cohort, both within and between treatment centres. Lower incidental dose to the IMN, and higher incidental dose to L1 and ALTJ was associated with left-sided treatment, which is likely due to use of cardiac sparing strategies. Incidental dose to L1 and ALTJ was also predicted by increasing BMI, this could be contributing to increased risk of breast-cancer related lymphoedema reported with higher BMI(3).

Keywords: Incidental dose, toxicity, lymphoedema

References

1. Gross JP, Lynch CM, Flores AM, Jordan SW, Helenowski IB, Gopalakrishnan M, Cutright D, Donnelly ED, Strauss JB. Determining the Organ at Risk for Lymphedema After Regional Nodal Irradiation in Breast Cancer. Int J Radiat Oncol Biol Phys. 2019 Nov 1;105(3):649-658. doi: 10.1016/j.ijrobp.2019.06.2509. 2. Suk Chang J, Ko H, Hee Im S, Sung Kim J, Kyung Byun H, Bae Kim Y, Jung W, Park G, Sun Lee H, Sung W, Olson R, Hong CS, Kim K. Incorporating axillary-lateral thoracic vessel juncture dosimetric variables improves model for predicting lymphedema in patients with breast cancer: A validation analysis. Clin Transl Radiat Oncol. 2023 Apr 20;41:100629. doi: 10.1016/j.ctro.2023.100629. 3. Bundred, N., Foden, P., Todd, C. et al. Increases in arm volume predict lymphoedema and quality of life deficits after axillary surgery: a prospective cohort study. Br J Cancer 123, 17 – 25 (2020). https://doi.org/10.1038/s41416-020 0844-4

877

Digital Poster

Importance of left anterior descending artery contouring in left-sided breast cancer

Maite Ispizua Ojanguren, Leire Romo Tapias, Angel Rodriguez Sanchez, Celia Fernandez Trueba, Idoya Reta Decoreau, Jose Antonio Arresti Sanchez, Karla Berenice Urquilla Ventura, Lucia Flores Barrenechea, Maria Madrid