Addition of External Beam Radiation Therapy to Low-dose Rate Brachytherapy

Addition of External Beam Radiation Therapy to Low-dose Rate Brachytherapy May Improve Prostate Cancer Outcomes.

Among men receiving radiation therapy for prostate cancer, the addition of external beam radiation therapy to low-dose rate brachytherapy reduced the likelihood of rise in serum prostate-specific antigen (PSA) levels after treatment compared to use of low-dose rate brachytherapy alone. These results were published in the journal Urology.

Prostate cancer is second only to non–melanoma skin cancers as the most commonly diagnosed cancer in men in the U.S. The prostate is a walnut-sized gland that is located between the bladder and rectum. It is responsible for forming a component of semen.

Early prostate cancer refers to cancer that has not spread outside of the prostate. Radiation therapy is a commonly used treatment for early prostate cancer. External beam radiation therapy (EBRT) is a type of radiation that is delivered by a machine outside the body. It often requires multiple trips to a radiation facility to complete several courses of radiation therapy.

Brachytherapy, or interstitial radiation therapy, is a type of radiation therapy that involves the implantation of small “seeds” that spontaneously emit radiation for a specific period of time. The seeds are surgically implanted into and sometimes surrounding the site of cancer; the seeds continuously emit cancer-killing radiation to cancer cells. Low-dose rate brachytherapy refers to brachytherapy in which the radiation is delivered slowly over an extended period

To assess whether the addition of EBRT to low-dose rate brachytherapy produced better patient outcomes than use of low-dose rate brachytherapy alone, researchers evaluated 189 prostate cancer patients.

Seventy-one percent of patients received low-dose rate brachytherapy alone, and 29% received EBRT in addition to low-dose rate brachytherapy. Most patients had cancer confined to the prostate (T1 or T2), but three patients had cancer that extended through the prostate capsule (T3). All the patients with T3 cancer received EBRT in addition to low-dose rate brachytherapy. Patients with high Gleason scores were also more likely to receive EBRT in addition to low-dose rate brachytherapy.

The researchers assessed whether the addition of EBRT reduced the likelihood that a patient would experience post-treatment increases in PSA levels (these increases are referred to as “biochemical failures”).

  • Patients treated with the combination of EBRT and low-dose rate brachytherapy were less likely to experience a post-treatment PSA increase than patients treated with low-dose rate brachytherapy alone. After five years, the probability of surviving without a PSA increase was 80% among men treated with EBRT and low-dose rate brachytherapy, and 59% among men treated with low-dose rate brachytherapy alone.

The researchers conclude that in this study, the addition of EBRT to low-dose rate brachytherapy reduced the likelihood of a post-treatment PSA increase. The researchers note that additional research is necessary to determine which subgroups of prostate cancer patients are most likely to benefit from the addition of EBRT to low-dose rate brachytherapy.

Reference: Jani AB, Feinstein JM, Pasciak R Krengel S, Weichselbaum RR. Role of External Beam Radiotherapy with Low-dose-rate Brachytherapy in Treatment of Prostate Cancer. Urology. 2006;67:1007-1011.

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