Utility of [11C]choline PET/CT in guiding lesion-targeted salvage therapies in patients with prostate cancer recurrence localized to a single lymph node at imaging: results from a pathologically validated series.

Objective: Positron emission tomography (PET)/computed tomography (CT) has been shown to be a valid tool in detecting lymph node (LN) metastases in men with biochemical recurrence after radical prostatectomy. We assessed its validity in detecting a single positive LN at pathologic examination in regard to an increasing interest in lesion-targeted salvage therapies.

Methods And Materials: We included 46 patients with biochemical recurrence after radical prostatectomy and a single positive spot at [(11)C]choline PET/CT who underwent pelvic or pelvic and retroperitoneal LN dissection. The ability of [(11)C]choline PET/CT in identifying the exact positive LN was assessed with the positive predictive value (PPV) in the overall population and according to androgen deprivation therapy, prostate-specific antigen value, and site of PET/CT positivity.

Results: Overall, 30 patients (65%) had positive LNs at pathologic examination. Of these, only 16 (35%) had pathologically confirmed metastases in the same lymphatic region and 11 (24%) had involvement of 1 single LN. Conversely, 28 patients had positive LNs in other areas and 8 had no evidence of metastases. The overall PPV of PET/CT was 34.8% and 23.9% when exact concordance was defined according to the lymphatic landing site and single positive LN, respectively. The PPV ranged from 33.3% to 44.4% and from 17.9% to 28.6%, in men with and without androgen deprivation therapy, respectively.

Conclusions: The PPV [(11)C]choline of PET/CT in correctly identifying patients with a single positive LN at salvage LN dissection is poor (24%). Therefore, extensive salvage treatment approaches are needed to maximize the chance of cure.