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Prostate cancer overview > Surgery for Prostate Cancer > Prostate Brachytherapy > Electroporation for Prostate Cancer – Early Clinical Trials
Dr Lyn Oliver AM PhD
Retired Medical Physicist
Modern healthcare technology for radiation therapy of prostate cancer has a significantly improved the quality of treatment.
Introduction
The technology used for prostate cancer radiation therapy has improved markedly in recent times. The treatment machine can more accurately target the prostate with the X-ray beam.
The Accuracy Problem
The prostate position inside the patient’s pelvis can change from day-to-day. The amount of urine in the bladder, faecal content in the bowel and gas in the rectum can slightly change the position of the prostate. To ensure the prostate cancer is totally eradicated, its X-ray dose should be as high as practicable. But the surrounding normal critical structures should receive as little X-ray irradiation as possible because of their radiation sensitivity. Excessive dose to the rectum can cause long-term complications for the patient.
With inadequate daily pre-treatment techniques to determine the patient’s prostate and other critical structures, the problem was that:
- the maximum prostate dose was limited to avoid X-ray complications of the rectal wall;
- the treatment fields were made larger than necessary to allow for small daily variations in position of the prostate; and
- patient cure rates and quality of treatment were compromised.
The Accuracy Solution
But using the latest imaging techniques to view before every treatment where the prostate is, the radiation therapists can adjust the treatment set-up to target the prostate. The new technique enables:
- the prostate cancer tissues be treated to a higher radiation dose;
- smaller beams that can more easily miss treating the sensitive tissues of the rectal wall and other organ structures; and
- significantly improve patient cure rates combined with a better-quality treatment.
The Royal Australian and New Zealand College of Radiologists (RANZCR) published this YouTube video, October, 2014:
Targeting Cancer Radiation Therapy
The video provides a description of the treatment steps involved.
The radiation therapist uses a special computer program to precisely ‘plan’ the position, direction and dose for each small beam treated each day. The staff individually tailor the plan for each patient prior to commencing their first treatment. The radiation oncologist prescribes each patient’s treatment. Your doctor inspects and approves the plan before the treatment course commences and monitors your medical condition as treatment progresses.
Modern Radiation Therapy Techniques
For an excellent coverage of modern radiotherapy techniques used for a wide range of cancers, you can visit the RANZCR website
External Beam Radiation Therapy (EBRT)
Image-Guided, Intensity Modulated Radiation Therapy (IMRT)
- If you choose external radiation beam therapy of the prostate, then your treatment centre should be using the most recent modern technique of image-guided radiation therapy for treatment by an intensity modulated high energy beam (IMRT).
- As previously mentioned, IMRT significantly reduces the risk of the radiation damage to the rectal wall tissues. The rectum is located very close behind the prostate. Also, bowel irregularities (such as diarrhoea) during the course of IMRT should not occur (as it often did using the previous ‘older’ method of treatment).
- By avoiding rectal complications, the image-guided radiation therapy and IMRT method to direct the X-ray beam through all angles, the technique is able to deliver a higher dose of radiation and improve prostate cancer cure results.
- External beam radiotherapy normally requires receiving daily treatment for approximately 5 weeks (weekends excluded). The treatment is painless and quick. But travelling to and from the hospital and waiting for treatment each day over five weeks can be exhausting.
- Patients who have had surgical prostatectomy have regular PSA tests for some years after the operation. The PSA should be zero after the prostate is surgically removed,
- But, if the PSA test shows an increase after prostatectomy, then it is a sign that there’s some residual prostate cancer cells remaining. The surgeon will advise the patient how further treatment may proceed.
- A survey of prostatectomy patients showed that approximately 1 in 4 of these patients had represented with a raised PSA count within 2 years after their surgery. The surgeon referred them to radiation therapy for follow-up treatment.
- Prostatectomy patients, referred to radiotherapy for further treatment, receive X-ray beam treatment using the same advanced IMRT technique to irradiate the pelvic bed. This is to ‘kill’ any residual cancer cells that may remain in surrounding pelvic bed tissue structures.
- For patients who receive external beam radiation therapy, it does not cause immediate erectile dysfunction. But the radiation can cause long term deterioration of the erectile nerves leading to earlier than normal loss of your sexual ability.
World First Prostate Targeting Trial
One of the latest and greatest world trials is in progress in Sydney at Royal North Shore Hospital.
Imaging techniques show that the prostate can move small distances during treatment. Gas in the bowel and urine in the bladder is the cause of the prostate movement.
After more than 10 years research and development work, Professor Paul Keall (Medical Physicist, Sydney University) has succeeded in designing and developing the instrumentation to monitor prostate movement and make corrections of the linear accelerator treatment beams during each exposure. The Radiation Oncology Department at Royal North Shore Hospital. organised the final work on this project.
The new technique is called ‘targeted prostate therapy’ .
It’s explained in a NSW Press Release:
Future Advantages of Targeted Radiation Therapy
Targeted radiation therapy was initially developed for prostate cancer treatment. But the tracking technique will make a significant improvement for many other body sites.
Clinical trials have already begun for the treatment of lung tumours. The treatment beam can follow the tumour movement caused by the patient breathing during the X-ray beam treatment.
By continually targeting a moving tumour volume to this level of accuracy, future advantages for specific treatment sites would be:
- make tighter, smaller and given a much higher dose to treatment volume;
- less treatment complications of toxicities to normal tissue structures;
- fewer visits for treatment;
- lower costs for the patient and Health system;
- decreased workload on radiation therapy equipment services; and
- decreased cancer patient waiting times for a course of radiation therapy.
Lyn Oliver AM PhD, 7 May 2017
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