ESTRO 36 Abstract Book

S636 ESTRO 36 _______________________________________________________________________________________________

Purpose or Objective To evaluate acute skin toxicity and cosmesis in DCIS patients enrolled in a phase II trial of hypofractionated breast irradiation using VMAT. Material and Methods Patients treated for DCIS with breast-conserving surgery were eligible for a phase II trial of hypofractionated breast irradiation. All DCIS patients underwent VMAT technique to irradiate the whole breast with a total dose of 40.5 Gy delivered in 15 fractions over 3 weeks, without tumor bed boost. Acute skin toxicities were recorded according to RTOG scoring criteria, and late skin toxicities according to CTCAE v4.0. Cosmetic outcomes were assessed as excellent/good or fair/poor according to the Harvard scale. Results From May 2013 to March 2016, 123 DCIS patients accrued. Median age was 56 year (range 30-82 years). The median follow up was 18 months (range 6-63). Most of the tumors were moderately differentiated (51 %) with a no comedo subtype with necrosis DCIS histology (73 %). Sentinel node biopsy was performed in 57 patients (46,3 %). Concomitant hormonal therapy was administered in 16 %. At the end of RT treatment skin toxicity profile was G1 in 56% of the patients, G2 in 14%, no patients presented G3 toxicity. At six months of follow up skin toxicity was G1 in 25% of patients, no G2-G3 cases; cosmetic outcome was good/excellent in 92% of patients. At one year skin toxicity was G1 in 24% of patients; no G2-G3 toxicity was recorded; cosmetic outcome was good/excellent in 94% of patients. After an early evaluation of clinical outcomes we have found 3 cases of local relapse. Conclusion These results evidence that hypofractionated radiotherapy using VMAT is a safe option for DCIS. A longer follow up is needed to assess clinical outcomes and late toxicity. EP-1171 Thermography and association to high-grade radiation dermatitis: a prospective trial on 64 patients. N. Leduc 1 , V. Atallah 2 , A. Petit 1 , S. Belhomme 1 , P. Sargos 1 , V. Vinh-Hung 3 1 Institut Bergonié, Radiation Oncology, Bordeaux, France 2 University Hospital of Bordeaux, Radiation Oncology, Bordeaux, France 3 University Hospital of Martinique, Radiation Oncology, Fort-de-France, France Purpose or Objective Thermography has been successfully used for non-invasive imaging of various diseases. Radiation-induced dermatitis characterizes by an inflammatory state and sensation of heat. We designed a prospective, observational, single- center study to acquire data about the bi-dimensional evolution of temperature in the treated breast during the course of radiotherapy, seek possible association with the occurrence of dermatitis and eventually inquire about the predictive value of temperature increase over the future occurrence of radiation dermatitis. Material and Methods All consecutive patients treated for localized breast cancer at the University Hospital of Martinique between May and September 2016 were eligible for inclusion. Included patients were examined weekly by trained investigators for the occurrence of radiation dermatitis. A high-resolution frontal image of torso was taken every week. Treated and contralateral areas were compared. Results 64 patients were included. All demonstrated an increase in local temperature over the course of treatment. The occurrence of high grade radiation-induced dermatitis was significantly associated to a higher increase of local average temperature (1.88 vs. 1.15 °C, p < 0.0001).

Preliminary results analyzing the predictive value of prior temperature elevation over subsequent occurrence of high-grade radiation dermatitis showed highest sensitivity and specificity of respectively 75% and 69% with a temperature threshold of 1.4°C. Figure 1 demonstrates typical thermal images of torso at 0 and 50 Gy. Temperature is plotted in °C.

Conclusion This study demonstrated the feasibility of capturing local temperature elevation over the course of adjuvant radiotherapy for breast cancer. Maximal and average local temperature increased for all patients, confirming the intensity of inflammatory phenomena linked to irradiation. Patients suffering from high-grade radiation- induced dermatitis radiated noticeably more heat. Furthermore, they started doing so before the occurrence of clinical signs of dermatitis. As such, thermography showed promising results as a predictive tool for the occurrence of acute skin toxicity. EP-1172 Post-mastectomy radiotherapy with patient- tailored bolus using 3D printing for left breast cancer K. Yang 1 , Y. Chung 1 , W. Park 1 , S.G. Ju 1 , S.J. Huh 1 , D.H. Choi 1 , H. Cha 1 , J.Y. Park 1 , C.H. Na 1 1 Samsung Medical Center, Radiation Oncology, seoul, Korea Republic of Purpose or Objective Radiation exposure to the heart during radiotherapy for left breast cancer patients has a chance to increase the risk of cardiovascular disease. Also, radiation pneumonitis and decreased lung function associated with thoracic radiotherapy have been reported. The purpose of this study is to reduce heart and ipsilateral lung doses using an optimized chest wall electron beam therapy with patient- tailored bolus (PTB) using 3D printing technology for left breast cancer patients after mastectomy. Material and Methods Five patients with left breast cancer underwent computed tomography (CT) simulation for irradiation of left chest wall and supraclavicular fossa after mastectomy. We designed a virtual bolus on the chest wall to compensate the surface irregularities on CT images and developed a plan for chest wall electron beam therapy. Also, a rival plan for conventional tangential technique was done on the same CT. For both plans, supraclavicular field was planned using photon beam. For planning, virtual bolus was overridden by a density of material which would be used to make PTB with 3D printer. Dosimetric comparisons for target and organs at risk such as heart and ipsilateral lung were performed between the 3D PTB applied electron beam plan and tangential plan. Wilcoxon signed-rank test was used for statistical analysis. Results For cardiac dose, PTB applied electron plan showed lower D mean , D max . V5 Gy and V30 Gy than tangential plan (p=0.080, 0.043, 0.686 and 0.068, respectively). For ipsilateral lung,