In a nutshell
This phase 2 trial aims to compare conventional radiation therapy with a very focused type of radiation therapy for intermediate- and high-risk prostate cancer. The main outcome to be investigated is the number of side effects and the rate of disease recurrence at 5 years. The trial is recruiting in British Columbia, Canada.
Radiation therapy is a first-line treatment for prostate cancer. It can be combined with hormone therapy for a more intensive intervention, such as for prostate cancer that is at high-risk of progression.
External beam radiation therapy (EBRT) involves directing high-energy rays from outside the body at the tumor site to kill cancer cells. Brachytherapy is a type of radiation therapy where the radiation source is placed inside the prostate. While both brachytherapy and EBRT are associated with good treatment effectiveness, they both have limitations. EBRT often takes many weeks to deliver. Brachytherapy produces excellent treatment outcomes but is invasive and not all patients are eligible to receive it.
Stereotactic ablative radiotherapy (SABR) is a type of EBRT that uses focused radiation beams to deliver high radiation dose with high accuracy (stereotactically). Treatments are short, non-invasive, applicable to patients not able to do brachytherapy, and may be more effective than conventional EBRT.
This study will compare SABR with EBRT when combined with hormone therapy in men with intermediate- or high-risk prostate cancer. The number of side effects will be recorded for each treatment, as well as the rate of patients experiencing disease recurrence and quality of life measures.
Who are they looking for?
This study will recruit about 80 men with intermediate- or high-risk localized (confined) prostate cancer. Testosterone and PSA (prostate specific antigens; a protein elevated in the blood in prostate cancer) levels in the blood must be measured not more than 60 days before participation. A physical examination with a digital rectal examination must be carried out within 60 days of participation of commencement of hormone therapy. For high-risk patients, CT scans (a body imaging test) must confirm that the cancer has not spread outside the prostate no more than 60 days before participation. CT scans are optional for patients with intermediate-risk disease. Hormone therapy may be started before study participation. Participants should have a life expectancy of at least 5 years.
Patients cannot take part in the trial if the cancer has spread outside of the prostate gland. The size of the prostate must be more than 90 cubic centimeters in order to take part. A history of inflammatory bowel disease, previous pelvic radiation, a hip prosthesis, or any other cancers that were active within the last 5 years (with the exception of treated skin cancer) will prevent patients from taking part.
How will it work
Participants will be randomly assigned to either undergo SABR or EBRT in combination with hormone therapy. Patients treated with conventional EBRT will receive 73.68 Gy in 28 fractions (5 treatment days per week over 5.5 weeks). Patients treated with SABR will receive a prescribed dose of 36.25 Gy in 5 fractions over 5 weeks (one treatment day per week).
Hormone therapy will be administered to both groups as goserelin acetate (Zoladex), but other GNRH agonists are also permitted. The total duration of hormone therapy will be 6 months for men with intermediate-risk disease, and 18 months for those with high-risk disease. Hormone therapy is to be initiated prior to the start of radiation therapy.
The number of acute and late side effects will be recorded for each treatment over a 5-year period. The rate of patients experiencing disease recurrence (based on blood tests) will also be measured over the same period, Questionnaires will assess changes in quality of life.
Clinical trial locations
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