Preliminary application of ¹⁹²Ir high-dose rate brachytherapy in postoperative recurrent colorectal cancer with intrapulmonary oligometastases

Objective: To investigate the efficacy and feasibility of ¹⁹²Ir high-dose rate brachytherapy for recurrent intrapulmonary oligometastasis after colorectal cancer surgery. Methods: Patients from May 2013 to October 2017 with intrapulmonary oligometastasis after colorectal cancer surgery in Cangzhou Integrated Traditional Chinese and Western Medicine Hospital were enrolled. A total of 15 lesions were obtained from 10 patients, which were treated with CT-guided high dose rate of ¹⁹²Ir. The implant needles were inserted into the tumor and were adjusted to appropriate positions under the guidance of CT. Then the images after transplanting were uploaded to the planning system to delineate the target area and the organ at risk volume. Patients underwent a single radiation dose of 20 Gy. Results: All 10 patients were successfully treated. Grade 1 adverse events were observed for 30% of patients. Of the 10 patients, one patient had a mild cough, and two had bloody sputum. There was no serious adverse events occurred. The local control rate (LC) of the patients at 1 year after treatment was achieved in 93.3%. Only one developed local advancement after six months, who received the secondary brachytherapy. The median progression-free survival (PFS) was 8.5 months and the median overall survival (OS) was 14.7 months. Conclusions: High dose rate brachytherapy is effective in terms of recurrent lung metastases after surgery for colorectal cancer, with a moderate rate of adverse reactions and a favorable local tumor control rate. (authors)