P-255 Outcome of local radiation therapy in oligo-recurrent biliary tract cancers

Abstract

The role and impact of local treatment in the form of radiotherapy in oligo-recurrent biliary tract cancer is not very well defined. The aim of our study was to evaluate the efficacy of local radiotherapy in selected oligo-recurrent biliary tract cancer patients. In this retrospective analysis (2014-2021), we included patients with a performance status of 0-2, oligoreccurence post complete treatment, with a maximum of 5 lesions at 2 sites and all patients being on Gemcitabine based systemic therapy. Tumour response was graded according to RECIST 1.1 criteria. Endpoints were local control (LC), distant metastasis-free survival (DMFS) and overall survival (OS). A total of 23 patients of median age of 55 years of which 12 were females, were included. 9 patients had a nodal recurrence in the porta and or para-aortic region, 7 had isolated tumour bed recurrence, 5 had both and two were other sites. 68% of patients had primary of Gall bladder while remaining cholangiocarcinoma. All patients received 6-8 cycles of Gemcitabine based systemic therapy as per medical fitness and clinical suitability and were considered for Local radiotherapy if they remained stable after initial chemotherapy. Fourteen patients (61%) received radiation to a dose of 50-60Gy in 25 fractions while others received hypofractionated image guided radiotherapy (35-46Gy in 5-6 fractions). The median biologic effective dose (BED) was 67 Gy (IQR: 60 – 74). The 1 and 2 years OS was 84+11% and 67.2+17.4% respectively. At the median follow up of 13 months, the LC, DMFS were 76.6+10.4 and 61.1+13% respectively. Although there was no identifiable factor associated with better LC, DMFS or OS, in general, Gall bladder recurrences had higher curves than cholangiocarcinoma patients (p>0.05). There was no grade 3 or above radiotherapy related toxicities seen. Our study shows that Local therapy in the form of radiotherapy for oligo-recurrent biliary tract cancer is a feasible and effective approach to provide decent local disease control in the background of continued appropriate systemic therapy. Prospective trials are warranted to improve patient selection and to better define the integration of SBRT into a combined-modality treatment.