Interstitial Brachytherapy for the Treatment of Unresectable/Unablatable Kidney Cancer

PRIMARY OBJECTIVES: I. To determine the safety and feasibility of renal interstitial radiation therapy (interstitial brachytherapy). (Safety Lead-In) II. To evaluate local control of renal interstitial brachytherapy. (Expansion Phase) SECONDARY OBJECTIVES: I. To evaluate treatment response of the primary tumor. II. To evaluate 12 month distant progression free survival. III. To evaluate the 12 month volumetric growth of the primary tumor mass. IV. To determine biomarkers predicting response and resistance to radiation treatment. OUTLINE: Patients undergo interstitial brachytherapy for 1-2 fractions in the absence of disease progression or unacceptable toxicity. Patients who undergo 2 fractions may receive both fractions in the same day or on 2 separate days over 2 weeks. After completion of study treatment, patients are followed up every 3 months for at least 3 years.