Evaluation of the early value of 68Ga-PSMA PET/CT for radical prostatectomy / 中华泌尿外科杂志

ABSTRACT

Objective:To evaluate the value of 68Ga-labeled prostate-specific membrane antigen( 68Ga-PSMA PET/CT)in the diagnosis of prostate cancer(PCa) and determination of the strategy on neurovascular bundle(NVB)preservation and lymphadenectomy before surgery. Methods:We retrospectively analyzed the clinical data of 46 patients with newly diagnosed PCa who underwent 68Ga-PSMA PET/CT from June 2018 to October 2019. The median age was 66.50 (60.00, 69.25) years old and the median PSA was 15.97(8.58, 33.10)ng/ml. Forty-one patients were diagnosed PCa and 5 were diagnosed with benign prostatic hyperplasia or prostatitis by 68Ga-PSMA PET/CT, 6 were diagnosed with lymph nodes metastasis. Forty patients underwent mpMRI, 33 were diagnosed PCa, and 6 were diagnosed with lymph nodes metastasis. Seventeen patients underwent 11C-choline PET/CT, 12 were diagnosed PCa, and 4 were diagnosed with lymph nodes metastasis. Among the 41 patients which were diagnosed PCa by 68Ga-PSMA PET/CT, 26 were confirmed with PCa by needling biopsy, 12 did not undergo the needling biopsy and 3 had negative biopsy; 22 were in the high-risk group, and 19 were in the low- and medium-risk group. All 41 patients underwent radical prostatectomy. The strategy of NVB preservation was determined by the position of the PCa reported by 68Ga-PSMA PET/CT. If the tumor was close to the unilateral prostate capsule, the healthy part of the NVB would be preserved. And if the tumor was limited in the prostate gland, bilateral NVB would be preserved. The NVB was preserved in 16 cases(6 cases unilateral and 10 cases bilateral). In addition to routine lymph node dissection for patients in the high-risk group, lymph node dissection was also performed on patients with 68Ga-PSMA PET/CT that showed positive lymph nodes in the low- and medium-risk groups. The paired chi-square or Fisher exact test was used to compare the sensitivity and specificity of 68Ga-PSMA PET/CT, mpMRI, and 11C-choline PET/CT for lesion detection. Spearman analysis was used to examine the correlation between the SUV max, Gleason score, and the PSA value before treatment. Results:Forty-one patients undergoing radical resection were diagnosed PCa by postoperative pathology, and no cancer tissue was observed at the surgical margin; the median Gleason score was 8(7, 9); 20 cases (48.8%) had a pathological stage ≤pT 2c; 21 cases (51.2%)≥pT 3; 7 cases were N+ (11 positive lymph nodes). Seven cases (17.1%) had complications of Clavien-Dindo ≤ grade 2 within 30 days after surgery, and there was no complication above grade 3 after surgery. The median follow-up time of the 41 patients was 16(12, 20). The rate of urinary control was 46.3%, 95.1%, and 100% after 1 month, 6 months, and 12 months follow-up respectively. Among the five patients that did not undergo surgery, the PSA value of 4 decreased after antibiotic treatment, and biopsy was performed in 1 case without PSA decreasing, and no carcinoma was found. The sensitivity of 68Ga-PSMA PET/CT on the primary PCa was 100%(41/41), which was significantly better than that of 11C-choline(80%, 12/15, P=0.016)and mpMRI (83.7%, 31/37, P=0.009), while no statistical significance was observed between the specificity of 68Ga-PSMA PET/CT (5/5)and 11C-choline PET/CT(2/2, P=1.000), 68Ga-PSMA PET/CT and mpMRI(1/3, P=0.107). Of the 41 patients that were diagnosed with PCa, the sensitivity of 68Ga-PSMA PET/CT to lymph nodes metastases(71.4%, 5/7) had a significant difference with that of mpMRI(16.7, 1/6, P=0.016), but no statistical difference with 11C-choline (75%, 3/4, P=1.000). Analysis of the relationship between SUV max of 68Ga-PSMA PET/CT, Gleason score, and PSA value before treatment revealed that the SUV max of 68Ga-PSMA PET/CT in patients with Gleason score ≥8 and <8 score were 19.60(9.58, 24.38) and 8.55 (5.18, 12.88); SUV max of patients with PSA values ≥20 ng/ml and <20 ng/ml before treatment were 19.40 (13.00, 23.50) and 8.40 (5.35, 13.95), respectively, the differences were statistically significant (all P<0.05). Conclusions:68Ga-PSMA PET/CT had high sensitivity and specificity for the diagnosis of primary prostate cancer lesions, but the sensitivity for the diagnosis of lymph node metastasis was not enough to guide the preoperative decision of whether to remove the lymph node and the scope of the removal. However, the treatment strategy of whether to retain NVB could be formulated according to the tumor location displayed by 68Ga-PSMA PET/CT before surgery.