The two types of radiation therapy are:
- Brachytherapy – The permanent implantation of radioactive "seeds" (small pellets of a radioactive isotope) directly into the prostate. These seeds emit a gradually diminishing dose of radiation to the surrounding tissue, killing the cancer cells. After about a month, the emission has declined to negligible amounts. Brachytherapy is more often an option for small size prostate glands and earlier stage prostate cancers
- External beam radiation – The exposure of cancerous cells to x-rays from external sources. In this treatment, the patient is treated with short exposures to high-energy x-rays each day over a period of several weeks. Our state-of-the-art linear accelerators precisely control radiation beams so that only the tumor site receives the full radiation, significantly reducing the exposure of normal cells.
Brachytherapy is the implantation of 40-150 small pellets of a radioactive substance into the prostate. This procedure is done in a single day under general anesthesia, takes about three hours to complete, and does not require an overnight stay in the hospital.
During the procedure the seeds are implanted uniformly throughout the prostate. The seeds are made up of palladium and release small amounts of radioactivity into the surrounding prostate that destroy cancer cells. The seeds are permanently placed, and like all radioactive material, emissions decline over time and after a few weeks they are no longer active. Some precautions should be taken to limit prolonged close contact (closer than three feet) with children or pregnant women for the first month after implantation, but after that no precautions are needed.
About a month after implantation, patients return for a CT scan that allows the seed and dosage distribution to be documented. About three months after that, the patient returns again for a follow-up exam that includes a PSA.
Side effects of brachytherapy may include difficulty urinating, urinary urgency or burning, and perhaps loose stools. Side effects generally decline after a month.
External beam radiation
This treatment is much like getting a regular x-ray. Each treatment lasts only a few minutes. Men usually have 5 treatments per week in an outpatient treatment center over a period of about nine weeks. The treatment itself is painless.
The process begins about three weeks before the first radiation treatment session with the implantation of two gold coils into the prostate. These coils allow the precise calibration of the radiation beams during the subsequent treatment sessions. The procedure takes about 30 minutes and is performed under local anesthesia. Patients only need someone to drive them home if they receive additional sedation.
Two weeks before the treatment sessions begin, the patient comes to the hospital for a one hour planning session in which he has an MRI, and the treatment schedule is finalized.
When the treatment sessions begin, the patient comes to the hospital every weekday for about nine weeks. Each day includes a 30 minute visit during which the patient receives a radiation treatment. Once a week patients meet with their doctor and other team members to report on progress and any side effects.
Norris Cotton Cancer Center treats patients with prostate cancer with advanced linear accelerators from Varian Medical Systems. These combine specialized medical imaging with precise and powerful radiation delivery to enable advanced new therapies that shorten treatment times, reduce side effects, and offer new hope for patients previously considered to be untreatable.
Side effects of radiation therapy include short-term irritative of the bladder or bowels, with symptoms generally resolving within two weeks or so after completion of the treatments. Long-term complications resulting from prostate radiation therapy are generally rare (under 5%), except for long-term risk of erectile dysfunction (ED), which may arise in upwards of 30-40% of treated patients. ED risk varies greatly based on patient age and pre-existing function.
After completion of the treatment sessions, there is a series of follow-up visits starting one month after therapy ends and continuing every three-six months into the future.
Many patients will be considered for "hormone therapy" along with their external beam radiation therapy. This is sometimes called "androgen deprivation therapy" (ADT) and includes an intramuscular shot plus or minus an oral pill to decrease a patient's testosterone level. The duration of this treatment can be from four months through two years starting just before and continuing after the radiation therapy. Clinical trials have shown that ADT improves the survival of patients with intermediate or high risk prostate cancer undergoing external beam radiation therapy. Side effects of ADT may include fatigue, hot flashes, decreased libido or ED, mood changes, bone loss and cardiovascular risk, though the latter are generally present with longer term therapy. Pros and cons of ADT are reviewed in detail when patients meet with radiation oncology in considering their treatment options.