Focal therapy is all about precision and accuracy. The more precise and accurate the diagnosis, the more precise and accurate the treatment can be. And the more precise and accurate the treatment, the better the outcomes in destroying cancerous tissue with minimal side effects. The good news for those seeking focal therapy is that technology is advancing in three areas that are aiding the pursuit of higher levels of precision and accuracy in both diagnostics and treatment.
Imaging & Reporting
The advances in imaging technology over the last decade cannot be overestimated and their impact has been led by no less significant advances in imaging techniques, expertise and reporting.
Since the publication of the PROMIS trial in 2017 and the wide reception to its evidence on the diagnostic efficacy of mpMRI studies of the prostate, 1.5T MRI scanners are widely available on the NHS, and calibrations for mpMRI studies of the prostate are increasingly understood and practiced. While the supply of expert uro-radiologosts is limited, there is well-defined software available to help and support radiologists in reading, interpreting and reporting on prostate MRI studies.. This involves identifying and contouring areas of interest, and traffic signalling to prioritise potential severity.
The continual development and adoption of PIRADs – Prostate Imaging Reporting and Data System – is contributing significantly to this process. The PIRADS score classifies MRI lesions on a scale from 1 to 5, which reflects their level of suspicion from least to most. PIRADS 3 lesions are considered equivocal.
Multiparametric magnetic resonance imaging (MRI) and MRI-directed biopsies using the PIRADS improves the detection of prostate cancers likely to cause harm, and at the same time decreases the detection of disease that does not lead to harms if left untreated. The keys to success are high-quality imaging, reporting, and biopsies by radiologists and urologists working together in multidisciplinary teams.
Reporting design is improving all the time and integrating critical imaging information, PIRADS, and in the best cases, contextual information including patient PSA and biopsy history. This enables efficient, comprehensive, and accurate communication between radiologist, urologist and other members of an MDT responsible for diagnostic and treatment decisions.
A good example of high-standard prostate MRI reporting has been set by Prostate Care Ltd, viewable here.
A number of researchers and organisations are working on applying machine learning to prostate tissue samples from biopsies in order to improve the accuracy and speed of pathology analysis and reporting. Still in early development, these efforts are continually improving and gaining acceptance.
Earlier this summer, a deep-learning system developed at Google outperformed general pathologists for Gleason grading of prostate cancer biopsies. In a validation set of 498 specimens that were positive for cancer, the deep-learning system came up with the same result as the panel of sub-specialists in 71.7% of cases, versus 58% for general pathologists, a statistically significant result. More on this study here.
Another team at the University of Pittsburgh set out to develop an algorithm that could more accurately identify prostate cancer. The team trained the tool on images from more than a million parts of stained tissue slides taken from patient biopsies. Each image was labelled by expert pathologists to teach the AI how to distinguish between healthy and abnormal tissue.
The algorithm was then tested on a separate set of 1,600 slides taken from 100 consecutive patients seen at University of Pittsburgh Medical Center (UPMC) for suspected prostate cancer.
During testing, the AI algorithm achieved 98 percent specificity and 97 percent sensitivity at detecting prostate cancer, which is significantly higher than previously reported for algorithms working from tissue slides. More on this study here.
While HIFU adoption continues apace, a new approach to applying ultrasound for focal therapy is emerging called TULSA. This approach uses transurethral ultrasound in place of focused ultrasound, and the key difference between it and HIFU is how ultrasound energy is applied to prostate tissue.
During HIFU prostate ablation, the ultrasound energy is focused through the rectal wall towards a specific location in the prostate. The heating pattern is referred to as a sonication. Many close or overlapping sonications are used to cover a specific region of the prostate. This technique can be used for small focused areas. The prostate tissue is therefore ablated from an ‘outside -in’ approach by delivering the focused thermal ultra-sound from the rectum inwards to the target region of prostate.
During the TULSA Procedure, thermal ultrasound is delivered directionally from a device within the urethra (there is no energy passed through the rectum) this device rotates and delivers heat in a sweeping pattern contacting a large volume of tissue in minimal time. The prostate tissue is therefore ablated from an ‘inside-out’ approach by delivering the directional, thermal ultra-sound from the urethra outwards to the edge of the target region of prostate.
The key benefits of the TULSA approach are higher levels of accuracy and reduced levels of damage to healthy tissue.
The Focal Therapy Clinic is actively engaged in each of these areas of technological development, and will update on progress regularly.