Analysis of radiotherapy curative effect and prognostic factors in 164 patients with extracranial oligometastases

Objective: To investigate the efficacy of radiotherapy, as well as the prognostic factors of survival in patients with extracranial oligometastases. Methods: A total of 164 patients who underwent intensity-modulated radiotherapy (IMRT) of the extracranial oligometastases, from January 2013 to December 2016, were enrolled in the study. The short-term efficacy, local control rate, overall survival, progression free survival and adverse effects of treatment were observed. Results: Short-term efficacy was assessed within the first 1-3 months after the end of radiotherapy. The objective response rate (CR+PR) was 78.7% and the short-term efficacy is mainly related to the T stage of primary tumor (P = 0.004). Until the last follow-up, all patients with 1-, 2- and 3- year LC were 89.8%, 82.5% and 74.9% respectively. Univariate analysis showed that the influencing factors of LC include tumor size and gross tumor volume dose (all P < 0.05), multivariate analysis found no significant influence factors. The 1-, 2- and 3- year OS were 83.4%, 69.6% and 54.6% respectively. Univariate and multivariate analysis showed that the primary tumor sources, metastasis organs, whether synchronous or adjuvant chemotherapy and short-term efficacy were independent prognostic factors in patients of OS (P < 0.05 ). Main toxicity-associated events were grade 1-2 acute reactions, with only 6 patients experiencing grade 3 toxicity;no grade ≥ 4 toxic reactions or treatment-related deaths occurred. Conclusions: Radiation therapy for the treatment of extracranial oligometastases can achieve good curative effect, is well-tolerated and has low toxicity. (authors)