Stage Information for Prostate Cancer
Detection of asymptomatic metastatic disease in prostate cancer is greatly affected by the staging tests performed. Radionuclide bone scans are currently the most widely used tests for metastases to the bone, which is the most common site of distant tumor spread. Magnetic resonance imaging (MRI) is more sensitive than radionuclide bone scans but is impractical for evaluating the entire skeletal system. Some evidence suggests that serum prostate-specific antigen (PSA) levels can predict the results of radionuclide bone scan in newly diagnosed patients. In one series, only 2 of 852 patients (0.23%) with a PSA of less than 20 �g/L had a positive bone scan in the absence of bone pain. In another series of 265 prostate cancer patients, 0 of 23 patients with a PSA of less than 4 ?g/L had a positive bone scan, and 2 of 114 patients with a PSA of less than 10 ?g/L had a positive bone scan. Prognosis is worse in patients with pelvic lymph node involvement.
Whether to subject all patients to a pelvic lymph node dissection (PLND) is debatable, but in patients undergoing a radical retropubic prostatectomy, the nodal status is ascertained as a matter of course. In patients who are undergoing a radical perineal prostatectomy in whom the PSA value is less than 20 and the Gleason sum is low, however, evidence is mounting that a PLND is probably unnecessary, especially in patients whose malignancy was not palpable but detected on ultrasound.[3,4] A PLND remains the most accurate method to assess metastases to pelvic nodes, and laparoscopic PLND has been shown to accurately assess pelvic nodes as effectively as an open procedure. The exact role of PLND in diagnosis and subsequent treatment is being evaluated, though it has already been determined that the length of hospital stay following laparoscopic PLND is shorter than that following an open procedure. The determining factor when deciding if any type of PLND is indicated is whether definitive therapy may be altered. Likewise, preoperative seminal vesicle biopsy may be useful in patients with palpable nodules who are being considered for radical prostatectomy (unless they have a low Gleason score) because seminal vesicle involvement could affect choice of primary therapy and predicts for pelvic lymph node metastasis.
In patients with clinically localized (stage I or stage II) prostate cancer, Gleason pathologic grade and enzymatic serum prostatic acid phosphatase values (even within normal range) predict the likelihood of capsular penetration, seminal vesicle invasion, or regional lymph node involvement. Analysis of a series of 166 patients with clinical stage I and stage II prostate cancer undergoing radical prostatectomy revealed an association between Gleason biopsy score and the risk of lymph node metastasis found at surgery. The risks of node metastasis for patients grouped according to their Gleason biopsy score was 2%, 13%, and 23% for Gleason scores of 5, 6, and 8, respectively.