ESTRO 38 Abstract book

S464 ESTRO 38

K. Yasui 1 , H. Katagiri 2 , T. Onoe 1 , H. Ogawa 1 , H. Harada 1 , H. Asakura 1 , S. Maki 1 , A. Nakura 1 , Y. Ito 1 , M. Hirata 1 , S. Murayama 1 , Y. Honda 2 , M. Miyagi 2 , J. Wasa 2 , H. Murata 2 , M. Takahashi 2 , T. Nishimura 1 1 Shizuoka Cancer Center, Radiation oncology, Nagaizumi - Cho- Shizuoka, Japan ; 2 Shizuoka Cancer Center, Orthopedic surgery, Nagaizumi - Cho- Shizuoka, Japan Purpose or Objective To validate a predictive model for survival in patients with bone metastases who are receiving radiation therapy. Material and Methods We previously constructed a predictive model for patients’ survival using six prognostic factors: the primary lesion, visceral or cerebral metastases, abnormal laboratory data, poor performance status, previous chemotherapy, and multiple skeletal metastases. Each prognostic factor was assigned scores. Each patient was scored from 0-10 and classified into one of three groups: group A (those with scores 0-3), group B (those with scores 4-6), and group C (those with scores 7-10). This model was constructed from the records of 808 patients with bone metastases from 2005 to 2007. To validate the model, we evaluate 497 patients with bone metastases receiving radiotherapy from 2010 to 2012. Survival was estimated by the Kaplan- Meier method. The log-rank test was used to compare the survival times. Results The median survival was 6.1 months; group A (n = 54) 47.4 months (95% CI, 32.5-68.4 months); group B (n = 207) 10 months (95% CI, 8.4-13.1 months); and group C (n = 236) 3.5 months (95% CI, 2.6-4.0 months). The survival probability at 6, 12, and 24 months was 91%, 83%, 72%, respectively for group A; 70%, 45%, 19%, respectively for group B; and 28%, 8%, 3%, respectively for group C ( p < 0.001).

PRESENT cohort, treated with conventional radiotherapy or SBRT. Material and Methods We included all patients with oligometastatic bone disease (≤5 metastatic lesions within ≤3 different organs) enrolled in the PRESENT cohort between June 2013 and September 2017. Since SBRT was only available as a treatment option at our department since December 2014, all patients before that date were treated with conventional radiotherapy (3D-CRT, IMRT or VMAT). Main outcomes were pain response (duration of pain response and best response defined as ‘complete’, ‘partial’ or ‘stable response’), QoL (EORTC QLQ-BM22 and QLQ-C15-PAL), overall survival (OS), progression free survival (PFS), and time to start of, or switch in systemic treatment (FFSS) after radiotherapy. To control for potential confounders, patients were stratified into bone metastases only yes/no, histology (e.g. ‘favorable histology’ (breast or prostate) or ‘other histology’), interval between diagnoses of the primary tumor and detection of oligometastatic disease ≤ 12> months with correction for age and WHO performance. Results Of the 131 patients, 66 patients were treated with conventional radiotherapy ((1x8 Gy (44%), 5x4 Gy (12%), 10x 3 Gy (36%)) and 65 patients were treated with SBRT (1x 18Gy (35%), 3x10 Gy (30%) and 5x7 Gy (20%)). The median duration of follow-up was 46 and 25 months for the conventional radiotherapy and SBRT group respectively. There was no difference in best reported pain response within the first 12 months after treatment (pain response 81% vs. 84 %, p=0.79) or duration of the response (23 weeks (95% CI 1-58) versus 25 weeks (95% CI 0-50), p=0.79 in the SBRT group). All quality of life domains were similar, with the exception of physical functioning which was better in the SBRT group. The SBRT group demonstrated superior median OS (median OS not reached vs. 18 months) and PFS rates (median PFS 12 months (95% CI 5.3-18.6) versus 5 months (95% CI 3.5-6.5, p= 0.002) , figure 1). After correction for age and WHO performance, treatment with SBRT significantly prolonged OS and PFS in patients with an interval between primary tumor and oligometastatic disease >12 months (table 1). Treatment with SBRT did not affect FFSS in any subgroup within our cohort.

Conclusion Our predictive model can be utilized to predict prognosis for patients with bone metastases receiving radiation therapy. External validation is needed in order to confirm our findings. PO-0881 Outcomes of oligometastatic bone disease treated with conventional or stereotactic radiotherapy S. Van de Ven 1 , J.M. Van der Velden 1 , W.S.C Eppinga 1 , D.H.J.G Van den Bongard 1 , H.M. Verkooijen 1 1 UMC Utrecht, Radiation Oncology Department, Utrecht, The Netherlands Purpose or Objective Stereotactic body radiotherapy (SBRT) has become a widely adopted treatment for patients with oligometastatic bone disease, despite limited evidence of superiority. We compared patient-reported pain, quality of life (QoL) and survival outcomes of patients with oligometastatic bone metastases within the prospective