Is there a correlation between Gleason score and maximum standardized uptake value in locally advanced prostate cancer patients?

Abstract

68 Background: The aim was to assess the intensity of 68Ga-PSMA uptake in the primary tumour in patients locally advanced prostate cancer treated with definitive radiotherapy. Also correlation between the maximum standardized uptake value (SUVmax) of primary tumour and the Gleason score (GS) or prostate-specific antigen (PSA) level was assessed. Methods: The data of 201 biopsy-proven prostated cancer patients were retrospectively analysed. Median age of entire cohort was 68 years (range; 45 – 85 years). PET/CT images were analysed visually and semiquantitatively by measuring the SUVmax. The SUVmax of the primary tumour was assessed in relation to both PSA level and GS. Results: Median age of entire cohort was 68 years (ranged 45 – 85 years). Median PSA value at diagnosis was 20.3 ng/mL (ranged 2.1 – 301.0 ng/mL). Forty-two patients (23.9%) was in intermediate risk group, and 159 patients (79.1%) had high risk disease. Seventy two patients (36.8%) had regional lymph node metastasis. Median SUVmax of primary tumor and metastatic lymph nodes were 13.0 (ranged 1.3 - 84.3) and 12.6 (ranged 3.6 – 64.5), respectively. Patients with GS 7 or lower had significantly lower SUVmax compared to patients with GS > 7 (12.1±8.4 vs. 20.9±16.4; p < 0.001). However, there was no significant difference in SUVmax of tumors with GS of 3+4 and 4+3 (14.8±8.6 vs. 16.3±12.7; p = 0.6). Patients with PSA ≥10.0 ng/mL exhibited significantly higher uptake than those with PSA levels < 10.0 ng/mL (12.1±8.4 vs. 20.9±16.4; p < 0.001). SUVmax of intermediate risk patients was significantly lower than that of high risk patients (12.7±11.1 vs. 19.8±16.8; p = 0.01). In 72 patients with lymph node metastasis SUVmax was significantly higher compared to 129 patients without lymph node metastasis (24.9±21.3 vs. 14.7±10.6; p < 0.001). Conclusions: Tumours with GS 7 or lower, patients with PSAvalues ≤10 ng/mL, intermediate risk patients and patients without regional lymph node metastasis showed significantly lower 68Ga-PSMA uptake. 68Ga-PSMA-PET/CT should be preferentially applied for primary staging of prostate cancer in patients with GS > 7, PSA levels ≥10 ng/ml, high risk patients and patients with regional lymph node metastasis.