Comparison of Biochemical and Toxicity Outcomes from a Contemporaneous Cohort Study of Low-Risk Prostate Cancer Treated with Different Radiation Techniques
Presenting Author: Perekaa Sethukavalan MD
Presenting Author Affiliation: Sunnybrook Health Sciences Centre, Odette Cancer Centre, Toronto, ON, Canada
Prostate cancer is the most common malignancy of adult men, and many potentially effective treatment options exist. These include active surveillance, surgery or radiation therapy, and radiation therapy can be delivered in many different ways – including external beam radiation therapy (EBRT) or brachytherapy, when radioactive seeds or other sources are placed in the patient. Stereotactic body radiotherapy (SBRT) is an emerging and popular radiotherapy technique. It involves using high doses of radiation delivered over a shorter time frame than conventional external beam radiation, and appears to be effective, well tolerated, cost effective and convenient. However, the outcomes for patients treated with SBRT are less known compared to more conventional radiation options for patients with prostate cancer. In particular, researchers have been concerned that SBRT might be associated with risk of increased late toxicity.
The authors of this study sought to evaluate and compare late toxicities and biochemical disease-free survival (bDFS) of low risk prostate cancer patients treated with SBRT (35Gy delivered in 5 fractions), standard 3D conformal EBRT (76Gy delivered in 38 fractions) or low-dose brachytherapy. They analyzed a group of 357 patients treated at the Odette Cancer Center from 2002 – 2008. Of these, 84 were treated with SBRT, 81 standard EBRT, and 192 with brachytherapy. They followed the patients for a median of about 5 years. ;At 5 years follow up there was no difference in biochemical disease free survival between the 3 cohorts of patients, with about 97% of patients in each group being free of prostate cancer. Overall, all treatments were very well tolerated and the risks of side effects were similar between the two groups. The only difference was that patients who had brachytherapy were somewhat more likely to have hematuria (blood in the urine) months or years after treatment. The authors concluded that all three modalities were equally effective at treating low risk prostate cancer, and all were very well tolerated. They note that SBRT and brachytherapy are more convenient and less costly than standard fractionation EBRT.
This was an important and well-performed study assessing the toxicity and effectiveness of multiple radiation treatment modalities commonly utilized for the treatment of low risk prostate cancer.
Patients with low risk prostate cancer have numerous treatment options and it is vitally important to better define the toxicity risks of each modality in order to allow patients to make the most informed decisions possible. As SBRT appears favorable in terms of healthcare cost and patient convenience, we must continue to follow patients for late toxicities that may not yet be apparent, as some side effects may develop later than 5 years into survivorship from prostate cancer.