Whole breast proton irradiation for maximal reduction of heart dose in breast cancer patients

Abstract

Purpose In left-sided breast cancer radiotherapy, tangential intensity modulated radiotherapy combined with breath-hold enables a dose reduction to the heart and left anterior descending (LAD) coronary artery. Aim of this study was to investigate the added value of intensity modulated proton therapy (IMPT) with regard to decreasing the radiation dose to these structures. Methods In this comparative planning study, four treatment plans were generated in 20 patients: an IMPT plan and a tangential IMRT plan, both with breath-hold and free-breathing. At least 97 % of the target volume had to be covered by at least 95 % of the prescribed dose in all cases. Specifically with respect to the heart, the LAD, and the target volumes, we analyzed the maximum doses, the mean doses, and the volumes receiving 5–30 Gy. Results As compared to IMRT, IMPT resulted in significant dose reductions to the heart and LAD-region even without breath-hold. In the majority of the IMPT cases, a reduction to almost zero to the heart and LAD-region was obtained. IMPT treatment plans yielded the lowest dose to the lungs. Conclusions With IMPT the dose to the heart and LAD-region could be significantly decreased compared to tangential IMRT with breath-hold. The clinical relevance should be assessed individually based on the baseline risk of cardiac complications in combination with the dose to organs at risk. However, as IMPT for breast cancer is currently not widely available, IMPT should be reserved for patients remaining at high risk for major coronary events.

Radiation burden from modern radiation therapy techniques including proton therapy for breast cancer treatment - clinical implications

“…The results of this comparison showed that proton treatments could improve target coverage and reduce normal tissue burden and the integral dose in both gated and free breathing patients. These results are comparable with and add to those from recent similar studies that only investigated whole breast treatments (Mast et al 2014, Lin et al 2015.…”

“…Investigating the potential of the technique for proton therapy was the subject of one study in this thesis (Paper IV) as few studies have investigated this aspect of proton therapy (Mast et al 2014, Lin et al 2015. The more general impact of the breathing motion on dose distributions from proton radiotherapy has been addressed in another study in this thesis (Paper V).…”

Proton Therapy for Primary Breast Cancer

“…The dosimetric advantages of protons versus modern photon techniques were confirmed by several other publications (Cuaron et al [10], Mast et al [11], and Bradley et al [12]). The photon versus proton planning comparison study by MacDonald et al [13] revealed for comprehensive treatment with inclusion of internal mammary LN an ipsilateral lung volume receiving 20 Gy (V-20) of 30% with photons versus 15% with protons, and a mean heart dose of 4-10 Gy compared to <1 Gy, respectively.…”

Proton Therapy for Breast Cancer: Progress & Pitfalls

“…Numerous dosimetric studies clearly support the advantage of PBT at improving target coverage while simultaneously decreasing dose to the heart, coronary vessels, lungs and contralateral normal tissue compared with photon advanced planning techniques. These advantages are evident whether the target is partial breast, whole breast/chest wall or breast/chest wall and regional lymph nodes (Table 1) [20,[37][38][39][40][41][42][43]. A recent paper assessed the potential absolute gains with PBT compared with photon therapy in patients with left-sided breast cancer requiring comprehensive nodal irradiation.…”