Prostate-specific membrane antigen PET-CT in patients with high-risk prostate cancer before curative-intent surgery or radiotherapy (proPSMA): a prospective, randomised, multicentre study - The Lancet
Summary
Background
Conventional imaging using CT and bone scan has insufficient sensitivity when staging
men with high-risk localised prostate cancer. We aimed to investigate whether novel
imaging using prostate-specific membrane antigen (PSMA) PET-CT might improve accuracy
and affect management.
Methods
In this multicentre, two-arm, randomised study, we recruited men with biopsy-proven
prostate cancer and high-risk features at ten hospitals in Australia. Patients were
randomly assigned to conventional imaging with CT and bone scanning or gallium-68
PSMA-11 PET-CT. First-line imaging was done within 21 days following randomisation.
Patients crossed over unless three or more distant metastases were identified. The
primary outcome was accuracy of first-line imaging for identifying either pelvic nodal
or distant-metastatic disease defined by the receiver-operating curve using a predefined
reference-standard including histopathology, imaging, and biochemistry at 6-month
follow-up. This trial is registered with the Australian New Zealand Clinical Trials
Registry, ANZCTR12617000005358.
Findings
From March 22, 2017 to Nov 02, 2018, 339 men were assessed for eligibility and 302
men were randomly assigned. 152 (50%) men were randomly assigned to conventional imaging
and 150 (50%) to PSMA PET-CT. Of 295 (98%) men with follow-up, 87 (30%) had pelvic
nodal or distant metastatic disease. PSMA PET-CT had a 27% (95% CI 23–31) greater
accuracy than that of conventional imaging (92% [88–95]
vs 65% [60–69]; p<0·0001). We found a lower sensitivity (38% [24–52]
vs 85% [74–96]) and specificity (91% [85–97] vs 98% [95–100]) for conventional imaging
compared with PSMA PET-CT. Subgroup analyses also showed the superiority of PSMA PET-CT
(area under the curve of the receiver operating characteristic curve 91% vs 59% [32%
absolute difference; 28–35] for patients with pelvic nodal metastases, and 95% vs
74% [22% absolute difference; 18–26] for patients with distant metastases). First-line
conventional imaging conferred management change less frequently (23 [15%] men [10–22]
vs 41 [28%] men [21–36]; p=0·008) and had more equivocal findings (23% [17–31]
vs 7% [4–13]) than PSMA PET-CT did. Radiation exposure was 10·9 mSv (95% CI 9·8–12·0)
higher for conventional imaging than for PSMA PET-CT (19·2 mSv
vs 8·4 mSv; p<0·001). We found high reporter agreement for PSMA PET-CT (κ=0·87 for nodal
and κ=0·88 for distant metastases). In patients who underwent second-line image, management
change occurred in seven (5%) of 136 patients following conventional imaging, and
in 39 (27%) of 146 following PSMA PET-CT.
Interpretation
PSMA PET-CT is a suitable replacement for conventional imaging, providing superior
accuracy, to the combined findings of CT and bone scanning.
Funding
Movember and Prostate Cancer Foundation of Australia.
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