Histological verification of ¹¹C-choline-positron emission/computed tomography-positive lymph nodes in patients with biochemical failure after treatment for localized prostate cancer

OBJECTIVES: To evaluate the potential of ¹¹C-choline-positron emission tomography (PET)/computed tomography (CT) for planning surgery in patients with prostate cancer and prostate-specific antigen (PSA) relapse after treatment with curative intent. PATIENTS AND METHODS: We retrospectively reviewed the charts of 10 patients with PSA recurrence after either external beam radiation (two) or radical retropubic prostatectomy (eight) for prostate cancer, and who had a laparoscopic lymphadenectomy for suspicious lymph nodes detected on ¹¹C-choline-PET/CT. The histological results and PET/CT findings were compared. RESULTS: In all, 22 suspicious lymph nodes were found on PET/CT, and 14 on conventional CT or magnetic resonance imaging. Comparing the conventional imaging showed concordance in 13 lymph nodes. Three of the 10 patients had no metastatic lymph node disease on definitive histology. The mean (sd) PSA level for these patients was 1.0 (0.4) ng/mL, whereas that in patients with lymph node metastases was 15.1 (9.2) ng/mL (statistically significant difference, P < 0.05). The positive predictive value was seven of 10. All of the patients initially regressed, with PSA increases after lymphadenectomy. Two of the patients are being managed by watchful waiting, two had radiotherapy of the prostate fossa and two had chemotherapy with docetaxel. Four patients were treated by hormone-deprivation therapy. After a mean (sd) follow up of 11 (7) months, one patient died, one has PSA progression, but none of those with negative histology has clinical signs of local recurrence. CONCLUSIONS: ¹¹C-choline-PET is a valuable tool for detecting recurrent prostate cancer, but the limited positive predictive value should lead to a critical interpretation of the results.