One out of five men will be affected by prostate cancer. As with any cancer, early detection and treatment are key to survival. To effectively manage the disease, medical procedures such as radical prostatectomy, brachytherapy, cryotherapy, external beam radiation and hormone therapy offer more treatment options for patients. Brachytherapy, viewed by many as a technically sophisticated technique, offers a treatment for cancer while maintaining the quality of life. Published results support brachytherapy's role as one of the first line therapies for the treatment of prostate cancer. This year alone more than 60,000 men will receive permanent prostate seed implants.
Brachytherapy is defined as the use of radioactive materials in the treatment of cancer by placing radioactive sources in direct contact with the tissues to be treated.
The use of brachytherapy to treat prostate cancer dates back to 1911 when the use of radium inserted into the prostatic urethra via a catheter was first documented1. After significant complications and the advent of new treatments such as radical prostatectomy (prostate removal) and hormone therapy, clinicians lost interest in the technique.
In the early 1960's brachytherapy techniques were introduced again as clinicians experimented with the "retropubic technique". Patients underwent open surgical insertion of needles and seeds placed into the prostate by hand and eye guidance. Although many cases were performed and initial reports were favourable in terms of incidence of incontinence
and impotence, clinicians eventially abandoned the technique due to high failure rates. Research indicates that the failures were primarily due to inaccurate calculations of prostate volumes, inaccurate distribution of seeds , poor patient selection and suboptimal doses of radiation2. Twenty years later in the early 1980's , brachytherapy hit the medical radar for good as physicians in Denmark introduced the first closed transperineal implantation. As a direct result of advancements in transrectal ultrasound, perineal template guidance systems, treatment planning software, CT and Iodine-125 and Palladium-103 seeds and strands (radioisotope sealed sources), a modern era of prostate brachytherapy began.
Transrectal ultrasound and perineal guidance systems provided clinicians with a roadmap for the insertion of radioactive seeds. Under ultrasound guidance, needles could be moved through the prostate under constant visualisation, allowing for precise seed placement to ensure better results.
According to leading brachytherapist John C Blasko, MD, director of clinical research at Seattle Prostate Institute (Seattle, Wash..USA.) , "The breakthrough resulting in the renaissance in brachytherapy was the development of transrectal ultrasound. For the first time we were able to clearly see the prostate from outside the body. Transrectal ultrasound also provided a way by which needles could be accurately guided into the prostate through the perineum.
In this way needles and seeds could be accurately placed inside the prostate. Simultaneously, the development of computer technology enabled us to do sophisticated calculations of radiation doses to the prostate. These two develoments led to the birth of todays technique".
Since the 1980's clinical knowledge of brachytherapy has grown steadily. Advances in ultrasound technology, positioning and stabilizing equipment, computer software and the technique itself have improved brachytherapy's effectiveness and reduced complications of the procedure.
Screening for prostate cancer most commonly begins with prostate specific antigen (PSA) testing, digital rectal examinations and / or transrectal ultrasonography. Elevated levels of PSA may indicate the initial detection of pathology and a need for further examination such as ultrasound guided biopsy, the definitive method for diagnosing prostate cancer.
As an exceptional tool for diagnosing and staging prostate cancer transrectal ultrasound is valuable for guiding physicians during a prostatic biopsy. Use of a needle guide attached to the transducer allows physicians to follow on screen biopsy guidelines to quickly and precisely sample targetted areas.
" When patients with significantly elevated PSA undergo the customary transrectal biopsy of the prostate, roughly one third will have cancer, one third will be truly negative and one third will be falsely negative (i.e. negative on initial biopsies but ultimately proven to have cancer)," according to Winston E Barzell, MD, co-founder of Barzell-Whitmore , " This pool of patients with rising PSA and as yet undiagnosed cancer represents a vexing and numerically significant problem. Almost all of these difficult to diagnose prostate cancers can now be detected by a 'saturation' transperineal biopsy technique. This technique uses the brachytherapy template guidance model to systematically sample every area of the prostate, dramatically increasing the diagnostic yield of prostate biopsy".
In the event of a positive biopsy , the clinician grades (Gleason Score) and stages the tumour. Staging indicates the extent of the tumour, estimating the tumour size and location, and assists the clinician and patient in selecting appropriate treatment options. Men with early stage prostate cancer localised within the prostate are typically the best candidates for prostate brachytherapy, radical prostatectomy and external beam irradiation. Patients with more advanced disease may consider brachytherapy in combination with hormonal therapy and / or external beam irradiation or ultrasound guided cyrotherapy.
During the brachytherapy procedure a urologist uses ultrasound guidance to inject tiny radioactive seeds (Iodine-125 or Palladium-103 seeds) into the prostate through the template guidance system. To implant the seeds , the urologist implants seeds using implant needles through the perineum ( skin above the rectum) implanting the seeds anteriorly to posteriorly in the gland. High end equipment, such as the Brachyware products , permit physicians to perfectly align the ultrasound transducer for accurate imaging and fine tune the guidance mechanism required for precise seed placement.
Once implanted the seeds deliver high doses of radiation localized to the prostate, emitting radiation for up to several months . Using the brachytherapy technique, immediate potential side effects associated with radical prostatectomy, such as impotence and incontinence, are greatly reduced. Other advantages of brachytherapy over conventional treatments include ease of treatment, rapid return to normal activities, reduced chance of rectal injury and reduced radiation damage to surrounding healthy cells when compared to external beam radiation alone.
Two techniques currently exist for performing prostate brachytherapy: the "pre-planning technique" and the "real-time technique". In both methods a post operative CT scan is required to evaluate the post plan results, documenting seed placement and confirming the prescribed minimum radiation dose was achieved.
The pre-planning technique requires a detailed map of the prostate prior to surgery. A transrectal ultrasound volume study captures a series of prostate images designed to accurately describe the shape and volume of the prostate for treatment planning. Using specialized software, the data is analyzed and a three dimensional reconstruction of the prostate may be created. The transrectal study allows radiation oncologists and physicists to calculate an effective seed distribution
plan for treatment and order the correct number of seeds or strands.
Using Transrectal ultrasound, physicians complete a prostate volume determination and rendering of its spatial geometry. Based on these images, a plan for seed placement is created to achieve the desired radiation dose and dose pattern (dosimetry) to the prostate. During the implant every attempt is made to duplicate the pre-planned seed pattern in the patient. Although exact duplication is never accomplished, effective results are achieved routinely by experienced brachytherapists.
According to Dr John Blasko, " The key to a successful implant with the pre-plan method is an accurate volume study. This requires complete relaxation of the patient, for accuracy a stable, easily adjusted stepper and fixation devices and careful attention to patient positioning both during the volume study and in the operating room set up. With proper technique, the required minimum effective radiation dose and dose distribution goals can be achieved in all patients.
Ten year cure rates of 87 percent verify the pre-plan method can achieve excellent outcomes with minimum morbidity3.
The pre-plan approach minimizes expensive operating room time, permits accurate evaluation of possible pubic arch interference pre-operatively, provides time for detailed evaluation of numerous seed loading plans and allows accurate ordering of seeds".
The real -time planning technique, championed by Nelson N Stone,MD, clinical professor of Urology at Mount Sinai School of Medicine, New York, USA, requires only a preoperative sizing of the prostate. Seeds are ordered based on prostate size and radiation strength of the seeds. The detailed mapping and planning for seed implantation (dosimetry) is calculated using a nomogram calculation or computer planning software on site at the time of implantation.
According to Dr Stone " The real time technique has been found to be the most accurate method of placing seeds in the prostate4. This method eliminates the worry about matching a patients position to a pre plan and permits instantaneous adjustments in the operating room when the prostate gland moves".
"The primary advantage of the real-time technique is the ability to fit the seeding plan to the prostate anatomy as it is found at the time of the implantation, since there can be significant variability in the appearance of the prostate from that seen in the office" said Dr Whitmore.
SeeDOS Ltd is recognised as a supplier of specialized prostate brachytherapy equipment, including positioning and stabilizing devices. The extensive Brachyware product line includes top of the line stabilizing and positioning devices used in brachytherapy procedures around the world.
The Brachyware product line is designed to provide cutting edge technology for brachytherapy procedures. Our stabilizing, positioning and guidance devices form the most widely accepted systems for the treatment of prostate cancer via transperineal ultrasound-guided seed implantation. The Micro-Touch series of stabilizers and the new Brachystepper EX series of precision stepping devices are designed to handle every clinical demand.
Linked with a complete range of prostate brachytherapy procedure start up products this provides the ultimate brachytherapy package of products, available from SeeDOS, to assist you in the optimal application of this treatment technique.
In addition to high quality brachytherapy equipment new planning software will also play a role in the quality of prostate seed implants, ultimately resulting in better patient outcomes. The VariSeed 7.0 treatment planning software, available from SeeDOS, is an efficient tool for guiding clinicians through the brachytherapy planning and treatment process. The software allows radiation oncologists to create a volume study, a proposed plan and a complete post-plan as part of the implant process. With VariSeed's real time planning capabilities clinicians can overlay their pre-operative plans onto a live ultrasound image and adjust needles according to differences between the pre-operative plan and the actual implant. In addition the dose distribution can be displayed as it evolves on the real-time ultrasound view. The addition of dosimetry alerts enables clinicians to see where an implant may be deviating from the plan and make adjustments before the procedure is complete.
When interfaced to a tracked stepper, such as the Brachystepper EX, available from SeeDOS, this real time planning module allows clinicians to see the dosimetry develop as the seeds are implanted. Three dimensional dose displays and
user defined dosimetry alerts allow the clinician to have complete controlof the dosimetry before the procedure is complete. We believe this new capability will shorten the learning curve for physicians learning the procedure and improve the quality of implants.
In addition to the prostate, brachytherapy is currently being used to treat cancer in the breast, lung, cervix, oesophagus and pancreas. Research continues to indicate radioactive seed implants are as effective at killing cancer as alternative treatment options. Long term follow-up on patients receiving seed implants indicates a disease free survival rate of 90 percent.
New software and matching hardware technologies now are allowing a convergence of the pre-plan and real-time methods of brachytherapy. Detailed mapping of the prostate potentially can be performed in the office or the operating room in a matter of minutes, creating a detailed 3D map of the prostate. Sophisticated software can quickly calculate the ideal dosimetry. In the future we expect real-time dose and distribution calculations in the operating room to be continually updated at the time of implantation as the placement of each seed is visualized and scored in the planning software. With this technology, the final dosimetry or post-plan will be known in real-time and readily modified during the implant. This will revolutionize brachytherapy by eliminating the risk of a suboptimal implant that currently may be discovered only belatedly
on the post-operative CT scan.
With more than 10 years of excellent clinical results, transrectal ultrasound-guided prostate brachytherapy now is a treatment of choice for early stage prostate cancer.
For more information on brachytherapy procedures you can refer to a number of web sites covered under 'Useful Web Sites'.
1. A T Porter et al, "Brachytherapy for prostate cancer", CA-A Cancer Journal for Clinicians 45 (May/June 1995) 165-178.
2. H Ragde et al, " Interstitial iodine-125 radiation without adjuvant therapy in the treatment of clinically localised prostate carcinoma", Cancer 80 (August 1997) 442-453.
3. Grimm P, Blasko J, Sylvester JE, Meier RM, Cavanagh W. 10 year biochemical (prostate specific antigen) control of prostate cancer with I-125 brachytherapy. Int J Radiat Oncol Biol Phys. 2001; 51: 31-40.
4. Stock RG, Stone NN, Lo YC, Malhado N, Kao J, DeWyngaert JK: Post implant dosimetry for I-125 prostate implants: definitions and factors affecting outcome. Int.J.Rad.Oncol.Biol.Phys.2000; 48: 899-906.
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