Abstract
PurposeTo assess the accuracy of [68Ga]-PSMA-11 PET/CT or [68Ga]-PSMA-11 PET/MRI (PSMA-11 PET/CT(MRI)) for lymph node (LN) staging using salvage LN dissection (SLND) in patients with biochemical recurrence (BCR) after radical prostatectomy (RP).Patients and methodsIn a prospective study, 65 consecutive patients who developed BCR after RP underwent SLND after PSMA-11 PET/CT(MRI) between 2014 and 2018. Extended SLND up to the inferior mesenteric artery was performed in all patients. Regional and template-based correlations between the presence of LN metastases on histopathology and whole-body PSMA-11 PET/CT(MRI) results were evaluated. The diagnostic accuracy of PSMA-11 PET/CT(MRI) was also evaluated in relation to PSA level at the time of SLND.ResultsThe median age of the patients at the time of SLND was 65 years (IQR 63–69 years) and the median PSA level was 1.4 ng/ml (IQR 0.8–2.9 ng/ml). Before SLND, 50 patients (77%) had additional therapy after RP (26.2% androgen-deprivation therapy and 50.8% radiotherapy). The median number of LNs removed on SLND was 40 (IQR 33–48) and the median number of positive nodes was 4 (IQR 2–6). LN metastases were seen in 13.8% of resected LNs (317 of 2,292). LNs positive on PSMA-11 PET/CT(MRI) had a median diameter of 7.2 mm (IQR 5.3–9 mm). Metastatic LNs in regions negative on PSMA-11 PET had a median diameter of 3.4 mm (IQR 2.1–5.4 mm). In a regional analysis, the sensitivity of PSMA-11 PET/CT(MRI) ranged from 72% to 100%, and the specificity from 96% to 100%. Region-specific positive and negative predictive values ranged from 95% to 100% and 93% to 100%, respectively.ConclusionPSMA-11 PET/CT(MRI) has a very good performance for the identification of LN metastases in patients with BCR after RP. The high diagnostic accuracy in the regional and subregional analyses demonstrates the potential of this approach to enable a region-directed instead of a complete bilateral therapeutic intervention. The performance of PSMA-11 PET/CT(MRI) is dependent on the PSA level and the size of the metastatic deposit.
Highlights
Despite effective local therapy with curative intent, about onethird of patients with localized prostate cancer (PC) experience biochemical recurrence (BCR) [1,2,3]
lymph node (LN) metastases were seen in 13.8% of resected LNs (317 of 2,292)
Metastatic LNs in regions negative on prostate-specific membrane antigen (PSMA)-11 positron emission tomography (PET) had a median diameter of 3.4 mm (IQR 2.1–5.4 mm)
Summary
Despite effective local therapy with curative intent, about onethird of patients with localized prostate cancer (PC) experience biochemical recurrence (BCR) [1,2,3]. While patients with distant metastases often require systemic therapy, those with locoregional failure are candidates for targeted locoregional salvage therapies with or without a limited course of androgen-deprivation therapy (ADT) [2, 6]. Locoregional therapy such as salvage radiotherapy or lymphadenectomy has been shown to result in potentially durable local and distant cancer control [7]. Contemporary reports indicate that approximately one-third of patients treated with radical prostatectomy (RP) do not receive a pelvic lymph node dissection (PLND) [8]. The frequency of “limited” pelvic LN metastases as a cause of BCR is expected to increase [8]
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