Comparison of clinical efficacy and complications of 125I seed brachytherapy and stereotactic body radiation therapy for recurrent pulmonary metastases from colorectal carcinoma

Purpose
To evaluate the efficacies of 125I seed implantation and stereotactic body radiation therapy (SBRT) in treatment of recurrent lung metastases from colorectal cancer, to compare the tolerance of lung tissue to both forms of radiotherapy, and to analyze the factors that affect the prognosis.

Material and methods
According to treatment received, thirty colorectal cancer patients with post-operative lung metastases were separated into two groups: 125I seed implantation group (group A; n = 16) and SBRT group (group B; n = 14). Patients were followed up, and local control rate, survival, and post-operative complications were analyzed retrospectively. Kaplan-Meier method was used for survival analysis. Cox proportional hazards model was used to identify the independent predictors of poor prognosis.

Results
Survival was significantly different between group A and group B (median survival, 15 months and 11.5 months, respectively; p = 0.015). Local control rates at the first, third, sixth, and twelfth months after treatment were all > 80%, with no significant difference between the two groups (p = 0.829). Significant differences were seen between the two groups in the number of treatments received (p = 0.009) and the incidence of radiation pneumonitis (p < 0.001) as well as radiation-induced pulmonary fibrosis (p = 0.005). On multivariate regression analysis radiation pneumonitis was an independent predictor of poor prognosis (HR = 3.356, 95% CI: 1.518-7.421; p = 0.003).

Conclusions
125I seeds brachytherapy and SBRT are both effective for control of lung metastases but the former causes milder lung tissue damage. It can be repeated after short intervals, and appears to be a safe and efficient treatment for lung metastases.