A Phase II Study of Cyberknife Radiosurgery for Renal Cell Carcinoma

Inclusion Criteria:

* Participants must meet the following criteria on screening examination to be eligible to participate in the study:
* Participants must have histologically or radiological evidence of Stage I (T1N0M0) renal cell carcinoma with a size no larger than 8 cm in greatest dimension measured by MRI or CT Scan
* At least one (usually up to 3) gold fiducial placed in or around tumor, can be performed on the same day - after signing research informed consent.
* No irreversible coagulopathies
* Age ≥ 18 years old because no dosing or adverse event data are currently available on the use of Cyberknife Radiosurgery radiation in participants \<18 years of age, children are excluded from this study but will be eligible for future pediatric Phase II trials.
* ECOG Performance Status ≤2 (Appendix A).
* At least 12 month life expectancy
* Ability to have CT and/or MRI imaging with or without contrast and must be performed within 120 days prior to registration.
* No other cancer in previous 2 years with the exception of non-invasive skin cancers
* All subjects meeting eligibility criteria irrespective of gender, minority or other underrepresented status will be eligible for enrollment into the study.
* The effects of Cyberknife Radiosurgery on the developing human fetus are unknown. For this reason and because Radiation is known to be teratogenic, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately.
* Ability to understand and the willingness to sign a written informed consent document and study specific consent form prior to study entry.
* Labs: Serum Creatinin \<3 mg/dl, Urinalysis, INR \<2, PTT \<70 sec, AST, ALT ≤2.5x ULN, Abnormalities on urinalysis (i.e. proteinuria) will not exclude patients from participation on study.

Exclusion Criteria:

* Participants who exhibit any of the following conditions at screening will not be eligible for admission into the study.
* Irreversible coagulopathies that preclude fiducial placement
* Prior upper abdominal external beam irradiation
* Prior history of invasive malignancy within the last 2 years
* Inability to deliver target dose with CyberKnife due to inability to image fiducials
* Inability to deliver target dose with CyberKnife due to normal tissue dose constraints
* Inability to have contrast CT or MRI to help define tumor volume for radiation planning
* Decreased platelet count and / or anticoagulation parameters that would preclude transcutaneous placement of fiducials