Nov. 7, 2006 (Philadelphia) -- A newer method to deliver radiation to men with early prostate cancer appears to cause fewer serious side effects than the older radiation seed implant therapy, according to one of the first head-to-head comparisons of the two techniques.
In particular, men treated with the newer method, called intensity modulated radiation therapy, or IMRT, were less likely to need catheters to help them urinate, according to the study.
In the study, researchers at Fox Chase Cancer Center in Philadelphia compared results in 216 men treated with IMRT to 158 men treated with radiation seed implant therapy.
In IMRT, multiple radiation beams are focused at the prostate from many directions.
A computerized program allows doctors to adjust both the strength and the intensity of the beams, so that more radiation is blasted at the tumor and less at critical surrounding organs such as the bladder and rectum.
In radiation seed implant therapy, called brachytherapy, surgeons implant tiny radioactive seeds into the prostate gland. The seeds deliver high-dose radiation directly to the prostate for a predetermined length of time.
Among the findings, presented here at the annual meeting of the American Society for Therapeutic Radiology and Oncology:
- By four years later, 97% of the men who got IMRT were still cancer-free, as determined by negligible blood levels of prostate specific antigen (PSA), a protein produced by the prostate. In contrast, 86% of those implanted with radioactive seeds had negligible PSA levels. Rising PSA levels after treatment are thought to signal cancer recurrence.
- Only 1% of the men who got IMRT required insertion of a catheter to help them urinate because of bladder problems within the first three months after treatment. That compares with 7% in the seed group.
- After three months, 0.5% of men on IMRT, vs. 4% of those implanted with radioactive seeds, still required a catheter to help them urinate.
IMRT Safe Option
"Both IMRT and seed therapy offer excellent outcomes, with low toxicity," says researcher Thomas N. Eade, MBChB, a fellow in the department of radiation oncology at Fox Chase.
"IMRT offers a viable alternative to radioactive seeds, depending on personal preferences and disease characteristics," he tells WebMD.
In general, men with large prostates, poor urinary function, or those who have other pre-existing conditions such as diabetes are not good candidates for brachytherapy, Eade adds.
Najeeb Mohideen, MD, associate medical director in the department of radiation oncology at Northwest Community Healthcare in Arlington Heights, Ill., agrees both IMRT and seed implants are safe and effective options.
The next step, he says, is a trial comparing quality of life in men who receive the different treatments.
"Since both are effective and safe, side effects and quality of life are key factors when choosing a therapy," Mohideen tells WebMD.