Brachytherapy (the term is derived from the Greek word brachys,
which means brief or short) refers to cancer treatment
with ionizing radiation delivered via radioactive material placed a short distance from, or within, the tumor. Thus, brachytherapy is also known as internal beam radiation therapy.
Two types of brachytherapy are practiced to treat prostate cancer, named permanent low dose brachytherapy and temporary high dose brachytherapy. Patients with organ confined prostate cancer (localisedcancer) can be effectively treated with brachytherapy alone. However, additional management strategies like hormonal ablation or short exposure to external beam radiation may also be used in combination to brachytherapy. Click to Enlarge U
American Joint Committee on Cancer defines a suitable candidate for brachytherapy as a prostate cancer
patient with stage T1-T2 cancer, patient whose PSA (prostate specific antigen) levels are equal to or less than 10 ng/ml or the patient with biopsy grade of Gleason score lower than 7.
Prostate cancer patients with high risk of developing extra-prostatic extension can be considered for brachytherapy, but in combination with supplemental IMRT (intensity modulated radiation therapy) which is a form of external beam radiotherapy (EBRT). Patients with Gleason score of 7 or more, PSA levels of10 ng/ml or more, and tumor stage higher than T2b are considered at high risk of developing extra-prostatic cancer.
Brachytherapy is never considered for patients with prostate glands larger than 60 grams. However, oncologists instilbrachytherapy in patients with gland size up to 60 gms after downsizing it using hormonal ablation therapy.
The hormone therapy
reduces the size of gland by 25-40% and therefore aids in treating the patient with brachytherapy. However a pilot study in the year 2007 published in an international Brachytherapy Journal, found that patients undergoing brachytherapy following hormonal ablation of gland are at high risk of developing acute urinary retention and dysuria (painful urination). Brachytherapy is contraindicated in Patients with the following conditions:
- Distant spread or metastasis of prostate cancer
- Life expectancy of less than 5 years
- Previous transurethral resection of the prostate (endoscopic surgery to cut away a part of prostate gland to reduce the size)
- Pubic arc interference (the bones of pubic area interfere with insertion of surgical probes or needles)
- Extensive obesity (layers of fat interfere with insertion of surgical probe or needle)
Both the forms of brachytherapy are minor surgical procedures and requires and can be done under spinal or general anesthesia. Imaging techniques like trans-rectal ultrasound or CT scan or MRI guides the surgeon to precisely locate the tumor and therefore plan the surgery.
What is Permanent or Low-Dose Brachytherapy?
This approach of Brachytherapy is also known as seed-implantation brachytherapy which uses radioactive seeds or pellets made of radioactive materials like iodine-125 or palladium-103. The radioactive seeds are inserted through small probes using a skin template between scrotum and anus and inside prostate. The needles are then removed while seeds are left inside the gland. The radioactive seeds emit low doses of radiation for weeks or months. The important characteristic of such seeds is that the radiations emitted by them can travel up to a small distance only. This allows for maximum radiation exposure to the affected area while reducing the possibility of radiation toxicity to the surrounding normal tissues. Generally, 40-100 radioactive seeds or pellets are inserted inside the cancerous prostate gland, which can cause minor discomfort to the patient during routine activities. The procedure is possible as a day case without admission to the hospital.The most recent research by German Cancer Society (2015) found that brachytherapy with iodine-125 alone in patients with localized prostate cancer provides five- year disease free survival in 93% patients with adverse events like mild to moderate proctitis in only 16-19% patients.
The treatment was also found to cause extremely low levels of urinary complications like incontinency, high frequency, urination while sleeping, and feeling of incomplete bladder emptying in 59% patients. The therapy proved to increase life quality of most of the patients.
Reports in International Journal of Radiation Oncology provides promising outcomes for patients at high-risk of developing metastatic prostate cancer (PSA level of more than 20ng/ml) when treated with low dose brachytherapy in combination with hormonal ablation or external beam radiotherapy.
What is Temporary or High-Dose Brachytherapy?
The procedure is called temporary brachytherapy since the radioactive material is removed out of the patientís body after completion of the therapy unlike permanent seed implant brachytherapy
. Hollow needles are first inserted between the area of scrotum and anus and inside the prostate gland. Soft and flexible nylon tubes (catheters) are then passed inside the needles. The needles are then removed in a manner that the catheter stays inside the patientís body. Radioactive material is then passed in to these catheters. For the purpose of high dose radiation administration, radioactive iridium-192 and cesium-137 are selected. The radioactive material is kept inside the catheter for five to fifteen minutes and then removed out. The procedure is repeated for 2-3 times over two days of hospital stay. Catheter is removed only after last radiation treatment. Patient may experience itching, pain and swelling near scrotum and anus for a week after the treatment. Many patients also observe reddish brown urine due to some blood in urine.
Mostly, for the treatment of prostate cancer, high dose brachytherapy is given in combination to low doses of external beam radiation therapy. Brachytherapy is considered to boost the effectiveness of external radiotherapy. This combination treatment is a lengthy procedure and is completed in 4-5 weeks. Research suggests that patient treated with combination of high dose brachytherapy and EBRT experiences a disease free survival period of 5.3 years as compared to 4.3 years by the patients treated only with EBRT.
However, this data is only applicable to patients with localised prostate cancer. No conclusive research is available which observes the effectiveness of high dose brachytherapy and EBRT
combination in intermediate and high risk patients.
Conventionally, only the combination plan has been used by the radiation oncologists. However, recent findings are advocating the use of only high dose brachytherapy (monotherapy) for treating low or intermediate risk patients as it provides 5 years disease free survival rate in 96% patients.
What other Drugs are given during the Treatment with Brachytherapy?
Since brachytherapy involves a minor surgical procedure, drugs are given to reduce the chances of complications like infection and to reduce pain.
- Antibiotics are given intravenously before the treatment. Most commonly used antibiotics are Ciprofloxacin and Cefazolin.
- Pain medications like paracetamol are given to relieve pain after the procedure.
What are the Possible Side Effects of Brachytherapy?
- Urinary problems like incontinence, frequent urination and feeling of burning while urinating. Urinary obstruction occurs in very rare cases.
- Erectile dysfunction
- Bowel problems like incontinence of stool and gas
- Pain and swelling near scrotum and anus
What Precautions need to be taken After the Treatment?
- Since the patient treated with permanent seed implantation brachytherapy carries radioactive material, they are advised to stay away from children and pregnant women for few weeks.
- It is advisable for men taking brachytherapy to wear condom while having sex.
- It is possible that the seed implants may migrate from their place. Therefore the patients are advised to strain their urine for first week after therapy so that any seed coming out can be caught.