Hypofractionated 3D-Conformal RT
Wednesday, November 04 2009 20:41
Shorter Radiation Course Stops Cancer Growth in High-risk Prostate Cancer Patients
Hypofractionated radiation treatment, a newer type of radiation treatment that delivers higher doses of radiation in fewer treatments than conventional radiation therapy, is significantly more effective than the older method in stopping cancer growth in high risk patients and causes no increase in negative side effects, an Italian clinical trial shows.
"The study not only shows that hypofractionated radiation improves the control of prostate cancer, but it also cuts the number of treatment visits in half for patients. This is an important benefit for these high-risk patients, who are typically an older, less mobile population," Giorgio Arcangeli, M.D., lead author of the study and a radiation oncologist at the Regina Elena National Cancer Institute in Rome, Italy said. "It’s also especially helpful for those living at long distance from radiation treatment centers."
Dr. Arcangeli presented the trial findings November 4, 2009 in Chicago at the 51st Annual Meeting of the American Society for Radiation Oncology (ASTRO).
All men in the study were treated with three-dimensional conformal radiation therapy, or 3D-CRT. It is a type of external beam radiation therapy that uses computers and special imaging techniques to show the size, shape and location of the tumor as well as surrounding organs to precisely tailor the radiation beams to the size and shape of the tumor. Because the radiation beams are very precisely directed, nearby normal tissue receives less radiation and is able to heal more quickly.
During external beam radiation therapy, a beam of radiation is directed through the skin to the cancer and the immediate surrounding area in order to destroy the main tumor and any nearby cancer cells.
From January 2003 to December 2007, a total of 168 high risk prostate cancer patients were randomized to receive either hypofractionated or conventional schedules of 3D-CRT to the prostate and surrounding area. Patients who received hypofractionated radiation had only 20 sessions of radiation (four weeks of daily radiation therapy treatments), instead of the 40 to 45 (eight to nine weeks of daily treatments) sessions typically required during standard radiation treatment.
Study findings show that the patients treated with hypofractionated radiation had a better chance (87 percent vs. 79 percent) that their cancer would stop growing, compared to patients treated with standard radiation therapy.
There was also no difference in the late side effects of genito-urinary and gastro-intestinal function between the two groups of patients, Dr. Arcangelli says.
Effect of hyperfractionated radiation on the rectal wall was investigated earlier in a Phase 2 trial (see links below). For 6 months that study followed 114 patients radiated for localized prostate cancer and concluded that "The similar rate of late toxicity in the two arms seems to indicate the feasibility of hypofractionated regimes in prostate cancer." There was a difference of under 3% in the number of cases of rectal wall side effects reported by these patients and confirmed by the physicians.
"Studies are in progress to test the benefits of even shorter treatment schedules," Dr. Arcangeli said.
Sources & Links to Related Material
A summary of the trial, "A Phase III Randomized Study Of High Dose Conventional Vs Hypofractionated Radiotherapy In Patients With High Risk Prostate Cancer," was presented on Wednesday, November 4, 2009.
For more information on radiation therapy for prostate cancer, visit www.rtanswers.org.
EBRT is a mailing list offering discussion and support for patients interested in external beam radiotherapy. The list has extensive archives available for members to browse. Visit our page for patient-centered prostate cancer related mailing lists.
Dr. Giorgio Arcangeli and colleagues recently published results from a Phase 2 trial comparing rectal side effects from hyperfracationated and standard EBR. This report is available in full free text online:
J Exp Clin Cancer Res. 2009; 28 (1)117. Published online 2009 August 19
". . .In this work, a modeling of late rectal toxicity in patients with localized prostate cancer was performed. The patients were randomly assigned to receive 80 Gy in 40 fractions over 8 weeks (arm A) or 62 Gy in 20 fractions over 5 weeks to the prostate (arm B). The comparison between the conventional and the hypofractionated arms allowed to evaluate the response of rectal toxicity to changes in fractionation.
The crude rate of ? G2 late rectal toxicity were 14.0% and 12.3% for arm A and B respectively, thus very close to the actuarial values at 30 months . . . indicating that this time can be considered adequate to report the late rectal toxicity, as documented also by other studies . . . . The comparable toxicity rates observed in the two arms suggest that the hypofractionated regimes in prostate cancer are feasible, as previously reported in other studies . . . . The similar rate of late toxicity in the two arms seems to indicate the feasibility of hypofractionated regimes in prostate cancer.
Reported November 4, 2009 by Jacqueline Strax.
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