Abstract P5-14-05: Preoperative accelerated partial breast irradiation (PAPBI) trial: First results on acute toxicity, complications and cosmetic results

Background The ongoing Preoperative Accelerated Partial Breast Irradiation (PAPBI) trial (NCT01024582) was based on the rationale that three-dimensional conformal external-beam radiation (3D-CRT) leads to more dose homogeneity compared with brachy-or intraoperative radiotherapy (RT). By irradiating preoperatively this can lead to more accurate tumor delineation and smaller irradiated volumes. As the tumor remains in situ during irradiation, more precise delivery of the radiation dose is guaranteed with CT cone beam linear accelerators, avoiding the uncertainties of the original tumor position in the operation cavity as is the case in postoperative RT. Tumor excision 6 weeks after RT removes the high dose volume tissue and can lead to better cosmesis. Methods and materials Patients 60 years, T ≤ 3 cm, pN0(sn) (sentinel node procedure before RT), ductal carcinoma, unifocal on mammogram and MRI, undergo preoperative RT (CTV = GTV + 2 cm, 10 × 4 Gy IMRT/VMAT over two weeks); 6 weeks hereafter a wide local excision is performed. Skin toxicity and fibrosis is scored using EORTC/RTOG criteria. Patients are followed during RT and on a 3-monthly basis. Cosmesis is scored and photographs are taken for analysis (BCCT.core project score). Results From May 2010- 2013, 58 patients (pts) were included. For 52 pts follow up information is available up to at least 3 months after treatment; mean age 67.2 years (59-80); mean tumor size 1.4 cm (0.4-3.2); differentiation grade: grade 1 (n = 22), grade 2 (n = 28), unknown n = 8; mainly ER+PR + neu- (n = 50). 34 pts received hormonal therapy, none chemotherapy. Toxicity Acute RT toxicity grade 0 (23) grade 1(8). Postoperative complications were noted in 9/52 pts (17%): 2/52 had direct post-operative bleeding needing re-surgery; 1/52 developed a hematoma two months after surgery, needing re-surgery; 6/52 (11.5%) had a postoperative wound infection and received oral antibiotics. Of these 6; 1 wound abscess needing re-surgery; 1 small fistula closing within ten months. In the first year 9/52 pts developed localized oedema at the RT side fading away within 9 months. 4/53 pts developed hematoma post surgery. Fibrosis and cosmetic outcome Fibrosis score at 1 year (n = 35): grade 0 (9), grade 1 (21), grade 2 (4) grade 3 (1). Cosmetic outcome was scored at 1 year (n = 28): excellent/good (25; 89%), fair (3;11%). At 2 years follow up: 10/11 patients excellent/good and 1/11 patient fair. Fibrosis was noted in a limited volume. One ipsi-lateral breast tumor recurrence was diagnosed after 12 months at skin entry of the biopsy tract. Discussion The short term results of this PAPBI trial are promising in terms of acute treatment-related toxicities, complications and cosmetic outcome. Our complication rate of 17% (11% wound infection, 8% hematoma) is comparable with others*. Excellent or good cosmetic outcome was found in 90%, improving over time. Longer follow-up and increasing patient inclusion are needed to evaluate treatment efficacy, cosmetic results and toxicity on the longer term. *Mukesh et al (Eur J Surg Oncol 2012; 648 pts Cambridge IMRT trial), 18% infection, 8% hematoma. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-14-05.