Combining Imaging Techniques Could Enable Surgical Removal of Prostate Cancer Without Biopsy

By MedImaging International staff writers
Posted on 15 Nov 2024

Image: MRI prostate-specific membrane antigen PSMA PET-CT) and hematoxylin & eosin staining imaging of three representative cases (Photo courtesy of Professor Nianzeng Xing. DOI: 10.1097/CM9.0000000000003204)

Prostate cancer (PCa) is one of the most prevalent cancers in men. Traditionally, PCa is diagnosed through biopsy, where a small tissue sample is collected from the affected area using imaging methods, such as ultrasonography. However, ultrasound-guided prostate biopsy has poor sensitivity, often leading to the detection of clinically insignificant PCa. Moreover, the use of transrectal ultrasound-guided prostate biopsy can be costly and comes with risks, such as urinary tract infections. A biopsy is usually required before recommending radical prostatectomy (RP), a common surgical procedure to remove the prostate gland in PCa patients.

To address these challenges, researchers are working on alternatives that could eliminate the need for biopsy prior to RP. Imaging techniques like multiparametric magnetic resonance imaging (mpMRI), which uses magnetic fields and radio waves, and prostate-specific membrane antigen positron emission tomography (PSMA PET) combined with computed tomography (CT), which uses radioactive tracers and X-ray imaging, have proven diagnostic value for PCa. In PSMA PET/CT, the presence of cancer is assessed based on the maximum standardized uptake value (SUVmax), indicating the amount of radioactive tracer absorbed by cancer cells. Previous studies have shown that combining PSMA PET/CT with MRI can reduce the likelihood of missing clinically significant PCa cases (false negatives)

Building on these findings, researchers from the Chinese Academy of Medical Sciences (Beijing, China) investigated whether PSMA PET/CT combined with MRI could help patients with suspected PCa avoid biopsy prior to undergoing RP. The study included 56 patients with PCa who had RP without a preoperative biopsy, recruited from two tertiary hospitals between December 2017 and April 2022. The agreement between clinical diagnoses and pathological findings was evaluated. Patients with elevated prostate-specific antigen levels or abnormal results from a digital rectal examination were recommended to undergo mpMRI. Positive mpMRI results were defined as having a Prostate Imaging Reporting and Data System (PI-RADS) score of 4 or higher. Similarly, PSMA PET/CT results were considered positive when the SUVmax value was 4 or greater. Only patients with elevated prostate-specific antigen levels, positive mpMRI results, and positive PSMA PET/CT findings, who opted not to have a biopsy, were considered for the biopsy-free approach.

Among the 56 patients who underwent RP, pathological analysis confirmed PCa in 55 cases, with 49 of these patients diagnosed with clinically significant PCa. One case was misdiagnosed as high-grade prostatic intraepithelial neoplasia (HGPIN). The prostate-specific antigen levels and SUVmax values in patients with clinically significant PCa were higher than in those with clinically insignificant PCa or HGPIN. Additionally, the median prostate volume was lower in patients with clinically significant PCa. Extracapsular extension was accurately detected in 21 of 26 patients, while five patients were mistakenly classified as having localized disease. When the SUVmax cutoff was raised to 7.5 or higher, PSMA PET/CT's diagnostic accuracy for clinically significant PCa reached 100%. These results, published in the Chinese Medical Journal, suggest that combining PSMA PET/CT with MRI could enable a biopsy-free approach to RP in patients with PCa.

“This diagnostic technique is a boon for patients to decrease the medical costs and hospitalization duration and avoid complications associated with biopsy,” said Dr. Nianzeng Xing from the Chinese Academy of Medical Sciences who led the study.