ESTRO 2021 Abstract Book

S1182

ESTRO 2021

Russian Federation

Purpose or Objective To study the clinical features and the effectiveness of radiotherapy in patients with bone metastases of gynecological cancer Materials and Methods Bone metastases of gynecological cancer are one of the rare distant sites that have been reported. Out of 810 cases of radiotherapy for bone metastases included in the long-term randomized trial gynecologic malignancies were diagnosed in 15 (1.9%) cases. There were 8 cases of cervical cancer (CC) and 7 cases of endometrial cancer (EC). Most of the remaining cases were breast cancer – 62.0%, prostate and lung cancer - 8.1% each, kidney cancer – 6.9%. Patient selection criteria for radiotherapy were non-stopping pain, the impossibility of surgical correction of pathological fracture/malignant spinal cord compression, increasing neurologic dysfunction. Irradiation volume included one anatomical area of the skeleton with the affected area. We used external 3-D conformal or volume-modulated photon radiotherapy. According to the research protocol the total dose was 13-26 Gy in 2-4 fractions of 6.5 Gy. Results The median follow-up was 70 months. Patients with bone metastases of the CC were significantly younger than patients with any other localization of the primary tumor - 46.2 years (p=0.051), and for almost 20 years younger than women with EC. The frequency of spinal irradiation in patients with gynecological cancer was 47,8%. Metastases in the pelvic bones were observed in 30.9%, in the long bones – in 12.5%. The lesion length and the initial pain intensity did not differ from other localizations of the primary tumor. The overall effectiveness of radiotherapy (complete + partial effect) in patients with CC and EC was 75% and 100%, complete response rate (CRR) was achieved in 50% and 57.1% of the cases respectively. There were no cases of bone pain recurrence in irradiation area during follow-up period. These results allow us to classify bone metastases of CC and EC as moderately radiosensitive. The CRR turned out to be lower than for bone metastases of breast, prostate cancers and melanoma with CRR>60%, and higher than for bone metastases of lung, colon and kidney cancers with CRR<40%. However, these results were not statistically significant. Conclusion The total dose 26 Gy in 4 fractions of 6.5 Gy is an effective radiotherapy option for non-solitary bone metastases of cervical and endometrial cancer. PO-1441 Single fraction Lumbopelvic Bone Irradiation with Tomotherapy for widespread bone metastases B. Gil Haro 1 , S. Santana Jiménez 1 , I. Zapata Paz 1 , R. Molerón Mancebo 2 , R. Rodríguez Romero 3 , P. Sánchez Rubio 3 , J. Velasco Jiménez 1 , R. Benlloch Rodríguez 1 , M. Hernández Miguel 1 , M. López Valcárcel 1 , S. Córdoba Largo 1 , O. Engel 1 , C. De La Fuente Alonso 1 , J. Romero Fernández 1 1 Puerta de Hierro University Hospital, Radiation Oncology, Madrid, Spain; 2 Aberdeen Royal Infirmary NHS Grampian, Radiation Oncology, Aberdeen, United Kingdom; 3 Puerta de Hierro University Hospital, Medical Physics, Madrid, Spain Purpose or Objective To assess the effectiveness and toxicity of single-fraction Lumbopelvic Bone Irradiation (LPBI) with Helical Tomotherapy (HT) in patients with widespread bone metastases. Materials and Methods Between May 2010 and November 2020, twenty-five patients with multiple painful bone metastases were treated with LPBI in our institution. Clinical characteristics: 16 males (76.5%), 9 females (23.5%); mean age: 65 yo (32-85). The most frequent primary tumors were prostate (9) and lung (8) adenocarcinoma. All but one patient had received systemic treatment. Radiation therapy: the PTV included all bones from the middle third of the femur to D9-L4 (depending on the extent of the disease) plus 5 mm symmetrical margin. A single dose of 8 Gy was administered to all patients except 2 patients who had received prior irradiation in whom 6.5 was administered. The dose to organs at risk (OARs) was calculated for bowel, bladder, rectum, liver and kidneys. Patients were premedicated with 8 mg dexamethasone, 8 mg ondansetron and 500cc saline solution, before and after radiotherapy. Analgesics consumption, ECOG, subjective pain relief and pain level (Visual Analog Scale –VAS–from 0 to 10) were evaluated. CTCAEv5.0 criteria were used to evaluate toxicity. Statistics: Student’s T test and Kaplan-Meier. Results Median follow-up was 7.28 months (0-49). Complete or partial pain relief was observed in 23 patients (92%). The mean VAS score, evaluated at 3 weeks postradiotherapy, significantly decreased from 6.28 points (4-9) to 2.48 points (0-7) (p < 0.001). Withdrawal of opioid treatment due to pain relief occurred in one third of patients after treatment. In most of the patients, the tolerance was mild. One patient suffered a tumor lysis syndrome 48 hours after radiotherapy that was resolved with pharmacotherapy. None of 25 patients presented GU toxicity. Grade 1-2 toxicities were asthenia (8 patients), nausea (5 patients), hematologic (9 patients) including leukopenia (2 patients), lymphopenia (7 patients), anemia (9 patients) and thrombopenia (1 patient). Only one grade 3 lymphopenia was observed. One- and two-years OS were 25% and 12%, respectively (Image 1). Mean PTV was 3703.6 cc (1986.8 – 7178 cc). Mean V 95 was 92.98% (80-100%). Mean D 95 was 7.35 Gy (6-8.2 Gy). Mean homogeneity index according to RTOG was 1.08 (1.05 – 1.15). Doses to OAR are shown in Image 2.