A paper by Ahmed et al published in the Lancet suggests a quarter of men suspected
of having prostate cancer could avoid potentially dangerous biopsies with the
help of MRI scans.
The authors did a
multicenter study and tested the diagnostic accuracy of Multi-parametric MRI (MP-MRI)
and Transrectal ultrasound guided prostate biopsy (TRUS-biopsy) against template
prostate mapping biopsy (TPM-biopsy). Men with prostate-specific antigen
concentrations up to 15 ng/mL, with no previous biopsy, underwent 1·5 Tesla
MP-MRI followed by both TRUS-biopsy and TPM-biopsy.
The researchers
enrolled 740 men, 576 of who underwent 1·5 Tesla MP-MRI followed by both
TRUS-biopsy and TPM-biopsies. Results from TPM-biopsy showed 408 (71%) of the men had cancer,
including 230 (40%) men with clinically significant cancer. When evaluating the 230 men with clinically significant cancer,
the MP-MRI had correctly diagnosed 93% of the aggressive cancers, whereas
TRUS-biopsy diagnosed only 48% as aggressive. This indicated that MP-MRI was
more sensitive than TRUS-biopsy (P < .0001). Of the 10 men with a negative MP-MRI scan,
nine (89%) had no cancer or a harmless cancer.
However, TRUS-biopsy had greater
specificity (96% vs. 41%) and positive predictive value (90% vs. 51%; P <
.0001 for both) than MP-MRI. Forty-four (5·9%) of 740 patients reported
serious adverse events, including 8 cases of sepsis following biopsy.
This study shows that using the two
tests could reduce overdiagnosis of harmless cancers by 5%, prevent one in four
men from having an unnecessary biopsy, and improve the detection of aggressive
cancers from 48% to 93%.
In conclusion given
that prostatic cancer which is the most common cancer in men with about 176,000
new cases and the cause of death in 27,000 patients in the United States in
2013, MP-MRI is a promising diagnostic test in the effort to reducing
over-diagnosis of clinically insignificant prostate cancers while improving the
detection of clinically significant cancers.
