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Erschienen in:
01.12.2014 | Original Research
A phase II trial of balloon-catheter partial breast brachytherapy optimization in the treatment of stage 0, I, and IIA breast carcinoma
Erschienen in: Journal of Radiation Oncology | Ausgabe 4/2014
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Objectives
This study aims to (a) prospectively determine if multiple dwell (multidwell) position dose delivery can decrease skin dose and resultant toxicity over single-dwell balloon-catheter partial breast irradiation and (b) evaluate whether specific skin parameters could be safely used instead of skin–balloon distance alone for predicting toxicity and treatment eligibility.
Methods
A single-arm phase II study using a Simon two-stage design was performed on 28 women with stage 0–II breast cancer. All patients were treated with multidwell position balloon-catheter brachytherapy. The primary endpoint was ≥ grade 2 skin toxicity. Initial entry required a balloon–skin distance of ≥7 mm. Based on the toxicity in the first 16 patients, additional patients were treated irrespective of skin–balloon distance as long as the D
max to 1 mm skin thickness was <130 %.
Results
Compared with the phantom single-dwell plans, multidwell planning yielded superior PTV coverage as per median V90, V95, and V100 but had slightly worse V150, V200, and DHI. D
max to skin was decreased by multidwell planning at multiple skin thicknesses. The most common acute toxicity was grade 1 erythema (57 %), and only two patients (7 %) developed acute grade 2 toxicity (erythema). Late grade 1 fibrosis was seen in 32 %. No patients experienced grade 3, 4, or 5 toxicity.
Conclusions
Multidwell position planning for balloon-catheter brachytherapy results in lower skin doses with equal to superior PTV coverage and an overall low rate of initial skin toxicity. Our data suggest that limiting the D
max to <130 % to 1 mm thick skin is achievable and results in minimal toxicity.