P-201 Using SBRT in treating oligorecurrences of carcinoma of stomach

Abstract

The role and impact of local treatment in the form of radiotherapy in oligo-recurrent stomach cancer is not very well defined. The aim of our study was to evaluate the efficacy of stereotactic body radiation therapy (SBRT) in selected oligo-recurrent stomach 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 best available systemic therapy. Tumor 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 53 years of which nine were females, were included. 9 patients had anastomotic site recurrence, 11 had nodal, 2 had both while one was at the other sites. All patients were on systemic therapy as per medical fitness and clinical suitability while being considered for SBRT. The median biologic effective dose (BED) was 72 Gy (IQR: 52.8 – 75). The 1 and 2 years OS was 94.7+5.1% and 52.7+15% respectively. At the median follow-up of 15 months, the LC, DMFS were 76.1+9.4 and 74.5+10.1% respectively. Although there was no significant difference between LCR or DMFS for lymph node or tumor bed reoccurrence site SBRT; lymph node recurrence SBRT was significantly associated with better survival than in patients with tumor bed recurrence (HR: 0.066[CI:0.006-0.753] p=0.029). Our study shows that SBRT on oligo-recurrent stomach cancer is a feasible and effective approach in terms of local disease control. Lymph node recurrences may have a higher survival benefit 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.