Diagnostic Imaging for Prostate Cancer

As one of the most common cancer types, the survival rates of patients with prostate cancer have increased with the emergence of novel therapies, over recent decades. Prediction and monitoring of response to therapy allow flexible selection of the ideal treatment strategy during the whole therapy process.

Diagnosis Approaches for Prostate Cancer

Prostate-Specific Antigen Blood Test

Prostate-specific antigen (PSA), a glycoprotein, is a unique multipurpose biomarker used in prostate cancer screening, diagnosis, staging, management of disease progression, and monitoring of treatment efficacy by non-invasive PSA density (related to prostate volume) test, PSA kinetics (PSA levels as a function over time) test, and the ratio evaluation of free PSA over total PSA. However, a prostate-specific antigen blood test has been critiqued, since it may miss some cases of cancer with a high false negative rate and it is unable to differentiate between aggressive and nonaggressive prostate cancer in clinical diagnosis.

Digital Rectal Examination

Digital rectal examination (DRE), an internal examination of the rectum, is a strong indication for the diagnosis of prostatic disorders, benign prostatic hyperplasia, and the four types of prostatitis, including acute prostatitis, chronic bacterial prostatitis, inflammatory or noninflammatory chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), and asymptomatic inflammatory prostatitis.

Prostate Biopsy

Transrectal ultrasound (TRUS) is the standard method for prostate cancer biopsies. Most prostate cancer cells in the peripheral zone are biopsied using a transrectal ultrasound-guided approach with at least 10 times core biopsies. If the prostate-specific antigen level is high and the doctor feels an abnormal area during a digital rectal exam, transrectal ultrasound can help to further diagnose for PC, which is a method of generating an image of organs in the pelvis. In the event of continued suspected PC, re-biopsy is indicated and preferably preceded with a multi-parametric Magnetic Resonance Imaging (mpMRI) scan.

Diagnostic Imaging for Prostate Cancer with RDC

Current Diagnosis Imaging Methods

Unfortunately, the current RECIST (Response Evaluation Criteria in Solid Tumors) via cross-sectional abdominopelvic imaging with CT (Computed Tomography) and MRI (Magnetic Resonance Imaging), shows limited diagnostic and predictive accuracy in this disease state. SPECT and PET imaging conducted by RDC (Radionuclide Drug Conjugate) becomes shows superior diagnostic performance compared with standard imaging allowing accurate response assessment in other tumor types as it enables imaging at the cell level with molecular processes in tissues.

Diagnostic Imaging for Prostate Cancer with ⁶⁸Ga-PSMA11

⁶⁸Ga-PSMA1, one of the most widely used RDC in diagnostic imaging in clinical, is applied in the diagnostic imaging of prostate cancer via PET, improving primary staging and the detection of biochemical recurrence in prostate cancer. ⁶⁸Ga-PSMA11 PET image of a 74-year-old patient with metastatic castration-resistant prostate cancer (mCRPC), one kind of prostate cancer, before the first ¹⁷⁷Lu-PSMA-617 RLT (Radioligand Therapy) in December 2015 demonstrates extended pelvic, abdominal, and thoracic lymph node metastasis shown as red markers in the Maximum Intensity Projection 3D image. After three cycles of RLT, the PSA (Prostate-Specific Antigen) level had significantly decreased.

Fig.1 ⁶⁸Ga-PSMA11 PET imaging before and after treatment. (Grubmüller, B., et al., 2019, Eur J Nucl Med Mol Imaging)

Reference

1. Grubmüller, B., Senn, D., Kramer, G., Baltzer, P., D'Andrea, D., Grubmüller, K. H., ... & Hartenbach, M. (2019). Response assessment using ⁶⁸Ga-PSMA ligand PET in patients undergoing ¹⁷⁷Lu-PSMA radioligand therapy for metastatic castration-resistant prostate cancer. European journal of nuclear medicine and molecular imaging, 46(5), 1063-1072.