Recurrent Gynecological Tumors in Previously Irradiated Patients. Does Re-Irradiation with Stereotactic Body Radiotherapy Have a Role? A Systematic Review

Background: Re-irradiation of patients with previously irradiated gynecological tumors represents one of the hot topics of modern oncology. It is generally performed using Brachytherapy (alone or after external beam radiation therapy (EBRT) re-treatment) or Stereo -tactic Body Radiotherapy (SBRT). Literature provides few data concerning SBRT re-irradiation (re-RT). Here we provided a statistical and comparative analysis of the studies to make a general assessment of the efficacy and reliability of SBRT, considering the potential benefits achievable in terms of local control, overall survival and toxicity. Methods: A computerized literature search was performed in 3 electronic databases (MEDLINE, EMBASE, and Cochrane) from 1996 to 2020. Only studies analysing outcomes of re-irradiated (re-I) patients were taken into consideration. Quality assessment score and risk of bias were assessed for each article. Random-effects models were used due to great subjectivity given the lack of related control groups in the non-comparative studies and a tendency towards high heterogeneity (examined by the Cochran Q chi-square test and the I2 statistic). To determine the pooled 2-year Overall Survival (OS) and 2-year Local Control (LC) and >Grade 3 (G3) treatment-related toxicities, an established meta-analysis technique over single and multi-arm studies was performed. Results: Of 21 articles focusing on the role of SBRT in recurrent gynaecological cancers, were identified. Only 7 articles, published between 2009 and 2020, with outcomes limited to re-I patients and specific radiotherapy techniques were included. The selected studies counted a total of 196 patients, 157 of whom were previously irradiated. With a median follow up time of 14.5 months, using SBRT re-I technique, the pooled 2-year OS of 52.7% (95% confidence interval (CI): 0.372 to 0.651) and 2-year LC of 75.7% (95% CI: 0.614 to 0.852) were observed. SBRT re-irradiation technique does not affect toxicities with pooled >G3 late toxicities being 8.7% (95% CI: -0.0944 to 0.267). Conclusions: According to our review, SBRT re-irradiation technique seems to be feasible and safe, when brachytherapy re-RT technique is not available. Further studies are warranted to standardize the best radiation therapy in recurrent gynaecological cancer.