ESTRO 2021 Abstract Book

S347

ESTRO 2021

Conclusion Our results suggest that bladder Dmax > 7.46Gy and D 2cc > 5.67Gy might be associated with acute and late GU toxicity in EC patients treated with VBT alone. However, no relation was found between GI toxicity and rectal doses. A larger prospective study would be neccesary to confirm the predictive value of these parameters. PH-0448 Advanced Brachytherapy for Re-Irradiation in Gynaecological Malignancies: Outcomes and Toxicities G. Mulye 1 , L. Gurram 1 , R. Mittal 1 , S. Chopra 1 , D. A. 2 , J. Ghosh 3 , S. Gupta 3 , S. T.S. 4 , A. Maheshwari 4 , U. Mahantshetty 1 1 Tata Memorial Centre, HBNI, Department of Radiation Oncology, Mumbai, India; 2 Tata Memorial Centre, HBNI, Department of Medical Physics, Mumbai, India; 3 Tata Memorial Centre, HBNI, Department of Medical Oncology, Mumbai, India; 4 Tata Memorial Centre, HBNI, Department of Surgical Oncology, Mumbai, India Purpose or Objective To evaluate the outcomes and toxicities of re-irradiation with advanced brachytherapy (BT) techniques for patients with post - radiation recurrent gynaecological cancers. Materials and Methods Methods & Materials A retrospective analysis of patients with post-radiation recurrent gynaecological (cervical, endometrial and vaginal cancers) who were treated with re-irradiation using BT between 2001 and 2019 was done. Treatment protocols and initial clinical outcome of 30 patients have been published earlier with a 2-yr local control and overall survival being 44% and 52% respectively. Seventy-six patients’ dataset was available for the final analyses. Patients underwent biopsy, restaging evaluation, and if deemed unsuitable for radical surgery were treated with re-irradiation using advanced BT techniques. Twenty-three patients (30.3%) underwent chemotherapy before consideration of reirradiation with brachytherapy. Descriptive statistics, survival outcomes & factors affecting outcome, and late toxicities were analyzed. Results Median age at recurrence was 55 years (Range: 35 to 73 years). 43 patients had recurrent cancer with intact utero-cervical canal and 33 had recurrent cancer of the vaginal vault (post radiation). Squamous cell carcinoma was the most common histology. Median gap between the 1 st and 2 nd radiation treatments was 25 months (IQR: 12 - 44). Vaginal involvement was seen in 52 patients (78%). BT application was done using MUPIT in 39, Vienna applicator in 20, Syed Neblett in 9, central vaginal cylinder in 3, multi-catheter intravaginal applicator, tandem and ovoids in 2 and the Houdek applicator in 1 patient. All patients completed planned HDR BT with various fractionation schedules. The median cumulative EQD2 was 108 Gy (IQR 92Gy-123Gy) The median EQD2 at 2 nd radiation was 40 Gy (IQR: 33-42 Gy). With a median follow-up of 33 months; local recurrence-free survival, disease-free and overall survival at 2 years was 62.2%, 59% and 69.5% respectively. On univariate analyses, systemic chemotherapy, volume of disease, time interval between 2 radiation treatments and RT doses delivered did not show any significant effect on outcomes. Grade 3-4 late rectal and bladder toxicities were seen in ten (13%) and six (8%) patients respectively; and vaginal fibrosis in twenty-four (31%) patients. Two patients developed fistulae, rectovaginal and vesico-vaginal fistula (no disease)- in 1 patient vesico-vaginal fistula (due to disease progression) in another patient. One patient developed vaginal necrosis six months post- and another patient developed intestinal obstruction five months post re-

irradiation. Conclusion

Patients with post radiation local recurrent disease treated with reirradiation using advanced BT resulted in reasonably favourable clinical outcomes. Re-irradiation with BT was associated with higher grade 3-4 morbidity, predominantly vaginal. Further evaluation to understand dose response relationship for target and OAR with re-irradiation BT schedules is warranted.