Prostate Cancer Diagnosis
Read about the differences between standard and fusion biopsy procedures and discover why Fusion Bx is better for your business.
Standard Biopsy Limitations
Systematic biopsies have an average cancer detection rate of only 20%.1 Traditionally men suspected of prostate cancer are given systematic biopsies performed under ultrasound image guidance. Ultrasound imaging is insufficient for identifying suspicious cancer regions so clinicians end up taking 12-15 random samples. As a result, the cancer is either missed entirely, or if detected, is difficult to determine the extent and severity. This leads to under treatment of men with serious disease and overtreatment of men with indolent disease.
Detection of clinically significant cancer depends on two factors:
1. Accuracy- how close to the truth a diagnostic test is
2. Reliability- how reproducible a test is
Low – blind systematic biopsies sample less than 1% of the prostate.
Prostate cancer is multifocal and microscopic. Detecting it requires sampling at least a few cancerous cells in 10- 12 cores. It requires high specificity; you need to know where the cancer is and more importantly, where it is not.2 The prostate remains the only organ where a blind sampling technique is standard practice. This is due to the poor visibility of cancer in 2D TRUS images and limited anatomical context to guide needles to suspicious locations in the 2D TRUS plane.3 Despite these complications, most men are offered a standard TRUS biopsy based on an elevated PSA level or an abnormal DRE.4
Tumor locations are easily misclassified as the needle angle is oblique to the posterior surface. Only the site of entry is recorded, even though the needle may sample more than 1 region. Oversampling can lead to detection of clinically insignificant cancers, repeat biopsy and overtreatment, while undersampling can miss clinically significant cancers as a result of sampling the periphery of a tumor with a low Gleason score. This inaccuracy, inherent to TRUS biopsies, has resulted in an undergrading of disease in a considerable proportion of patients. Interestingly, increasing the number of cores marginally increases diagnostic yield. It has not been shown to effectively reduce the risk of undersampling. Instead, it further escalates the potential of identifying small indolent cancers as well as cost. As men are becoming more aware of the realities of overdiagnosis and overtreatment, both physicians and patients are warming up to active surveillance as an option for low risk tumors. Adopting active surveillance as a primary treatment method introduces additional constraints on current biopsy techniques. It requires accurate localization of clinically significant tumors so that it may be regularly and consistently surveyed.1
Radiology and Urology Go Together
Magnetic Resonance Imaging (MRI) offers an alternative diagnostic pathway in men with a clinical suspicion of cancer. MRI could be used as a triage test to avoid biopsy if the results are negative, whereas positive results could be used for targeting regions of interest during biopsy. Studies like the PRECISION trial show that MRIs with or without targeted biopsies resulted in fewer unnecessary biopsies, a higher detection rate of clinically significant cancers, and a decrease in the identification of clinically insignificant cancers, all requiring less biopsy cores than standard TRUS.4
Fusion Biopsy Workflow
MRI provides an action plan for fusion biopsy.
Why Fusion Bx?
"Fusion Bx was easily adopted by our clinic. Now, fusion biopsies are a part of our weekly routine."
- Dr. Winston Barzell, 21st Century Oncology, USA
Increased Detection Rates
The Fusion Bx produces higher cancer detection rates by addressing three key sources of inaccuracy during biopsy procedures:
1. Prostate Deformation
- Inconsistent pressure during the procedure leads to target error
- Freehand systems make it difficult to apply consistent pressure
- Focal’s semi-robotic arm prevents target errors by ensuring consistent pressure on the prostate
2. Patient Motion
- Patient discomfort increases motion
- Focal’s semi-robotic arm allows the probe to pivot at patient’s sphincter for maximum comfort
- Automatic motion compensation accounts for minor movements
- Rigid only approach does not account for changes in shape and size of the prostate between image acquisition and biopsy procedure
- Prostate deformation can occur during procedure due to contact with probe
- Focal’s approach combines both rigid and non-rigid (elastic) methods:
- Rigid: Easily identifiable landmarks are used to align images in all three planes
- Non-rigid: A few simple contours are used to automatically segment the entire prostate and deform each slice
Fusion Bx 2.0 is available for sale in the United States, Canada, and Hong Kong
1 Bjurlin MA, Taneja SS. Standards for prostate biopsy. Curr Opin Urol. 2014;24(2):155-61.
2 Wei, JT. Limitations of a contemporary prostate biopsy: the blind march forward.Urol Oncol. 2010;28(5):546-9.
3 Harvey CJ, Pilcher J, Richenberg J, Patel U, Frauscher F. Applications of transrectal ultrasound in prostate cancer. Br J Radiol. 2012;85 Spec No 1 (Spec Iss 1):S3-17.
4 Kasivisvanathan, Veeru, et al. MRI-Targeted or Standard Biopsy for Prostate-Cancer Diagnosis. New England Journal of Medicine. 2018; 378(19):1767–77. doi:10.1056/nejmoa1801993.