ESTRO 38 Abstract book

S730 ESTRO 38

47 (52.2%), and 18 (20%) of pts, respectively. Necrosis was observed in 46 cases (51.1%). All pts were estrogen receptor (ER) positive; 83 pts (92.2%) were progesterone receptor (PR) positive. Eleven pts (12.2%) underwent re- excision, and surgical margins were ultimately negative (≥ 0.2 cm) in all. Median calculated Van Nuys Prognostic Index (VNPI) score was 6 (3-9). Median calculated Memorial Sloan Kettering (MSK) nomogram value for 10yr IBR risk was 8 (2 - 20). Median DCIS Score® was 11(0-79); 72 pts had low risk scores (80%). 26 pts (28.9%) received RT: 5/7 pts who had high risk scores, 6/11 with intermediate and 15/72 with low risk scores. 57 pts (63.3%) received hormonal therapy. High risk DCIS Score® correlated with higher nuclear grade (p<0.0001), necrosis (p=0.009), higher VNPI (P=0.002), and PR negativity (p=0.001). Pts with higher DCIS Scores® were more likely to have received RT (p=0.001). The MSK nomogram results did not correlate with the DCIS Score®results (Pearson correlation coefficient 0.464). Median MSK recurrence risks per Oncotype groupings were 8% in the low Oncotype DCIS risk group, 8% in the intermediate and 7% in pts within the high Oncotype risk group (p=0.256). At a median F/U of 2.13 years (0.04- 6.45 years), there is no evidence of recurrence in any patient. Conclusion Pathologic factors including nuclear grade, necrosis, and PR status are strong predictors of DCIS Scores.® The VNPI correlated with DCIS Score®, whereas the more comprehensive and widely accepted MSK nomogram did not. Our results suggest a possible underestimation of risk by the MSK nomogram in those with intermediate-high risk DCIS Scores.® Long-term F/U is needed to confirm the validity of the DCIS Score® in our pt population, and to determine whether this assay versus the MSK nomogram can more accurately IBR risk. EP-1333 Myocardial changes detected using Cardiac MRI in left breast patients treated with Radiation S. Tang 1 , E.S. Koh 1 , R. Rai 2 , J. Otton 3 , D. Tran 3 , G. Delaney 1 , L. Holloway 2 , B. Schmitt 4 , G. Liney 5 1 Ingham Institute for Applied Medical Research, CCore, Liverpool, Australia ; 2 Ingham Institute for Applied Medical Research, Medial Physics, Liverpool, Australia ; 3 Liverpool Hospital, Department of Cardiology, Liverpool, Australia ; 4 Siemens Healthcare Pty Ltd, Siemens Healthcare, Sydney, Australia ; 5 Ingham Institute for Applied Medical Research, MRI Physics, Liverpool, Australia Purpose or Objective Acute cardiac changes following tangential breast radiation(RT) have been demonstrated using cardiac scintigraphic studies and advanced echocardiographic techniques. This study evaluates the prospective use of cardiac MRI (CMR) in detecting myocardial changes using serial cardiac mapping techniques over a 12 month period. Material and Methods For 21 left-sided female breast cancer patients(median aged 59 years(38-76)) receiving tangential RT(prospectively recruited between October 2015 and October 2016), three cardiac MRI scans were obtained; a baseline scan 2-3 days before adjuvant RT, 6 – 8 weeks and 12 months respectively following RT. No patients received chemotherapy. A clinical modified look-locker inversion(MOLLI) sequence was used to acquire myocardial short axis T1 maps, pre and 15 minutes post administration of gadolinium-based contrast agent(Gadovist), as well as T2 maps at 3Tesla. Myocardial partition coefficient(λ) was calculated according to (ΔR1myocardium/ΔR1blood), and extra cellular volume(ECV) was derived from λ by adjusting (1-haematocrit). Two independent T1/T2/ECV map segmentations of the left ventricle were obtained using cvi42, and averaged for analysis(see Figure 1). Single breath-hold SSFP cine acquisitions of the cardiac short axis

In this prospective phase II study conducted at the department of clinical oncology, Cairo university, breast cancer patients indicated for post-operative WBI following BCS were recruited to receive an accelerated hypofractionated WBI schedule of 40 Gy/15 fractions over 3 weeks with a concurrent daily boost dose of 8.0 Gy/15 fractions. Dosimetric parameters were set using V38Gy & V36Gy for breast PTV coverage, V45.6Gy and V43Gy for tumor bed PTV coverage, while Dmax and Dmin were used to evaluate homogeneity. Sixty three patients were recruited accordingly, and were followed up for acute toxicity (using CTCAE v3.0 criteria), Late toxicity ( reported at least 6 months after end of radiation course and thereafter) and cosmetic outcome (using Harvard The study was conducted during the period from June 2014 to June 2017. A total of 63 patients were recruited and followed for a median duration of 24 months (follow-up period ranged from 18 to 32 months). The recruited patients had a median age of 51 years (22-65 years), 24 patients had T1 tumors, 37 had T2 and only 2 recruited patients had T3 disease, and all were node negative. The dosimetric parameters for the coverage of target volumes and dose constrain for OAR were in compatible compliance with our protocol. The mean duration of the whole course of radiation (in days) was 22+/-2.1 days. About 20.63% of the patients had GII acute skin toxicity, while none developed GIII or more acute skin toxicity. As regard late skin toxicity (71.43%) of the patients had G0 late skin toxicity, and (28.57%) of the patients had G1 late skin toxicity no patients had G3 nor G4 late skin toxicity. Till last follow-up date, none of the recruited patients was documented to have >G0 heart nor lung toxicity. Also, none had documented loco-regional nor distant relapse. Regarding cosmetic outcome, 80.95% of the patients were reported as having excellent cosmetic score, while 19% were reported as good (as per Harvard criteria). Conclusion The proposed accelerated hypofractionated course of WBI with a concurrent TB boost shows acceptable acute toxicity and early cosmetic outcome, however longer follow up is required to better evaluate late toxicity, cosmetic & clinical outcomes. EP-1332 An Urban Institution’s Experience with the Oncotype DCIS Score: Predictors and Outcomes T.Y. Andraos 1 , A. Orisamolu 1 , J. Fox 1 1 Montefiore Medical Center, Radiation Oncology, Bronx, USA Purpose or Objective The Oncotype DCIS Score® is a validated predictor of ipsilateral breast recurrence (IBR) in patients (pts) treated with lumpectomy for ductal carcinoma in-situ (DCIS). Criteria for its use are subjective and physician- dependent, and used to guide decision making for adjuvant radiation (RT). We evaluated possible predictors of the DCIS Score® and report on outcomes to date in our pt population. Material and Methods DCIS Scores® were available on 90 women who underwent lumpectomy between December 2011 and June 2018. DCIS Scores® were reported as low (score 0-38), intermediate (39–54), and high risk (>54). 10 pts’ scores were the modified results accounting for age < or >50 and size < or > 1cm. Follow-up (F/U) was calculated from date of initial surgery to date of last mammogram or clinical exam. ANOVA, Chi-Square, and Pearson correlation tests were used to assess statistical comparisons between groups, with p <0.05 considered as statistically significant. Results Median age was 67 years (30-85). Median size on surgical pathology was 0.6 cm (0 – 4 cm), as measured on a single slide. Grade 1, 2, and 3 DCIS were present in 25 (27.8%), score). Results