Second chance for cure: Stereotactic ablative radiotherapy in oligometastatic disease.

Abstract

154 Background: Local ablative therapy, such as radiation therapy or surgery plays a key role in treatment of patients with oligometastatic disease. Stereotactic ablative radiotherapy (SABR) comes to the fore as a safe and effective treatment option for patients with a limited number of metastases, even those located in hard-to-reach body sites. Many researchers have suggested that metastatic direct therapy (MDT) could improve long-term progression-free and overall survival (PFS and OS) in patients with 1-5 metastatic lesions. Methods: This was a retrospective, single-arm, observational, evaluation study between July 2015 to February 2022. In our institute 60 patients with controlled primary tumors and 1-5 metastases were treated with SABR.We did not exclude patients who subsequently had intracranial metastases from the analysis (n 3). Prescribed radiation doses ranged from 24 to 60 Gy administered in one to seven fractions. Primary endpoint was PFS and the secondary endpoints were OS and toxicity. Results: The most common primary malignancy types were prostate cancer (n 14), colon (n 10), lung (n 7), breast (n 6), melanoma (n 6) and gynecology malignancies (n 6). Median follow-up was 30 months, ranging from 9 to 79. The 1, 3 and 5-year OS rate was 98,3%, 84,4% and 73,8% respectively, the median time to first progression was 15 (range 2 - 32) months. 36 (60%) patients have no recurrence. Two of three patients with intracranial metastases were alive at the end of the study. There were no grade 3-5 adverse events related to specific treatment of SABR. In our analysis, neither the number of metastases nor the primary site were independent prognostic factors. Conclusions: In our retrospective analysis, SABR was associated with high levels of PFS and OS in patients with oligometastatic disease. The limitations of our study were lacking high-level evidence, randomized studies to compare SABR and palliative standard-of-care are mandatory.