Abstract book - ESTRO meets Asia

S77 ESTRO meets Asia 2018

later, a local recurrence of cancer [ER+, PgR-, HER2(3+), Ki-67 34%] was found in the range of 10cm. Letrozole, Anastrozole and Trastuzumab were administered but the recurrent lesion progressed. Then we decided salvage KORTUC (45Gy) for it after careful informed consent. Case2: 83-year-old woman felt a lump in the right breast and received an incisional biopsy [adenoid cystic carcinoma, ER<5%, PgR-, HER2(1+ ） ] in 2007. She denied an additional operation and only received irradiation (50Gy+ boost 10Gy). 7 years later, a local recurrence of cancer was recognized and removed surgically (right Bt+SN, Sn unknown and addition of Ax, n-). She denied adjuvant chemotherapy. Only 4 months after the surgical operation, she relapsed (nodular lesion 40mm x 20mm in size along the incisional scar) again. We selected salvage KORTUC (45Gy) for the lesion after careful informed consent. Results Acute dermatitis were Grade3 in case1 and Grade2 in case2 (Common Terminology Criteria for Adverse Events version 4), respectively. Severe adverse events have not been observed for 3 years in case 1 and for 2 years in case2, respectively. The local recurrent lesions were disappeared in the both cases. Conclusion KORTUC is suggested one of safe and effective salvage arms for recurrence of breast cancer. We should observe them carefully in long term and accumulate other similar cases to prove KORTUC alternative option for these conditions. PO-191 Cardiac and lung doses for breast cancer patients with free breathing and breath hold technique M.R.U. Nabi 1 , S. Poudel 2 , K.R. Mani 1 1 United Hospital Limited, Department for Radiotherapy and Radio-Oncology, Dhaka, Bangladesh 2 Nepal Cancer Hospital & Research Center- Nepal, Department of Radiotherapy-, Harisiddhi- Lalitpur-, Nepal Purpose or Objective To investigate the cardio-pulmonary doses between Deep Inspiration Breath Hold (DIBH) and Free Breathing (FB) technique in left sided breast irradiation Material and Methods DIBH CT and FB CT were acquired for 10 left sided breast patients who underwent whole breast irradiation with or without nodal irradiation. Three fields single isocenter technique were used for patients with node positive patients along with two tangential conformal fields whereas only two tangential fields were used in node negative patients. All the critical structures like lungs, heart, esophagus, thyroid, etc were delineated in both DIBH & FB scan. Both DIBH and FB scan were fused with the dicom origin as they were acquired with the same dicom coordinates. The critical structures of the FB scan were transferred to the DIBH dataset with reference to the dicom origin. Plans were created in the DIBH scan for a dose range between 50Gy in 25 fractions. Critical structures doses were recorded from the Dose Volume Histogram for both the DIBH and FB data set for evaluation. Results The average mean heart dose reduced (13.18 Gy vs 6.97 Gy, p=0.0063) significantly with DIBH as compared to FB technique. The average relative reduction in average mean heart dose was 47.12%. The relative V5 reduced by 14.70% (i.e. 34.42% vs 19.72%, p=0.0080), V10 reduced by 13.83% (i.e. 27.79 % vs 13.96%, p=0.0073). V20 reduced by 13.19% (i.e. 24.54 % vs 11.35%, p=0.0069), V30 reduced by 12.38% (i.e. 22.27 % vs 9.89 %, p=0.0073) significantly with DIBH as compared to FB.

The average mean left lung dose reduced slightly by 1.43 Gy (13.73 Gy vs 12.30 Gy, p=0.4599) but insignificantly with DIBH as compared to FB. Relative V5 decreased by 1.26 percent (37.95 Vs 36.69, p=0.0798), V10 decreased by 2.71 percent (30.20 vs 27.49, p=0.0539), V20 decreased by 3.14 percent (26.05 vs 22.91, p=0.4451), V30 decreased by 2.9 percent (23.75 vs 20.85, p=0.4585) but insignificantly with DIBH as compared to FB. Conclusion DIBH shows a substantial reduction of cardiac doses but slight and insignificant reduction of pulmonary doses as compared with FB technique. Using the simple DIBH technique, we can effectively reduce the cardiac morbidity and at the same time radiation induced lung pneumonitis is unlikely to increase. PO-192 To compare two boost protocols of hypofractionated RT with VMAT in patients with breast cancer S. Gupta 1 , B.S.Yadav 1 , D. Dahiya 2 , A. Oinam 1 1 Post Graduate Institute of Medical Education and Resear ch, radiotherapy, Chandigarh, India 2 Post Graduate Institute of Medical Education and Resear ch, General surgery, Chandigarh, India Purpose or Objective Dosimetric comparison of hypofractionated simultaneous integrated boost (SIB) versus sequential boost (SB) approach with Volumetric Modulated Arc Therapy (VMAT) after breast-conserving surgery (BCS) in breast cancer (BC) patients. Material and Methods A total of 55 BC patients were enrolled in this phase II study approved by IEC and registered with CTRI (registration number CTRI/2018/04/013008). A total of 35 women were assigned to the SIB arm, 20 to the SB arm randomly. This study compared the target volume coverage and normal tissues sparing with SIB-IMRT and SB- IMRT. Planning 4DCT was done and images were transferred to a commercial planning system for structural delineation. The CTV included the whole breast volume and CTV nodal ( if nodal irradiation was indicated) in both arms. A margin of 0.7cm was given to form PTV in both arms. CTV BOOST was contoured based on the seroma of cavity or clips placed during the lumpectomy. ITV was generated for both arms and a PTV margin of 0.5cm in SIB and 1cm in SB arm was given. A commercial IMRT treatment planning system (Varian) was used to provide treatment planning. For SIB, the dose prescribed to PTV was 34 Gy (3.4Gyx10 Fr) and 40 Gy was given to PTV boost (4 Gyx10 Fr). For SB , dose delivered to PTV was 34 Gy (3.4Gyx10 Fr) and PTV boost of 8Gy (4 Gyx2 Fr) was given. A statistical analysis with Paired Student's t-test was used to compare the dose-volume-histogram of target volumes and critical organs between the two techniques. Results The mean PTV volume was 1215.6 ± 566.9 ml and 1160.6 ± 522.8 ml and PTV boost volume was 74.5 ± 46.9 ml and 69.6 ± 56.2 ml (p=0.7) in SIB and SB arms, respectively. The mean dose to PTV was 35.40 ± 1.41 Gy and 34.75 ± 0.54 Gy (p=0.05) for SIB and SB, respectively. The mean PTV boost dose was 40.86 ± 1.29 Gy for SIB and 40.39 ± 0.80 Gy (p=0.1) for SB. Homogeneity index (HI) was better for SIB than SB techniques (p = 0.03) with comparable target coverage. D98 was also better in SIB arm (p=0.015) than SB. The mean dose to the contralateral (C/L) lung was 7.82 ± 3.6 Gy and 10.38 ± 5.4 Gy in SIB and SB (p=0.042), respectively. Mean heart dose was similar in both arms, 18 ± 1.9 Gy. Mean dose to the LAD depended significantly upon the laterality of the breast treated (p=0.001). The mean dose to the LAD was 3.5 ± 1.3 Gy for right sided and 6.2 ± 1.6 Gy for left sided for SIB and 3.4 ± 1.1 Gy for right sided and 6.8 ± 1.9 Gy for left sided for SB, respectively. The mean dose to the ipsilateral lung, C/L breast, and spinal cord were lower with SIB but