This study will evaluate a method to detect tumor cells that are circulating in the blood without getting a biopsy. The investigators already know from other studies that cancer tumors shed a small number of cells into the bloodstream every day. These are called circulating tumor cells (CTCs). Some early studies indicate the amount and type of CTCs in the blood can help determine the status of the tumor itself and the way it is responding to treatment. In this study, the investigators will compare the number of CTCs in the blood at different time frames before and after surgery to remove the prostate.

The investigators will collect a blood sample for the study when the participant has other blood tests drawn for their cancer treatment. The investigators will take one sample to check prostate specific antigen (PSA) levels and another blood sample for CTC analysis. The investigators will be drawing blood at the following time points: Screening; One day after surgery; 7-14 days after surgery; 3-6 months after surgery; at PSA recurrence or at two years.

Inclusion Criteria:

• Male
• 18 years of age or older
• Pathologically confirmed diagnosis of prostate adenocarcinoma
• Non-metastatic prostate cancer
• Planned radical prostatectomy at Massachusetts General Hospital

Exclusion Criteria:

• Patients must not have received prior radiation therapy, hormone therapy, or other medical therapy for prostate cancer prior to prostatectomy. Post-prostatectomy therapy at the discretion of the patient's treating physician(s) is allowed.
• Patients must not have metastatic prostate cancer
• No prior or current diagnosis of epithelial malignancy, except for skin cancer (squamous cell carcinoma or basal cell carcinoma)

Men with prostate cancer that will be undergoing prostatectomy at Massachusetts General Hospital