Brachytherapy Versus Brachytherapy Plus Beam Radiation for Prostate Cancer: Morbidity Outcomes from Two Prospective Randomized Multicenter Trials

Reviewer: William Levin, MD
OncoLink
Last Modified: October 7, 2002

Presenter: M. Ghaly
Presenter's Affiliation: Department of Radiation Oncology, New York Methodist Hospital, Weill Medical Collage-Cornell University
Type of Session: Scientific

Background

Localized prostate cancer is typically treated with surgery or radiation therapy.
Forms of radiation therapy include external beam, brachytherapy(implantation of radioactive seeds) or a combination of the two.
To date, most radiation side-effect data are based on external beam therapy.
Common side-effects involve the bowel or bladder, as well as sexual dysfunction.
The current study was designed to explore the radiation side-effect profile of brachytherapy, given alone and in conjunction with external beam.

Materials and Methods

Data was taken from 220 patients previously enrolled on 2 separate randomized trials.
In the first study, patients were randomized to implantation with I-125 versus implantation with Pd-103.
In a second trial, 111 intermediate-risk patients received Pd-103 implantation and then were randomized to receive either 20Gy or 44Gy of external beam radiation.
Side-effect data was obtained by way of mail-in questionaire. American Urologic Association (AUA)and RTOG inventories were used.
Use of alpha blockers was not controlled for.
Minimum follow-up was one year.

Results

For the entire group, urinary symptoms peaked at one month.
Patients with Pd-103 implants had more symptoms (AUA score of 17) than those who received I-125 (AUA score of 14) (P=0.02)
The addition of external beam therapy did not increase symptoms (AUA score of 14)
Post-implant AUA scores declined more rapidly in patients treated with the Pd-103 implants +/- external beam, versus those that had I-125 +/- external beam.
On average, the symptoms of patients treated with Pd-103 subsided by 6 months. In contrast, those patients treated with I-125 still had a significant elevation in their symptom score at 12 months.
Grade 1 rectal morbity was greatest in patients receiving Pd-103 alone, occuring in 30% of these patients by one month.
Of all the patients that did get grade 1 or 2 rectal toxicity (no patient had grade 3 toxicity) on average, those with Pd-103 implants saw quicker resolution of their symptoms, versus those with the I-125 implants.

Author's Conclusions

The incidence and time course of urinary and rectal toxicity following prostate brachytherapy is dependent on isotope choice, and by the use of supplemental external beam radiation.

Clinical/Scientific Implications

From this study, it appears that grade 1 and 2 rectal complications (which are quite common in radiation therapy) are more common in patients treated with Pd-103. However, symptoms resolved faster in these patients, versus those who received I-125 implant.
Likewise, urinary symptoms resolved quicker in the Pd-103 group.
It is not entirely clear why morbidity did not increase with the addition of external beam therapy to brachytherapy. We must remember that this study is the combination of 2 separate studies and, therefore, statistical and technical factors may complicate interpretation.
It is hard to make full conclusions regarding late effects of treatment given the short follow-up, particularly in regard to sexual dysfunction.

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