External beam radiation therapy interferes with a cell’s ability to reproduce by damaging the DNA within the cell. Normal prostate cells can repair radiation damage much more effectively than prostate cancer cells. Thus, smaller hits of radiation over a period of time allow noncancerous tissue to repair itself after radiation. Most cancer cells cannot recover from radiation, even when it is given in small doses.
External beam radiation therapy is given via a highly complex piece of equipment called a linear accelerator. Treatments are given once a day, Monday through Friday for seven or eight weeks.
Dr. Gregory Echt and his team offer the most highly sophisticated methods of radiation therapy available in the United States, equal to that found in major medical center and academic settings, including:
Image-guided radiation therapy (IGRT) is recognized as the finest technology available in radiation oncology at this time. This technology allows the radiation beam to be altered depending upon day-to-day movement of the prostate gland. It is used in combination with intensity- modulated radiation therapy (IMRT) described below.
Intensity-modulated radiation therapy (IMRT) is a state-of-the-art technology that has raised the bar in radiation therapy nationwide. IMRT combines extremely precise tumor imaging techniques with equipment to deliver hundreds of thin beams of radiation to the exact tumor location in three-dimensional patterns from any angle.
Targeting radiation to the tumor allows delivery of the maximum dose of radiation needed to the cancer, while sparing healthy tissues. The precision afforded by IMRT allows doctors to deliver radiation to tumors that have been traditionally not possible to treat with radiation because of proximity to critical organs. Higher radiation doses are delivered safely and side effects from a course of radiation therapy are fewer. Results are precise control of radiation delivery, declining complication rates, and fewer side effects.
Research has indicated that higher doses of radiation cancer treatments result in higher rates of curing cancer:
How does a patient receive external beam radiation?
External beam radiation therapy generally involves treatments once a day, Monday through Friday for seven or eight weeks. The treatments are given while the patient lies on a table with the linear accelerator moving around the patient, distributing radiation. The treatments cause no pain and each session lasts just a few minutes. The primary target is the prostate gland itself. In addition, the seminal vesicles and lymph nodes(see description below) may be treated with radiation, since they are a relatively common site of cancer spread.
The seminal vesicles are glands at the base of the bladder and connected to the prostate gland that provide nutrients for the semen the fluid that is released through the penis during an orgasm. The lymph nodes are rounded masses of lymphatic tissue that store white blood cells. White blood cells help the body fight infection and other diseases.
Criteria necessary for a patient to be considered for external beam radiation:
- Good option for men opposed to or who cannot endure surgery or anesthesia for seed implant or HDR.
- Men with locally advanced stage prostate cancer, the type that has likely spread beyond the prostate gland but is confined to the pelvis, may find external beam radiation is the best option.
- Not easily tolerated by men with conditions of the rectum or colon such as inflammatory bowel disease.
Advantages of external beam radiation:
- Does not involve anesthesia or surgical recovery time
- No pain during treatment
- Only takes a few minutes each day
- Immediate side effects are mild and usually do not limit daily activities
- Risk of urinary incontinence is very low compared to surgery
- Often are fewer temporary urinary symptoms than with seed implantation
- With newer techniques, available at Dr. Echt’s radiation therapy centers, long-term side effects may be fewer. Higher-energy radiation beams can be more precisely focused with IMRT and IGRT technology. This advanced technology allows a radiation oncologist to tailor treatment to the anatomy of the individual patient.
Disadvantages of external beam radiation:
- Inconvenient for the patient because treatment is daily for five weeks or more. Patients in rural areas may find traditional seed implants or HDR implants much more convenient.
- From 30% to 40% of men treated with external beam radiation therapy become impotent, also called erectile dysfunction (ED). According to the American Cancer Society, impotence usually does not occur right after radiation therapy but gradually develops over a year or more. Radiation patients often respond to medication such as Viagra.
- Because the radiation beam passes through normal tissues such as the rectum, the bladder, and the intestines, on its way to the prostate, it damages some healthy cells. Radiation to the rectum and intestines may cause inflammation that results in some temporary discomfort during bowel movements and possibly diarrhea. These symptoms are successfully treated with over-the-counter medications and typically disappear over a few months.
- Radiation-induced fatigue may occur, but usually clears up when treatment is completed.
- Long-term studies have shown that outcomes are better for men who chose seed implantation therapy rather than external beam radiation. This is because the external beam radiation dose is lower and not as intense as that delivered with traditional seed implants or HDR therapy.
- External beam radiation can also cause short-term problems including proctitis (inflammation of the rectum) with occasional mild rectal bleeding that can be easily treated. Bowel problems such as diarrhea may occur and cystitis (inflammation of the bladder) may lead to irritation during urination. These symptoms typically disappear over a few months with over-the-counter medications.
Studies show that Seed Implants are more favorable controlling PSA and better than IMRT Therapy alone for prostate cancer treatment: