Comparative Study of Radiotherapy Treatments to Treat High Risk Prostate Cancer Patients

In North America, the number of new cases of prostate cancer increases every year. To this day, the standard curative treatment for high risk prostate cancer patients is external beam radiation therapy (EBRT) combined with hormonal manipulation (Luteinizing hormone-releasing hormone LHRH agonists such as Eligard) to lower levels of testosterone to slow down or even stop the growth of prostate cancer. It has been recently demonstrated that combination of high dose rate brachytherapy (HDRB) boost (direct insertion of radiation source in the prostate for killing the tumor) to EBRT could be an effective treatment for prostate cancer patients. On the other hand, other recent studies have suggested that dose escalation and hypofractionated radiation delivery (larger radiation dose per daily treatment) can be more efficient than standard fractionation in prostate cancer patients. This phase III clinical trial is designed to compare the safety of a conventional pelvic EBRT combined with a HDRB boost (i.e. 46 Gy in 23 fractions followed by a 15-Gy HDRB boost) to a shorter course of hypofractionated dose escalation radiotherapy (i.e. 68 Gy in 25 fractions) in patients with high risk prostate cancer. The patients will be randomized to either of the two different courses of treatment. All the patients will be also treated with hormonal therapy for a total duration of 28 months (2 months before radiation therapy (RT), 2 months during RT and for 24 months after RT). The patients will undergo different test before the treatment, such as bone scan, blood test, CT scan and bone density. The patient's follow-up will be the first month after start of RT, every 4 months for the first 2 years, then every 6 months the third year and then annually for 10 years. On every visit, the patient will undergo digital rectal examination (DRE) as well as evaluation of testosterone and prostate specific antigen (PSA) levels. The safety of the new course of radiation therapy will be evaluated by the acute (at and before 90 days) and delayed toxicities (at 90 days, at 180 days and after) measured by Common Terminology Criteria for Adverse Events (CTCAE version 4). We will also determine Biochemical Failure Free Survival, Distant Metastasis Free Survival, Disease Specific Survival, Overall Survival and the Health-related Quality of Life using the Expanded Prostate Cancer Index Composite (EPIC). We will also monitor the development of gastrointestinal and genitourinary toxicities and establish the predictive value of PTEN deletion and TMPRSS2ETS fusion (genetic markers to predict the nature and progression of prostate tumors). This study will be conducted through the Genitourinary Radiation Oncology Group of Quebec (GROUQ) in 12 selected radiation oncology centers. We plan to recruit 296 patients across Quebec and the recruitment should be completed within 24 months of activation.