Positive Findings on 18F-fluciclovine PET/CT in Patients with Suspected Recurrent Prostate Cancer and PSA levels ≤ 0.5 and ≤ 0.3 ng/ml

Abstract

Listen

Translate article

Conventional imaging studies rarely identify anatomic sites of disease in men with biochemically recurrent prostate cancer after local therapy and a low PSA (≤ 0.5 ng/ml). Limited data have explored the utility of 18F-fluciclovine positron emission tomography/computed tomography (PET/CT) in this population. We evaluated the positivity rate (PR) of 18F-fluciclovine PET/CT in men with prostate cancer with suspicion for recurrence after therapy and PSA value ≤ 0.5 and ≤ 0.3 ng/ml. We performed a retrospective cohort study of men with suspected recurrent prostate cancer who underwent 18F-fluciclovine PET/CT from August 2016 to September 2017 at our institution. Men with known pre-scan PSA were included. Men who received prior hormonal therapy were excluded due to the potential confounding of the pre-scan PSA and scan findings. PR overall and based on anatomic region(s) of involvement (local [L], regional [R], local and regional [L+R], para-aortic lymph nodes [PA], and other distant metastases [DM]) were evaluated for men with prescan PSA value (ng/ml) of ≤ 0.5. This was compared to the PR of men with PSA of > 0.5 to ≤ 1 and > 1. The PR and anatomic region(s) of involvement for patients with PSA ≤ 0.3 were evaluated as a subgroup of the ≤ 0.5 group to explore the utility in men with very low PSAs. The impact of PSA group on PR was determined using the Chi-square test. A p-value < 0.05 was considered statistically significant. Overall, 101 men met selection criterion. Thirty of 101 men had a PSA ≤ 0.5 (median 0.25, interquartile range [IQR] 0.20-0.36) and 20/30 men had a PSA ≤ 0.3 (median 0.23, IQR 0.17-0.25). Thirteen of 101 men had a PSA > 0.5 to ≤ 1 (median 0.74, IQR 0.67-0.80), and 58/101 men had a PSA > 1 (median 4.22, IQR 2.46-7.32). The table describes 18F-fluciclovine PET/CT PR overall and based on anatomic region. PSA group was associated with PR (p < 0.001). Although men with PSA ≤ 0.5 had a lower PR compared to the higher PSA groups, 16/30 (53%) men had a positive scan. Among them, 12/16 (63%) had pelvic or extrapelvic findings (3 R, 3 L+R, 2 PA, and 4 DM). In the subgroup analysis of men with PSA ≤ 0.3, 11/20 (55%) men had a positive scan and 8/11 (73%) men had pelvic or extrapelvic findings (2 R, 2 L+R, 2 PA, and 2 DM). Over half of men with PSA ≤ 0.5 and ≤ 0.3 ng/ml after initial treatment for prostate cancer will have positive findings on 18F-fluciclovine PET/CT suggesting that even at very low PSAs, this test may identify local, regional, or distant sites of recurrence and could be used to help identify potential sites of disease and guide management. Further investigation of the clinical impact of this is ongoing.Abstract 1001; TablePSA groupNOverallL onlyR onlyL+R onlyPA onlyOther DM≤ 0.32011 (55%)3 (15%)2 (10%)2 (10%)2 (10%)2 (10%)≤ 0.53016 (53%)4 (13%)3 (10%)3 (10%)2 (7%)4 (13%)> 0.5 ≤ 1139 (69%)4 (31%)2 (15%)1 (8%)1 (8%)1 (8%)>15855 (95%)21 (36%)7 (12%)6 (10%)6 (10%)15 (26%) Open table in a new tab