External beam radiotherapy
External beam radiotherapy has a role in the management of prostate cancer for:66
- localised/locally advanced prostate cancer where the individual has at least a 10-year life expectancy and has been assessed as suitable by the multidisciplinary team
- clinically localised prostate cancer with evidence of similar progression-free survival in low-risk individuals treated with radical prostatectomy or radiotherapy
- post-operative individuals who are likely to relapse or who have had a biochemical relapse
- treatment with neoadjuvant ADT
- individuals with metastatic disease requiring palliation.
Radiotherapy techniques have evolved allowing higher doses and improved treatment accuracy which have been associated with improved disease outcomes and reduced treatment effects.63 Current approaches available for prostate cancer include:47
- three dimensional (3D) conformal radiation therapy
- intensity modulated radiotherapy
- image guided radiotherapy.
An integral aspect of radiotherapy planning involves identifying individuals with high and intermediate risk cancers who will benefit from pelvic lymph node irradiation and neo adjuvant and adjuvant androgen deprivation therapy (ADT).40
External beam radiotherapy in the management of prostate cancer:40, 64
- Results in temporary adverse effects in up to 50% of men, including diarrhoea, tenesmus, proctitis, dysuria, frequency, and lethargy.
- Is associated with long-term effects including erectile dysfunction and chronic proctitis.
Contraindications for radiotherapy for prostate cancer include:63
- prior pelvic irradiation
- active inflammatory disease of the rectum
- permanent indwelling Foley catheter.
Relative contraindications include:63
- very low capacity bladder
- chronic moderate or severe diarrhoea
- bladder outlet obstruction requiring a suprapubic catheter
- inactive ulcerative colitis.
Brachytherapy involves insertion of a radioactive source directly into the prostate gland providing a dose of radiation locally, thus sparing surrounding normal tissue.44, 65 The radioactive sources may be permanently placed seeds containing a low dose isotope such as iodine-125, cesium-137 or palladium-103, or temporary cables or wires (inserted through percutaneous catheters) to deliver high-dose radiation (iridium 192).44, 65
Permanent Low Dose Rate (LDR) Seed Brachytherapy
Permanent seed brachytherapy slowly emits localised radiation to the prostate gland and, over time, gradually loses radioactivity. Adequate dose levels of treatment to the prostate are achieved with reduced irradiation of the bladder and rectum.63
Permanent seed brachytherapy can be performed as a sole modality. When used in combination with external beam radiotherapy, with or without hormonal therapies, complication rates increase with its use.40, 66 Permanent radioactive seed implantation as a sole modality is recommended for individuals with:40
- stage cT1b-T2a N0, M0
- a Gleason score less than or equal to 6 assessed on an adequate number of random biopsies
- an initial PSA level less than or equal to 10ng/mL
- less than or equal to 5-% of biopsy cores involved with cancer
- a prostate volume of less than 50cm3
- an International Prostatic Symptom Score (IPSS) less than or equal to 12.
The recurrence-free survival after 5 and 10 years has been reported to range from 71% to 93% and from 65% to 85%, respectively.31
Pre-operative bowel preparation and imaging facilitates the implant procedure and potentially decreases post-operative morbidity.66 Imaging allows determination of the number and placement of seeds to be used.66
Approximately 100-150 radioactive seeds or more are inserted between the scrotum and the anus by needles with TRUS guidance.67 The advantage of permanent radioactive seed implantation is that, as an outpatient or overnight procedure, treatment is completed in one day.40
Potential complications may include acute urinary retention, as well as irritation to the urethra which may persist for a year after implantation and may be associated with frequency, urgency, hesitancy, dysuria, decreased flow of stream, nocturia, and incontinence.40, 44, 64-66
Bowel symptoms are typically minimal and may include proctitis, constipation or diarrhoea and rectal bleeding.66 The rate of erectile dysfunction after seed implantation has been reported between 30%-53%.68, 69 The development of erectile dysfunction may be progressive over several years.40 Common effects on sexual function include bloody ejaculate for several weeks post-implant, discoloured, diminished or dry ejaculate, and temporary oligospermia.66
Men need to be reassured that none of their body fluids are radioactive and only the seeds emit radiation. There is a small risk of radiation exposure to others and the precautions recommended depend on the isotope used. Iodine-125 requires greater restrictions than Palladium-103.66 Principles of radiation safety should therefore be implemented, including:66
- avoiding prolonged, close-proximity contact with children and pregnant women for two months post-seed insertion
- using condoms during sexual intercourse for one month post-seed insertion.
Temporary High Dose Rate (HDR) Brachytherapy
Temporary high dose rate (HDR) prostate brachytherapy involves delivery of localised radiotherapy via radioactive sources placed through the previously inserted catheters via a computer controlled remote after-loader machine.24, 66 The catheters are implanted under a general or spinal anaesthetic via a transperineal approach under guidance of TRUS or MRI.39, 67
Several treatments are delivered over an interval of 24-36 hours; typically two daily treatments administered six hours apart.66 HDR prostate brachytherapy may be given in combination external beam radiotherapy.64, 66 HDR prostate brachytherapy is recommended for individuals with intermediate risk disease demonstrating:24, 66
- clinical stages of T1b to T3b
- no evidence of distant metastases
- a Gleason grade 8-10
- a PSA of less than 30
- only one high risk feature present in individuals with high risk disease
- no history of trans-urethral resection of the prostate (TURP)
- suitability for general or spinal anaesthetic.
Minor bleeding, bruising and tenderness of the perineal area may occur.66 Potential complications include irritation to the urethra, which results in dysuria and lower urinary tract symptoms (irritative), nocturia, urinary retention and haematuria.64, 66 The risk of developing impotency has been reported between 10-60%.64, 66
Access current clinical guidelines and summarise the indications for external beam radiotherapy and brachytherapy in the management of prostate cancer.
Identify potential short and longer term adverse effects of external beam radiotherapy and brachytherapy for prostate cancer.
Describe interventions for assessing and managing the following short term effects related to external beam radiotherapy:
- Skin irritation
- Burning on urination.
Outline how you would apply principles of radiation safety in the care and education of a man receiving permanent seed prostate brachytherapy.