251 Effect of breathing on contralateral breast doses in patients with breast carcinoma receiving radiotherapy

Abstract

Several accelerated partial breast irradiation (APBI) techniques are described in the literature, and apparently, the three-dimensional (3D)-conformal technique is being used increasingly. Nonetheless, the optimal radiation dose is not yet known. Here, we report feasibility and early toxicities of APBI delivering 40 Gy over 5 days, in a phase II trial.From October 2007 to September 2008, 25 patients with pT1N0 cancer received 3D-conformal APBI. The prescribed radiation dose was 40 Gy in 4-Gy fractions given twice daily. This technique used two minitangents and an “en face” electron field. Toxicities were systematically assessed at 1, 2, and 6 months and then once every 6 months.The planning tumor volume for evaluation (PTV_EVAL) coverage was adequate: the mean dose to the PTV_EVAL was 41.8 Gy (range, 41–42.4 Gy). Mean doses to the ipsilateral lung and heart were 1.6 Gy (range, 1.0–2.3 Gy) and 1.2 Gy (range, 1.0–1.6 Gy), respectively. One and two months after completion of APBI, most patients had no or mild erythema (n = 16 patients at 1 month; n = 25 patients at 2 months); none of these patients developed moist desquamation. After a median follow-up of 12 months, only 1 patient had a significant moderate field contracture (grade 2). Other reported late toxicities were grade 1.3D-conformal APBI (with two minitangents and an “en face” electron field) using a total dose of 40 Gy in 10 fractions twice daily over 5 days achieved appropriate PTV_EVAL coverage and offered significant sparing of normal tissue. Early tolerance was excellent.