Biopsy in Prostate Cancer. More Is Better.

Take-Away Points

• ■ Major Focus: For patients with prostate cancers visible at MRI, combining both MRI-targeted and systematic prostate biopsies results in approximately 10% more cancer diagnoses, approximately a third of which are clinically significant compared to either method alone.

• ■ Key Result: With the combined approach, there is less upgrading to clinically significant carcinoma (< approximately 4%) compared to MRI targeted biopsy (approximately 9%) and systemic biopsy (approximately 17%), suggesting that the combined approach gets closer to actual histologic grade and is less likely to result in overtreatment or undertreatment.

• ■ Impact: The combined biopsy method gets closer to real precision medicine with better diagnostic certainty.

Detecting and grading of clinically significant prostate cancer are used to guide patient management. Goals include avoiding both undertreatment of high-risk disease and overtreatment of low-grade tumors with low risk of prostate cancer–specific death. Systematic, nontargeted biopsy using 12 cores is currently the most common method for tissue diagnosis and grading of prostate cancer. In this case, US is commonly used to visualize the gland but not tumor since US on its own has low accuracy for prostate tumor detection. Recently, multiparametric MRI has demonstrated utility for prostate tumor detection and is being used to guide tumor biopsy, sparking debate that MRI or MRI/US fusion may replace systematic biopsy. Starting in 2007, Ahdoot et al accrued adult men with elevated prostate-specific antigen or palpable abnormality who had a lesion visible at MRI and consented to undergo biopsy. A total of 2103 patients underwent prostate MRI and biopsy with MRI-targeted and systematic methods, 404 of whom subsequently underwent prostatectomy with histologic validation of imaging findings.

The cancer detection rate was 52.5% with systematic biopsy and 51.5% with MRI-targeted biopsy alone but increased to 62.4% for the combined technique. MRI-targeted biopsy led to more diagnoses of higher-grade disease than systematic biopsy. Adding targeted to systematic biopsy increased cancer detection by almost 10% of which 28% were clinically significant and upgraded disease in 22%. However, systematic biopsy alone detected clinically significant disease in 9%. For the prostatectomy group, upgrading and clinically significant upgrading of disease stage occurred in rank order of systematic biopsy, then MRI-targeted biopsy, and then combined, showing that either biopsy method alone has relatively high diagnostic uncertainty compared to combined. Downgrading of clinically significant carcinoma occurred more commonly with combined biopsy (4%) with smaller, but comparable frequencies for systematic and MRI-targeted groups.

Several prior studies suggested MRI-targeted biopsy outperforms systemic biopsy in detecting clinically significant prostate cancer, but none demonstrated that the latter can be completely omitted. The current study found that the combined approach increases the number of cancer diagnoses and improves likelihood of biopsy being predictive of true pathologic grade. Exclusion of one biopsy type may lead to underdetection and less accurate stratification in groups and has the potential to translate into over- or undertreatment.

Highlighted Article

• Ahdoot M, Wilbur AR, Reese SE, et al. MRI-targeted, systematic, and combined biopsy for prostate cancer diagnosis. N Engl J Med 2020;382(10):917–928. doi: 10.1056/NEJMoa1910038