• Status post radical prostatectomy for histologically confirmed adenocarcinoma of the prostate

• pathologically confirmed T1-T3 disease

• no sign of lymph node or metastatic disease

• pT1-pT3pNxMx patients in whom standard NCCN or AUA guidelines would suggest are at low risk for pelvic lymph node or metastatic disease and who would not require confirmatory imaging for metastatic disease. This includes patients with Gleason 6 or 7(T2 disease) and PSA less than 20.

• Eastern Cooperative Oncology Group(ECOG) status 0-2

• adequate renal and liver function as well as bone marrow reserve (measured serum creatinine \<2mg/dl, bilirubin ≤ 1.5 mg/dl, ANC ≥ 1.5 x 10 (3) uL, platelets ≥ 50 x K/uLL, and hemoglobin ≥ 10 g/dL)

• 30-80 y/o at time of diagnosis with a life expectancy of \>= 3 yrs

• focally positive surgical margins are permitted

• no plan to receive adjuvant hormone or radiation therapy

• PSA at the time of enrollment must be undetectable

• life expectancy of 3 years