DIGITAL RECTAL EXAMINATION AND IMAGING STUDIES ARE UNNECESSARY IN MEN WITH UNDETECTABLE PROSTATE SPECIFIC ANTIGEN FOLLOWING RADICAL PROSTATECTOMY:

Radionuclide bone scintigraphy in patients with biochemical recurrence after radical prostatectomy: when is it indicated?

OBJECTIVE

To evaluate the use of radionuclide bone scintigraphy following biochemical recurrence after radical retropubic prostatectomy (RRP) for localized prostate cancer.

PATIENTS AND METHODS

Of 1197 patients undergoing RRP we identified those with biochemical recurrence and who had also had a bone scan. Biochemical recurrence was defined as a prostate specific antigen (PSA) level of > or = 0.4 ng/mL. Patients with indeterminate bone scan findings and those in whom the interval between the PSA test and the bone scan was >3 months were excluded. Patient age, PSA level and other relevant pathological details were recorded. Clinical symptoms at the time of bone scan, androgen deprivation after RRP, bone scintigram details and time to recurrence were documented.

RESULTS

Of the 1197 patients, 153 (12.8%) had a biochemical recurrence and 35 (23%) of these had a total of 44 bone scans taken over a mean (sd) follow-up of 70.4 (35.6) months; 34 (77%) bone scans were negative (group 1) and 10 (33%) positive (group 2). In group 1 the mean PSA at the bone scan was 5.2 ng/mL; 76% of the patients had a PSA of < 7 ng/mL. In group 2 the mean PSA at the bone scan was 30.7 ng/mL and all patients had a PSA of >7 ng/mL. The only significant difference between the groups was the PSA at the time of the bone scan (P < 0.001).

CONCLUSION

Bone scintigraphy is a sensitive diagnostic tool for detecting prostate cancer metastases to bone. A bone scan in patients with a serum PSA of <7 ng/mL on biochemical recurrence after RRP is unlikely to be positive, whereas a PSA of > or = 20 ng/mL is. The presence of skeletal symptoms or a PSA level of >7 ng/mL should prompt the clinician to obtain a bone scintigram.

Diagnosis of local recurrence after radical prostatectomy

In the long-term there is biochemical evidence of recurrent prostate carcinoma in approximately 40% of patients after radical prostatectomy (RP). Detecting the site of recurrence (local vs distant) is critical for defining the optimum treatment. Pathological and clinical variables, e.g. Gleason score, involvement of seminal vesicles or lymph nodes, margin status at surgery, and especially the timing and pattern of prostate-specific antigen (PSA) recurrence, may help to predict the site of relapse. Transrectal ultrasonography (TRUS) of the prostatic fossa in association with TRUS-guided needle biopsy is considered more sensitive than a digital rectal examination for detecting local recurrence, especially if PSA levels are low. Although it cannot detect minimal tumour mass at very low PSA levels (< 1 ng/mL) TRUS biopsy is presently the most sensitive method for detecting local recurrence. Nevertheless, the conclusive role of biopsy of the vesico-urethral anastomosis remains unclear. However, 111In-capromab pendetide scintigraphy and [11C]-choline tomography (which are better than conventional imaging for detecting metastatic tumour), have low detection rates for local disease and are considered complementary to TRUS in this setting. Patients with a high PSA after RP may be managed with external beam salvage radiotherapy. An initial PSA of < 1 ng/mL, Gleason score < 8 and radiation dose of 66-70 Gy seem to be key factors in determining success. Although a positive TRUS anastomotic biopsy may predict a better outcome after radiation therapy, the need to take a biopsy in the event of PSA failure remains under investigation. The value of salvage radiation to the prostatic bed for PSA-only progression after RP remains in question.