ESTRO 36 Abstract Book

S385 ESTRO 36 _______________________________________________________________________________________________

4 European Institute of Oncology, Department of Urologic Surgery, Milan, Italy 5 European Institute of Oncology - University of Milan, Department of Urologic Surgery, Milan, Italy 6 European Institute of Oncology - University of Milan, Department of Medical Imaging and Radiation Sciences- Department of Oncology and Hemato-oncology, Milan, Italy Purpose or Objective To report toxicity and efficacy of moderately hypofractionated external-beam radiotherapy in a large series of patients treated for prostate cancer in a 9-year period. Material and Methods Between January 2007 and December 2015, 590 T1- T3N0M0 prostate cancer patients received 70.2 Gy in 26 fractions at 2.7 Gy/fraction (equivalent to 84 Gy in 42 2- Gy fractions, considering α/β of 1.5 Gy) using image- guided three-dimensional conformal radiotherapy (3D- CRT) and intensity modulated radiotherapy (IMRT). Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer criteria (RTOG/EORTC) and Houston definition (nadir + 2) were used for toxicity and biochemical failure evaluation, respectively. Results All patients completed radiotherapy. Mean age was 72.6 years (6.5 standard deviation). Fourteen patients were lost to follow-up. Information on gastrointestinal (GI) toxicity was available for 306 (54.4%) patients. Of these, 287 patients (93.7%) reported G0-G1 GI toxicity, with prevalence of G0 (84.6%), 13 (4.3%) G2 toxicity, 6 (2.0%) G3-G4 toxicity (table 2a). Information on genito-urinary (GU) toxicity was available for 306 (54.4%) patients. Of these, 277 patients (91.2%) reported G0-G1 GU toxicity, with prevalence of G0 (68.8%), 26 (8.6%) G2 toxicity, 1 (0.3%) G3-G4 toxicity (table 2b). At univariate analysis, age>80 years, increasing initial risk category, increasing Gleason score, increasing prostate-specific antigen (PSA) and the seminal vesicle involvement were associated with increased mortality. At multivariate analysis, Gleason score was the only predictor of mortality, even after adjustment for age. At univariate analysis, increasing risk, increasing Gleason score, increasing PSA and seminal vesicle involvement were associated with disease progression. At multivariate analysis, Gleason score was the stronger predictor of disease progression, even after adjustment for age.

prostate cancer in terms of toxicity and clinical outcome.

PO-0733 Radium 223: Difference in clinical outcomes between young and old Y.P. Song 1 , T. Ellis 2 , R. Walshaw 1 , J. Logue 1 , O. Parikh 2 , A. Choudhury 1 1 The Christie NHS Foundation Trust, Clinical Oncology, Manchester, United Kingdom 2 Lancashire Teaching Hospitals NHS Foundation Trust, Clinical Oncology, Preston, United Kingdom Purpose or Objective The commonest metastatic site for prostate cancer is the bone. The alpha-emitting radioisotope, Radium 223 (Ra223) has been shown to be effective in symptom management and improving overall survival in patients with metastatic castrate resistant prostate cancer (mCRPC). The balance between clinical benefit and impact of treatment in older patients is important to consider as over 50% of newly diagnosed patients in the UK are over the age of 70. We hypothesized that there would be no difference in outcome between the two groups. The aim of this clinical study is to examine the toxicities and clinical benefits of Ra223 between older and younger patients. Material and Methods Data from all patients treated with Ra223 in two tertiary cancer centres from December 2013 to February 2016 was collected retrospectively. Patients were divided into two groups – those 72 years and above at the time of commencing treatment, and those below 72, as the median age of patients treated in the landmark ALSYMPCA trial was 71. Toxicities were graded with CTCAE version 4. Statistical analysis was carried out using SPSS version 24. Results A total of 129 patients were treated during this period. The median age was 71 (range: 55-89). 65 (50.4%) were below 72 years while 64 (49.6%) were 72 and above. Patients received a median of 5 cycles (range: 1-6) of Ra223 at a dose of 50kBq/kg. 41 (63%) younger patients and 38 (59%) from the older group had had previous abiraterone while 20 (31%) and 15 (23%) respectively had had previous enzalutamide. 41 (63%) from the younger group were previously treated with docetaxel compared to 24 (38%) older patients (p=0.004). 11 (16.9%) of the younger patients and 4 (6.3%) of the older patients had had previous carbazitaxel. 51% of those below 72 and 59% of those 72 and above reported an improvement in symptoms (p=0.326). The median overall survival from starting Ra223 was 8.2 months (0.7-22.4) in the younger group and 8.6 (0.9-23.7) in the older group. Ra223 was well tolerated with 13 of 129 (10%) patients developing grade 3 (G3) anaemia. This included 11 (17%) from the younger group compared to 2 (3%) from the older group (p=0.009). There was one patient in each group with G3 neutropenia, but no neutropenic sepsis or G3 thrombocytopaenia. During the course of treatment, 11 (9%) patients developed a skeletal-related event. This included 3(5%) older patients and 8 (12%) younger patients Ra223 was well tolerated with minimal toxicities. However, a higher percentage of the young patients reported toxicities, with a statistically significant higher incidence of G3 anaemia. This may be associated with previous lines of treatment, since a larger proportion of patients below the age of 72 had had docetaxel in the past. There was no statistical difference between the younger and older patients with respect to symptomatic relief and median overall survival. Older patients had similar clinical benefit with Ra223 and should be considered in appropriate patients. (p=0.123). Conclusion

Conclusion The present study confirms that hypofractionated radiotherapy is a viable treatment option for localized