In the prospective paired-cohort CADMUS study reported in The Lancet Oncology, Grey et al found that patients at risk of prostate cancer had a similar likelihood of being diagnosed with clinically significant cancer with the use of multiparametric ultrasound vs multiparametric magnetic resonance imaging (MRI). Some cancers were missed by both tests, but more were missed with ultrasound.
As noted by the investigators, “Multiparametric MRI of the prostate followed by targeted biopsy is recommended for patients at risk of prostate cancer. However, multiparametric ultrasound is more readily available than multiparametric MRI.”
Study Details
The multicenter study included 306 patients with an elevated prostate-specific antigen concentration or abnormal findings on digital rectal examination who underwent both multiparametric ultrasound and multiparametric MRI between March 2016 and November 2019. Patients with positive findings (Likert score ≥ 3) on either test underwent targeted biopsy, with masking of test results. If both tests were positive, the order of targeting at biopsy was randomly assigned.
The co-primary endpoints were: proportion of positive lesions on, and agreement between, MRI and ultrasound in identifying suspicious lesions (Likert score of ≥ 3); and detection of clinically significant cancer, defined as Gleason score of ≥ 4 + 3 in any area or a maximum cancer core length of ≥ 6 mm of any grade (PROMIS definition 1), in patients who underwent biopsy.
Key Findings
Among the 306 patients, 257 underwent prostate biopsy.
<ul> <li>Multiparametric ultrasound detected 4.3% fewer clinically significant prostate cancers than multiparametric MRI, but it would lead to 11.1% more patients being referred for a biopsy.</li> <li>Multiparametric ultrasound could be an alternative to multiparametric MRI as a first test for patients at risk of prostate cancer, particularly if multiparametric MRI cannot be carried out.</li> <li>Both imaging tests missed clinically significant cancers detected by the other, so the use of both would increase the detection of clinically significant prostate cancers compared with using each test alone.</li> </ul>— Grey et al
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Ultrasound was positive (Likert score ≥ 3) in 272 patients (89%, 95% confidence interval [CI] = 85%–92%) and MRI was positive in 238 patients (78%, 95% CI = 73%–82%), with a difference of 11.1% (95% CI = 5.1%–17.1%). Fifty-eight patients were positive on ultrasound alone, 24 on MRI alone, and 214 on both; 10 patients were negative on both tests. Positive test agreement was 73.2% (95% CI = 67.9%–78.1%).
Any cancer was detected in 133 (52%, 95% CI = 45.5%–58%) of 257 patients undergoing biopsy, with 83 (32%, 95% CI = 26%–38%) having clinically significant disease on PROMIS definition 1. Among the patients undergoing biopsy, ultrasound detected PROMIS definition 1 cancer in 66 (26%, 95% CI = 21%–32%) and MRI detected PROMIS definition 1 cancer in 77 (30%, 95% CI = 24%–36%), with a difference of –4.3% (95% CI = –8.3% to –0.3%).
The combination of both tests detected all 83 clinically significant cancers on PROMIS definition 1. Of these, 60 were detected by both tests, 6 (7%, 95% CI = 3%–15%) were detected by ultrasound and missed by MRI, and 17 (20%, 95% CI = 12%–31%) were detected by MRI and missed by ultrasound (agreement = 91.1%, 95% CI = 86.9%–94.2%). Among the 257 patients undergoing biopsy, ultrasound detected 36 (14%) and MRI detected 44 (17%) clinically insignificant cancers on PROMIS definition 1.
The investigators concluded, “Multiparametric ultrasound detected 4.3% fewer clinically significant prostate cancers than multiparametric MRI, but it would lead to 11.1% more patients being referred for a biopsy. Multiparametric ultrasound could be an alternative to multiparametric MRI as a first test for patients at risk of prostate cancer, particularly if multiparametric MRI cannot be carried out. Both imaging tests missed clinically significant cancers detected by the other, so the use of both would increase the detection of clinically significant prostate cancers compared with using each test alone.”
Hashim U. Ahmed, FRCS, of the Department of Surgery and Cancer, Imperial College London, is the corresponding author for The Lancet Oncology article.
Disclosure: The study was funded by The Jon Moulton Charity Trust, Prostate Cancer UK, University College London Hospitals Charity, and Barts Charity. For full disclosures of the study authors, visit thelancet.com.
