Interstitial Brachytherapy for the Treatment of Unresectable/Unablatable Kidney Cancer

This study is testing interstitial brachytherapy — a procedure where radioactive seeds are placed directly inside a kidney tumor through the skin — as a treatment for kidney cancer in patients who cannot or will not have surgery, and whose tumors also cannot be treated by standard ablation techniques. **You may be eligible if:** - You have kidney cancer confirmed by biopsy - Your tumor is between 4 and 10 cm in size - Your tumor is mostly solid (at least 80% solid) and has been growing over at least 6 months - You are not a candidate for or are unwilling to have surgery - Your tumor cannot be reliably treated with standard ablation - You have not received prior treatment for kidney cancer - You are in good general health (ECOG less than 2) - You have adequate blood, liver, and kidney function **You may NOT be eligible if:** - Your cancer has spread to lymph nodes or distant organs - You are pregnant - You have an active autoimmune or inflammatory condition - You have a coagulation or bleeding disorder that would make the procedure unsafe Talk to your doctor to see if this trial is right for you.