Brachytherapy Versus Brachytherapy Plus Beam Radiation for Prostate Cancer: Morbidity Outcomes from Two Prospective Randomized Multicenter Trials
Presenter: M. Ghaly
Presenter's Affiliation: Department of Radiation Oncology, New York Methodist Hospital, Weill Medical Collage-Cornell University
Type of Session: Scientific
- 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.
- 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.
- 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.
- 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.
- 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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