ESTRO 36 Abstract Book

S357 ESTRO 36 _______________________________________________________________________________________________

PO-0682 Re-irradiation for oligo-recurrence from esophageal cancer with radiotherapy history K. Jingu 1 , Y. Niibe 2 , H. Yamashita 3 , K. Katsui 4 , T. Matsumoto 5 , T. Nishina 5 , A. Terahara 2 1 Tohoku University Graduate School of Medicine, Department of Radiation Oncology, Sendai, Japan 2 Toho University Omori Medical Center, Department of Radiology, Tokyo, Japan 3 the University of Tokyo, Department of Radiology, Tokyo, Japan 4 Okayama University Graduate School of Medicine- Dentistry and Pharmaceutical Sciences, Department of Proton Beam Therapy, Okayama, Japan 5 Shikoku Cancer Center, Department of Gastrointestinal Medicine, Ehime, Japan Purpose or Objective to reveal the effectiveness and toxicity of re-irradiation for oligo-recurrence in lymph nodes from esophageal cancer treated by definitive radiotherapy or by surgery with additional radiotherapy Material and Methods We reviewed retrospectively 248 patients treated with (chemo)radiotherapy for oligo-recurrence in lymph nodes from esophageal cancer in 5 Japanese high-volume centers between 2000 and 2015. Of those 248 patients, 33 patients in whom re-irradiation was performed were enrolled in this study, and the results for patients in whom re- irradiation was performed were compared with the results for other patients. Survival estimates were calculated using the Kaplan-Meier method from the first date of radiotherapy for oligo-recurrence. Toxicity was graded according to the Common Terminology Criteria for Adverse Events (CTCAE v4.0). Results Median maximum lymph node diameter (MLD) was 22 mm (range, 5-106 mm). Median total radiation dose was 60 Gy (range, 18-70 Gy). Eleven of the 33 patients with a past irradiation history underwent re-irradiation by a hyperfractionation method. Therefore, the median calculated biological effective dose using the LQ model with α/β = 10 Gy (BED10) in patients in whom re- irradiation was performed was significantly lower than the median BED10 in others (Mann-Whitney U test, p<0.001). There were no other significant differences than BED10 in patients’ characteristics between the group with past irradiation history and the group without past irradiation history. Twenty-nine in the 33 patients performed concurrent chemotherapy with re-irradiation. The median observation period in patients in whom re-irradiation was performed was 14.9 months. The 3-year and 5-year overall survival rates in the 33 patients with a past irradiation history were 17.8% and 0%, respectively, with a median survival period of 16.0 months (95% C.I.= 7.0-17.6). The 3- year and 5-year overall survival rates in 215 patients without past irradiation history were 36.1% and 27.0%, respectively, with a median survival period of 21.5 months (95% C.I.= 16.4-26.6). There was a significant difference between the survival rates in the two groups (log-rank test, p=0.016). The 3-year irradiated field control rates in the 33 patients with a past irradiation history and in 215 patients without past irradiation history were 21.0% and 58.9%, respectively. There was a significant difference between irradiated field control rates in the two groups (log-rank test, p=0.001). Grade 5 toxicity occurred in 4 of 248 patients. Treatment related death, which was gastric hemorrhage, occurred in a patient in whom re-irradiation was performed. Conclusion Results of radiotherapy with or without chemotherapy for oligo-recurrence in lymph nodes from esophageal cancer in patients with a past irradiation history were insufficient compared with results for patients without a past irradiation history.

PO-0683 Impact of the radiation dose on hepatic perfusion evaluated using mebrofenin liver scintigraphy B. De Bari 1 , T. Breuneval 2 , M. Zeverino 3 , S. Godin 2 , L. Deantonio 4 , J. Prior 5 , J. Bourhis 2 , R. Moeckli 3 , M. Ozsahin 2 1 Hôpital Univ. Jean Minjoz, Radiation Oncology, Besançon, France 2 Centre Hospitalier Universitaire Vaudois, Radiation Oncology, Lausanne, Switzerland 3 Centre Hospitalier Universitaire Vaudois, Medical Physics, Lausanne, Switzerland 4 University Hospital "Maggiore della Carità", Radiation Oncology, Novara, Italy 5 Centre Hospitalier Universitaire Vaudois, Nuclear Medicine, Lausanne, Switzerland Purpose or Objective We aimed at evaluating the impact of the dose of radiotherapy (RT) on hepatic function (HF). HF variations were evaluated by integrating mebrofenin liver scintigraphy (HBS) before and after RT in patients treated with stereotactic body RT (SBRT) on liver. Material and Methods Between 04/2015 and 09/2015, 6 patients with primary (3 patients) or secondary liver cancers (3 patients) were treated with SBRT (3x15 Gy: 4 pts, 5x8 Gy: 1 pt or 6x5 Gy 1 pt). All patients received an HBS to assess HF before and three months after RT. HBS was co-registered with the planning phase of the simulation CT-scanner. The biological equivalent dose of 2 Gy per fraction (EQD2) was calculated for each patient with an alpha / beta = 10 Gy (acute toxicity). Isodoses (5, 10, 20, 30, 40, 50, 60, 70, 80, and 90 Gy) were drawn. Then, we calculated the activity (MBq) in these volumes before and after treatment. Results Linear regression analysis showed a significant reduction in HF at three months, which was proportional to the increase of the radiation dose (p = 0.0009, Figure 1). Our analysis showed a reduction of 0.78% of the HF for each delivered gray. Even with the limits of the small population of this study, the linear equation showed a predictive value in predicting the loss of HF/Gy of 96% (R 2 = 0.9605). Conclusion To the best of our knowledge, this is the first evidence available in the literature showing the utility of HBS in evaluating the variation of HF after SBRT. This analysis shows a functional decrease, which is proportional to the delivered dose, thus predicting the resulting acute toxicity. These functional based approaches could improve our knowledge about the response of the OARs to the radiation, and should be prospectively evaluated. PO-0684 Opposite pharmacokinetics of sorafenib modulates by liver irradiation – concurrent versus sequential C.H. Hsieh 1 , L.Y. Wang 2 , T.H. Tsai 3 , Y.J. Chen 4 1 Far Eastern Memorial Hospital, Radiation Oncology, Taipei, Taiwan 2 National Taiwan University, School and Graduate Institute of Physical Therapy, Taipei, Taiwan 3 National Yang-Ming University, Institute of Traditional Medicine, Taipei, Taiwan 4 Mackay Memorial Hospital, Radiation Oncology, Taipei, Taiwan Purpose or Objective Sorafenib is a multi-kinase inhibitor that demonstrated a significant improved survival of patients with hepatocellular carcinoma (HCC). The efficacy of radiotherapy (RT) concurrent or sequential with sorafenib in unresectable HCC patients has better effects than single agent. However, the effects of local RT on sorafenib in the plasma system remain unclear. Here, we evaluate the