ESTRO 2020 Abstract book

S710 ESTRO 2020

Oligo-recurrence is a special case of oligometastases in which patients have limited number of metastatic lesions with a controlled primary tumor and local therapy may improve their prognosis. In this report, we evaluated the role of intensity modulated radiation therapy (IMRT) on the clinical outcomes of patients with lymph node oligo- recurrence. Material and Methods We retrospectively reviewed the medical records of 21 patients who had been diagnosed with lymph node oligo- recurrence and received IMRT between October 2010 and August 2017. Inclusion criteria were as follows: 1) oligo- recurrence occurred exclusively in the lymph nodes, 2) patients were treated with curative intent and 3) primary lesions were controlled. Results The median age at the start of IMRT for lymph node oligo- recurrence was 67 years (range: 39 to 81 years). Sites of primary lesions were the following: lungs 5, breasts 4, uterine 4, esophagus 2 and others 6. Primary histopathology was adenocarcinoma in 8 patients, squamous cell carcinoma in 5 patients and others in 8 patients. The location of the recurrent lymph node was regional only in 14 patients (66.7%), distant only in 6 (28.6%), and both regional and distant in 1 patient (4.8%). The gross tumor volume (GTV) included all detectable involved lymph nodes. The number of lymph nodes involved was single in 13 patients and multiple (2–5) in 8 patients. The median GTV was 9.6 cc (range: 1.4–80.0 cc). Seventeen patients (81.0%) received IMRT including in the regional lymph node area. Median IMRT dose to GTV was 60 Gy (range: 50 to 70 Gy). Twelve patients (47.1%) received some systemic therapy after diagnosis for oligo- recurrence. All patients completed the course of IMRT. Median follow-up period after their IMRT was 33.7 months (range: 6.2–71.3 months). At the last follow-up, 9 out of the 21 patients (43%) achieved progression-free survival. Two patients had exclusively in-field progression, 3 had out-of-field progression, and 7 had both. The three-year overall survival (OS) rate, in-field progression free survival (IFPFS) rate and out-of-field progression free survival (OFPFS) rate were 75%, 52% and 44%, respectively. Statistical analysis showed the following: 1) lower total dose and larger GTV size were significantly associated with worse OS rates, respectively, 2) adenocarcinoma and lower total dose were significantly associated with worse IFPFS rates, respectively, 3) older age and SCC were associated with better OFPFS rate, respectively. No patients experience grade 3 or higher acute or late adverse events except one, who developed acute grade 3 IMRT could be effective and safe for patients with lymph node oligo-recurrence and a curative treatment option for selected cases. Tumor dose escalation sparing normal tissue using IMRT technology may provide better overall and in-field progression-free survival. PO-1259 Adoption of single-fraction radiotherapy for uncomplicated bone metastases in a tertiary centre C. Peters 1 , J. Vandewiele 1 , Y. Lievens 1 , M. Van Eijkeren 1 , V. Fonteyne 1 , T. Boterberg 1 , P. Deseyne 1 , L. Veldeman 1 , W. De Neve 1 , C. Monten 1 , S. Braems 1 , F. Duprez 1 , K. Vandecasteele 1 , P. Ost 1 1 University Hospital Ghent, Radiation Oncology, Ghent, Belgium Purpose or Objective Single-fraction radiotherapy (SFRT) offers equal pain relief for uncomplicated painful bone metastases as compared to multiple-fraction radiotherapy (MFRT). Despite this evidence, the adoption of SFRT has been poor with published rates of SFRT for uncomplicated bone metastases ranging from <10% to 70%. We aimed to evaluate the adoption of SFRT and its evolution over time leukopenia. Conclusion

PO-1257 Use of Stereotactic Radiotherapy in lymph nodes for oligometastic pelvic tumors A. Rese 1 , F. Pastore 1 , M. Conte 1 , G. Ciaglia 1 , F. Francomacaro 1 , V. Iorio 1 1 Emicenter, Radiotherapy, Casavatore, Italy Purpose or Objective Oligometastatic desease has been defined as a state with 5 or fewer clinically detectable metastases. Patients with oligometastatic or oligorecurrence in lymph nodes could be cured with local therapy such as stereotactic body radiotherapy (SBRT). SBRT represents an emerging strategy. The aim of this retrospective study was to evaluate the oncological outcome and pattern of recurrence in patients treated with stereotactic body radiation therapy (SBRT) to lymph node metastases. Material and Methods In this mono-institutional analysis, patients with a maximum of three lymph node metastases from prostate cancer, bladder cancer and endometrial cancer treated with SBRT were included. All patients had a positive 18F-Choline PET/CT in case of prostate cancer or a positive 18FDG PET/CT in the other cases. Primary endpoints of the analysis were acute and late toxicities. Secondary endpoints were local control (LC), progression-free survival (PFS) and overall survival (OS). Results 26 patients were eligible and treated with SBRT from January 2016 to January 2019 and retrospectively analysed. 13 patients had prostate cancer, 7 bladder cancer and 6 endometrial cancer. 9 patients (69%) with prostate cancer had undergone radical prostatectomy. A total of 30 lesions were treated: 23 patients had one metastasis, while 2 patients had two metastasis and 1 had three metastasis. Patients' median age was 70.8 years (range 51-84). Median follow up was 16 months. The dose delivered to the target ranged from 24 to 35 Gy in 3-5 fractions; 8 Gy daily in 3 fractions, 10 Gy daily in 3 fractions or 7 Gy in five fractions. Toxicity was rare: 23 patients (88%) presented G1 genitourinary acute toxicity, 20 patients (77%) presented G1 gastrointestinal acute toxicity, none had G3 acute toxicity. No patients developed grade ≥2 late toxicity. Local control was achieved in 95%. LC at 1 was 91%. Two- years progression-free survival was 60% and the overall survival was 75%. Conclusion SBRT is an effective and well-tolerated treatment option in the management of lymph node metastases. A greater number of cases could help us better stratify patients, that could benefit from a dose or fractionation. PO-1258 Intensity modulated radiation therapy for lymph node oligo-recurrence A. Sato 1,2 , M. Omura 2 , Y. Minagawa 2 , K. Takino 2 , K. Matsui 2 , H. Hongo 2 , R. Shirata 2 , H. Hashimoto 3 , T. Misumi 4 , Y. Sasaki 5 , T. Inoue 6 , M. Hata 7 1 Yokohama City University Hospital, Radiation Oncology, Yokohama, Japan ; 2 Shonan Kamakura General Hospital, Radiation Oncology, Kamakura, Japan ; 3 Shonan Fujisawa Tokushukai Hospital, Radiation Oncology, Fujisawa, Japan ; 4 Yokohama City University Medical Center, Biostatistics, Yokohama, Japan ; 5 Shonan Kamakura General Hospital, Center for Clinical and Translational Science, Kamakura, Japan ; 6 Shonan Kamakura General Hospital, Advanced Medical Center, Kamakura, Japan ; 7 Yokohama City University Graduate School of Medicine, Radiation Oncology, Yokohama, Japan

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