ESTRO 36 Abstract Book

S628 ESTRO 36 2017 _______________________________________________________________________________________________

possible to distinguish between radiation toxicity and respiratory disease evolution. Late cardiac events were reported in 21 patients (2.7%), of which 17 had received anthracyclines and 9 trastuzumab. Three patients developed ischemic heart disease, within 5 to 7 years after radiotherapy; all of them had received anthracyclines and were irradiated at the left chest wall and LN, but also had many cardiovascular risk factors (2 to 4). Mean heart doses were 4.35Gy (2.1-6.6) and 1.7Gy (0.5- 2.9) and mean ipsilateral lung doses were 13.9Gy (10.8- 17) and 12.4 (8.6-16.1), in case of left and right chest wall and LN irradiation respectively. Conclusion This series shows that our PMERT technique is well tolerated at short and long term. EP-1166 Patterns of post-operative radiotherapy in breast cancer patients after neoadjuvant chemotherapy K.M. Lopes 1 , T.B. De Freitas 1 , H.A. Carvalho 1 , A.A. Pereira 2 , S.B. Silva 2 , S.R. Stuart 1 , M.S. Mano 2 , J.R. Filassi 3 , G.N. Marta 4,5 1 Faculdade de Medicina da Universidade de São Paulo, Radiation Oncology, Sao Pailo, Brazil 2 Faculdade de Medicina da Universidade de São Paulo, Clinical Oncology, Sao Pailo, Brazil 3 Faculdade de Medicina da Universidade de São Paulo, Breast Division, Sao Pailo, Brazil 4 Hospital Sírio-Libanês, Radiation Oncology, São Paulo, Brazil 5 Instituto do Câncer do Estado de São Paulo ICESP - Faculdade de Medicina da Universidade de São Paulo, Radiation Oncology, Sao Paulo, Brazil Purpose or Objective Neoadjuvant chemotherapy (NCT) has the same results as adjuvant chemotherapy in regard to disease-free survival and overall survival and may also allow breast conserving surgery for patients with locally advanced breast cancer. Indications for adjuvant radiotherapy (RT), as well as treatment targets after NCT are not yet well established. The purpose of this study is to evaluate locoregional RT indications and treatment targets in breast cancer patients submitted to NCT. Material and Methods Retrospective study of 523 patients treated between March 2010 and April 2015 that were submitted to NCT and received post-operative RT. Demographics, tumor and treatment characteristics were evaluated. The variables were submitted to descriptive and frequencies analysis. Comparisons of categorical variables among groups were made with the Chi-square test. Significance level was set at 5% (p < 0.05). Results The mean age was 50 years (range 22 to 84 years). Most patients had stage cT3 or cT4 disease (74.6%) and clinically positive lymph node(s) (81.5%). Luminal “like” tumors comprised 45% of the patients and 27.9% were triple negative. Biopsy for suspected axillary lymph node was performed in 49.5% (32.8% of these were positive). Conservative surgery was performed in 23.1%. All patients received breast or chest wall irradiation; 91.5% supraclavicular fossa (SCF) and axillary levels 2 and 3 irradiation, 1.4% only SCF; 8.7% underwent additional axillary level 1 irradiation and 8.8% also received internal mammary chain RT; boost was delivered in 21.4% of the patients. Conventional fractionation (25 x 200 cGy) was used in 96.6%. Indication of SCF and levels 2 and 3 axillary lymph nodes irradiation was significantly related to younger age (≤ 60 years)(p = 0.03), stage cT3 or cT4 (p = 0.027) and clinically compromised lymph nodes at the time of diagnosis (p = 0.0001). Internal mammary chain irradiation was also correlated to clinically positive lymph nodes (p = 0.01) and stage ypT3 or ypT4 (p = 0.028). Conclusion

AAPM TG 72 (needle method)

0.0 ÷ 20.0 mm (5.4 mm on the average)

11

5

2 mm

1 mm

Conclusion A new system for measuring the mammary gland thickness prior to IOERT developed at Vicenza Hospital was compared to a traditional needle method. The former shows better reproducibility and accuracy, because it reproduces the same target thickness as it exists after the docking. Regarding both treatment decisions and dosimetric accuracy, the found differences are critical when the international recommendations are followed. EP-1165 Short and long term safety of a post- mastectomy conformal electron beam radiotherapy (PMERT) N. Grellier-Adedjouma 1 , M. Chevrier 2 , H. Xu 1 , N. Fournier-Bidoz 1 , F. Campana 1 , F. Berger 2 , A. Fourquet 1 , D. Peurien 1 , D. Lefeuvre 2 , Y.M. Kirova 1 1 Institut Curie, Radiation Oncology, Paris, France 2 Institut Curie, Statistics, Paris, France Purpose or Objective To evaluate short and long-term safety of a chest wall irradiation after mastectomy with our previously published PMERT technique, depending on patient characteristics and treatments received. Material and Methods We included all women irradiated after mastectomy for a non-metastatic breast cancer with PMERT between 2007 and 2011 in our Department of Radiation Oncology. Acute and late toxicities (CTCAE v3.0) were evaluated with a weekly clinical examination during irradiation and then with monitoring consultations at least every 6 months. We also conducted a dosimetric analysis of 100 consecutive patients irradiated on the chest wall and lymph nodes (LN) (50 right and 50 left), to assess the doses to organs at risk. Results Among the 796 women included, mean age was 53.2 years (22.1-90.8), 47.6% of them had at least one cardiovascular risk factor, regardless of age, 49% were post menopausal, 8.3% were obese (BMI ≥ 30) and 6.9% and 11.9% had cardiac and pulmonary comorbidities respectively. Internal mammary chain (IMC) was irradiated in 85.6% of cases, supra, infraclavicular LN and axilla in 88.3%, 77.9% and 14.9% of cases. Mean chest wall dose was 49.4Gy (39- 56) over 40 days (30-119). Energies of 6 and/or 9 MeV were used in 84.7% of cases. The maximum acute skin toxicity was grade 1 in 58.5% of patients, grade 2 in 35.9%, and grade 3 in 4.5% of them. There was no grade 4 toxicity. Concomitant chemotherapy was associated with an increased risk of grade 3 toxicity (p <0.001). With an median follow up of 64.1 months (5.6-101.5), 29.8% of patients had, temporarily or permanently, hyperpigmentation, fibrosis or telangiectasia (grade 1: 23.6%, grade 2: 5.2%, grade 3: 1%), which tended to be promoted by smoking (p = 0.06); 274 patients (34.4%) underwent breast reconstruction, on average 19.7 months after the end of irradiation (3.6-86.8), which was considered as satisfactory or very satisfactory in 90% of cases. Lymphedema occurred in 17.1% of patients (minor: 14.4%, severe: 2.7%), related to axillary radiotherapy (p<0.001) and obesity (p=0.017). Long-term pulmonary toxicity reached 4% and was related to the irradiated volume. Among the 95 patients with pulmonary comorbidities, 9% experienced increased respiratory symptoms after radiation therapy; it is not