Up to 79% preservation of potency and less than 2% incontinence are the striking results of a clinical study in which over 300 men received an innovative treatment for prostate cancer.
HDR (high dose rate) brachytherapy in combination with an innovative new image-guidance technology was shown to be just as effective as conventional therapies, but much less likely to cause the common side-effects of impotence and incontinence.
Standard treatments for prostate cancer are surgery (prostatectomy) to remove the prostate, and radiotherapy. Normally, radiotherapy is delivered from an external source situated at a distance (a process known as teletherapy or external beam therapy), and is therefore directed over the entire prostate area. This makes it virtually impossible to avoid penetrating healthy tissue, including the sensitive urethra running through the middle of the prostate, and the neurovascular bundles (on either side at the base of the prostate) that control penile function. After surgery or conventional teletherapy, between 40-100% of men will be left impotent, and 35% of surgery patients will suffer incontinence.
In brachytherapy, on the other hand, the tumour is irradiated from the inside. In prostate cancer therapy, this is achieved by introducing small tubes into the prostate at specific points, and then inserting a radioactive isotope either temporarily (HDR) or permanently (tiny implants) into each tube to deliver the appropriate dose.
Until recently, the precision of HDR brachytherapy was determined by positioning of the tubes based on CT imaging. However, CT scans tend to produce indistinct images of the prostate. Furthermore, the images have to be taken after rather than during the tube insertion, and so can prove inaccurate as the position of the prostate and other internal organs adjacent to it may move.
A new technology to further improve the precision of HDR brachytherapy was therefore developed by a multidisciplinary team of Radiation Oncologists and Medical Physicists together with Nucletron, a leading manufacturer of radiotherapy equipment and software. The real-time image-guidance technology that they created has now made it possible to view crucial aspects of the procedure in real time, rather than relying on past images. This means that clinicians can view the position of the organs, check whether the tubes are following the right insertion pathways, and amend the dose to more accurately target the tumour while avoiding vulnerable areas.
The outcome of the study featuring this new technology, comprising over 300 patients, was announced last week at the 12th International Conference on Optimal use of Advanced Radiotherapy on Multimodality Oncology in Rome. The study itself was performed by Professors Zamboglou, Tunn and Baltas from the University Hospital in Offenbach, Germany. By uniting a multidisciplinary team of urologists, radiation oncologists and clinical physicists working closely together, they were able (and continue) to achieve excellent results with minimum side-effects.
With a radiation source inside rather than outside the body, there is no need to penetrate healthy tissue in order to reach the target. As Professor Nikolaos Zamboglou from Offenbach comments, "Conventional prostate cancer radiotherapy involves treating the tumour from the outside in. But you get far fewer side-effects if you treat it from the inside out. And with this new imaging technology, we can really hit the spot."
It was shown that HDR brachytherapy in combination with the live image-guidance technology makes it easy to monitor both the tumour and adjacent organs during treatment. Nucletron's innovative technology enables a combination of on-line tracking, guidance and possible adaptive interventions to be used. The team is able to make intermediate adaptations when required, for example by re-imaging the patient and adjusting the dose before each treatment session, "Often, it is this interventional option that can make the difference", Professor Zamboglou confirms.