What is radiation therapy (or radiotherapy)?

It involves the use of high-energy rays to damage or destroy tissue including cancer cells. Currently, radiotherapy used being used in a wide range of settings. These circumstances include primary treatment of localized prostate cancer, secondary treatment for cancer recurring within the region of the prostate, and for relief of pain and other symptoms related to prostate cancer that has spread to other parts of the body.

What are the different types of radiation therapy?

The different types of radiation treatment generally refer to the different ways radiation energy is being delivered to a particular area of the body or to a specific tumor site.

External Beam Radiation Therapy (EBRT): This is the most commonly used type of radiotherapy since the 1950s. The X-ray energy is generated by machines called linear accelerators, and then directed to a specific area of the body. All tissues within the path of the X-ray beam are affected including normal tissues and cancer cells. Three-dimensional (3-D) conformal technology has improved the ability to focus the damaging X-ray energy to the particular site of treatment, thereby reducing scattering to adjacent normal tissue. Just as with a plain X-ray test, there is a brief exposure to the radiation, typically lasting several minutes. Once the treatment is over, there is no radiation in the patient's body. EBRT is typically given once a day, five days a week. Primary treatment for localized prostate cancer usually requires about seven to eight weeks of treatment.

Brachytherapy: It is also referred to as "seed therapy" or a "prostate implant". This involves the insertion of radioactive material (seeds) into the body or into an organ/structure such as the prostate gland. Recent refinement of ultrasound techniques (transrectal ultrasound) has allowed more accurate placement of these seeds. There are currently two approaches to brachytherapy for localized prostate cancer: low-dose rate (LDR) and high-dose rate (HDR). Most centers are using the LDR technique in which the implanted radioactive seeds will emit (release) radiation over a period of months. The HDR technique involves temporary placement of a highly radioactive source into the prostate with treatment being given over a period of minutes and repeated two or three times over the course of several days. In some cases, brachytherapy may be combined with EBRT.

Radionuclide therapy: Radioactive substances may also be used for treatment of prostate cancer that has spread to the bones. These radioactive drugs or radionuclides are injected intravenously (IV) and are absorbed in the bones. These injections are typically given in the doctor's office, each has a lasting effect of a few months.

Who are appropriate candidates for radiation therapy?

For prostate cancer, radiation oncologists (physicians specializing in radiation therapy) rely on a combination of factors to categorize prostate cancer patients as "low risk", "intermediate risk", or "high risk" in terms of treatment failure. Some of these factors include finding on rectal and/or transrectal ultrasound examination of the prostate, PSA value, number of positive biopsy cores, and tumor grade. Similar to surgery, factors such as your age, overall health, urinary/bowel/sexual functions, and your own concerns about treatment need to be taken into account.

The "low risk" category will generally have the best chance of cure. The patients in this group have a normal rectal examination, a relatively lower PSA (usually less than 10 ng/ml), a limited number of positive biopsy cores, and lower grade tumor(s). These men tend to have good results with surgery, EBRT or brachytherapy.

Treatment of the "intermediate risk" group is not as straight forward. These patients may have palpable tumors on rectal examination or visible tumors by transrectal ultrasound, higher PSA levels (> 10 ng/ml), and higher tumor grade. Unfortunately the behavior of some of these tumors is often difficult to predict. Additional treatments such as combination of EBRT and brachytherapy, and hormonal therapy are commonly prescribed for these men who are choosing to have some form of radiation therapy. Currently, there are opportunities for these men to enter clinical trials seeking to improve the treatment of these difficult cancers.

The "high risk" clinically localized prostate cancer group has not done well with radiation or surgery alone. Most of these men have obvious abnormality of rectal examination, high PSA (>20 ng/ml), and high grade tumors. Although spread of disease to other parts of the body ( lymph nodes and bones) may not be evident due to the limitations of CT scan and bone scan technology, the likelihood of microscopic disease is high. Currently, the initial treatment of these cancers involves hormonal therapy along with EBRT, but the long-term outcome remains poor. Current clinical trials include the use of hormonal therapy, chemotherapy, radiation therapy and surgery in combinations (multi-modality approach).

What are some of the side effects of radiation therapy?

The principle side effects of radiation treatment are related to the treated area. Common side effects during the time of treatment include urinary frequency, urinary urgency, mild burning with urination, and bowel irritability including diarrhea, gas, bowel urgency and pain. Most of these symptoms do resolve a few months after completing treatment. Delayed side effects can occur years after treatment including urethral strictures, bleeding from the bladder, prostate and rectum, and rarely other cancers (bladder, colon). The risk of urinary incontinence is significantly increased when patients develop urethral strictures that require surgery to relieve. The incidence of erectile dysfunction or impotence generally increases over time as the harmful effects of radiation on the blood supply to the penis and the nerves controlling erections gradually develop.

Is radiation therapy useful following prostate cancer surgery (radical prostatectomy)?

In a small well-selected group of surgical patients, radiation therapy following initial surgery may be helpful. Patients with positive surgical margins (microscopic tumor cells seen at margins of resection) have been considered for radiotherapy to the prostate region in the pelvis. However, studies which followed patients with positive surgical margins show that only a minority of these patients will ever show recurrent disease. Most of these patients have larger tumors which are often high-grade. Unfortunately, this same group of patients is at higher risk of having microscopic spread of the cancer to areas outside of the typical radiation field of the prostate area in the pelvis. The rare patients with late recurrence to the pelvic area may also benefit from radiation therapy.

Are patients eligible for surgery after failed radiation therapy?

Yes, but the risk of complications is higher, including the risk of incontinence, impotence, and rectal injury.

How successful is radiation therapy in the treatment of metastatic cancer?

EBRT is helpful in decreasing or relieving pain related to prostate cancer that has spread to the bones. However, it is not curative.

Frequently asked questions:

Will radiation therapy affect my sexual function?

Yes, possibly. The risk of impotence following radiation can vary widely. The addition of hormonal therapy will certainly affect function. Bothersome (sometimes painful) bladder and rectal symptoms as a result of radiation can affect your general well-being and eventually affect your sexual activity.

Since the cancerous tumor is not removed with radiation treatment, how will I know if it's gone?

Follow-up after radiation therapy relies on PSA testing and rectal examination. Unlike surgery, the PSA level typically takes about 2 years to reach its lowest level after radiation treatment. If there is a rise in the PSA level, a biopsy procedure may be required.

Glossary Terms

chemotherapy - medications used to treat cancer that has spread to other parts of the body;
clinical - pertaining to the status of a disease based on the findings on physical examination, and imaging tests (such as CT scan and bone scan);
erectile dysfunction - the inability to get or maintain an erection for satisfactory sexual intercourse. Also known as impotence;
hormonal therapy - for prostate cancer, it involves using medications to stop testosterone production;
intravenous - also referred to as IV; existing or occurring inside a vein (medication given through a vein);
metastasized - spread of cancer from its origin to other parts of the body;
oncologist - a doctor who specializes in the treatment of cancer;
prostatectomy - surgical procedure for the removal of the prostate; radical means complete removal;
tumor - an abnormal mass of tissue or growth of cells;
urethral stricture - a narrowing or blockage of the urine channel leading from the bladder to the outside;

*  This information is not intended to substitute for a consultation with a urologist. It is offered to educate patients on the basis of urological conditions in order to get the most out of their office visits and consultations. Please see our web page disclaimer for addition information.

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