Breast radiotherapy in women with pectus excavatum (funnel chest): is the lateral decubitus technique an answer? A dosimetric study.

Breast radiotherapy is a technical challenge in women with pectus excavatum. We aim to assess isocentric lateral decubitus (ILD) technique as a means to irradiate breasts for patients with pectus excavatum. Four women presenting with left-sided breast cancers and found to have pectus excavatum were offered breast-conserving treatments. Post-operative breast radiotherapy was indicated (50 Gy) in two patients, with an additional boost to the tumour bed (16 Gy). Both ILD and supine techniques were simulated. We report the dosimetric comparison of these techniques and the acute skin toxicity of ILD radiotherapy. ILD permitted the same breast dose-homogeneity as the supine technique while decreasing breast thickness by 4.5-6.8 cm. The width of lung and/or heart receiving > 20 Gy ranged between 2.1 cm and 4.3 cm with the supine technique and between 0.5 cm and 1.1 cm with ILD. The estimated percentage of ipsilateral lung receiving > 20 Gy ranged from 21% to 34% with the supine technique and from 0% to 5% with ILD. Acute skin toxicity was scored 1 for all patients at completion of ILD radiotherapy. ILD is an effective breast radiotherapy technique for patients with pectus excavatum that preserves the underlying heart and lung from unnecessary toxicity.