Radiation & Brachytherapy for Prostate Cancer

This is a traditional radiation technique that treats the entire prostate. For those at high risk of the cancer spreading, the radiation therapist also delivers radiation to the pelvic lymph nodes.

Conformal External-Beam Therapy

This type of therapy creates 3D representations of the prostate, most often from a CT scan. The machine then designs a high radiation dose that conforms to the specific shape of the prostate.

Conformal therapy allows radiation therapists to safely use doses above traditional levels without significant increases in serious side effects or affecting nearby healthy tissue.

Intensity-Modulated Radiotherapy (IMRT)

Intensity-modulated radiotherapy (IMRT) is a refinement of conformal external-beam therapy. It uses a highly flexible beam to target the radiation with extreme precision according to the unique anatomy of each patient.

Besides permanent implants — which deliver low-dose-rate (LDR) radiotherapy — specialists use brachytherapy for prostate cancer using temporary, high-dose-rate (HDR) devices. Specialists typically use HDR devices for those with disease in an advanced stage that hasn’t yet spread.

In this technique, the radiation therapist delivers a high dose directly to the prostate over the course of an hour. You’ll receive several treatments on multiple days. Most people who receive radiation with an HDR device also have external-beam radiation for about five weeks.

If you have locally extensive prostate cancer (stages T3 to T6), your care team may suggest large fractions of radiotherapy using HDR interstitial techniques in combination with external-beam radiation treatment.

In some cases where the cancer is more advanced or showing signs of becoming aggressive, the prostate care team may recommend temporary androgen deprivation therapy (ADT) in combination with external beam radiation. ADT is a form of hormone therapy that blocks the body’s production of the male hormone testosterone. This causes prostate cancer to regress and become more sensitive to radiation therapy.

Brachytherapy (seed implants) as a stand-alone treatment is generally only used to treat early-stage prostate cancer. In this treatment, the prostate specialist implants between 30 and 60 radioactive seeds into the prostate gland. The implanted seeds remain in place permanently but become inert (no longer radioactvie) after a few months. 

This therapy allows the radiation therapist to deliver a high dose of radiation to the prostate with limited radiation exposure to surrounding tissues. In some cases this seeding technique is used in combination with external-beam radiation in order to optimize the radiation dose for more advanced stage prostate cancer. 

Stereotactic radiosurgery is a form of external beam radiation in which highly focused radiation beams are targeted to the prostate using a very precise image guidance system. BIDMC was the first hospital in the Boston area to use the CyberKnife to deliver this form of radiation. The CyberKnife uses a highly precise fiducial based tracking system to fine tune the position of the radiation beam treatment, thereby drastically reducing the number of radiation treatments. Given the long experince of CyberKnife at BIDMC we can comfortably say the results are equal to or better than those of traditional radiation therapy. 

After CyberKnife radiosurgery, very few (close to zero) men experience incontinence. In terms of sexual function, if a patient under age 65 had good erections prior to treatment, there is an 80% chance he will continue to do so after treatment. Of the 20% who experience erectile dysfunction, about 80% respond to an erectile dysfunction mediation like Viagra. The success rate for Viagra decreases under these conditions: 

• Being over age 65 
• Having diabetes, vascular disease and certain other conditions 
• Smoking 
• Taking beta blockers, anti-depressants and some other medications