Interstitial Brachytherapy for the Treatment of Unresectable/Unablatable Kidney Cancer

Inclusion Criteria: * Elected to undergo interstitial brachytherapy as part of conventional treatment for renal cell carcinoma * Biopsy proven renal cell carcinoma * No definitive evidence of locally advanced (nodal or tumor thrombus) or distant (metastatic) disease * Lesion size (maximal dimension) of 4 to 10 cm * Patient not a candidate for curative surgery (unwilling or unable to pursue surgery) * Lesion cannot be reliably treated with ablative techniques * Entire lesion able to be treated adequately by brachytherapy per radiation oncologist * Tumor predominantly solid (\~ \> 80%) * Lesion that has been observed for \>= 6 months with demonstrable growth rate anticipated to be \>= 4 mm/year by same imaging modality * Renal tumor that is amenable to percutaneous access for interstitial renal brachytherapy (Institutional Review Board \[IRB\]) * Hemoglobin \> 9 * Absolute neutrophil count (ANC) \>= 1500/uL (microliter) * Platelets \>= 100,000/uL * Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) =\< 3.0 upper limit of normal (ULN) * Total bilirubin =\< ULN * A competent immune system * Estimated glomerular filtration rate (eGFR) \>= 30 * Good performance status (Eastern Cooperative Oncology Group \[ECOG\]) \< 2 * Understanding and willingness to provide consent * No prior systemic treatment for kidney cancer * Women of childbearing potential must have negative pregnancy test at start of therapy Exclusion Criteria: * Presence of an active, untreated, non-r…