High-dose conformal radiation therapy results in better long-term cancer control than conventional-dose radiation therapy for treatment of localized prostate cancer, according to the results of a study published in the Journal of Clinical Oncology.1
Early-stage prostate cancer refers to Stage I or II prostate cancer that is limited to the prostate and nearby lymph nodes and has not spread from the prostate to distant sites in the body. Over 90% of patients with low-risk prostate cancer (Stage I, PSA less than 10 ng/mL, Gleason score lower than six) treated with radiation therapy will survive five years after treatment, and most patients who die do so of causes other than prostate cancer. However, 40-65% of patients with Gleason scores higher than six and high PSA levels will experience disease recurrence within five years of radiation treatment.
Because of the relatively poor outcomes for patients with adverse risk factors, researchers continue to evaluate more intensive treatments for this group of patients. A higher radiation dose to the prostate appears to improve outcomes.
Researchers compared conventional radiation therapy to high-dose conformal radiation therapy in 393 patients with early-stage prostate cancer and a PSA of less than 15 ng/mL. Patients were randomly assigned to receive either conventional-dose or high-dose radiation. At a median follow-up of 8.9 years, the researchers have concluded the following:
- Men receiving high-dose radiation were 43% less likely to have a local recurrence.
- The biochemical failure rate (PSA higher than 1 ng/mL) was 16.7% for the high-dose group compared with 32.4% for the conventional-dose group.
- Patients with low-risk disease had biochemical failure rates of 7.1% in the high-dose group compared with 28.2% in the conventional-dose group.
- Patients with intermediate-risk disease had biochemical failure rates of 30.4% in the high-dose group compared with 42.1% in the conventional-dose group.
- Overall survival in the high-dose group was 83.4% compared with 78.4% in the conventional-dose group.
There were no differences between the two groups in the rate of urinary and gastrointestinal complications. The researchers concluded that high-dose radiation therapy produces superior long-term cancer control of localized prostate cancer when compared with conventional-dose radiation therapy.
1 Zietman AL, Bae K, Slater J, et al. Randomized trial comparing conventional-dose with high-dose conformal radiation therapy in early-stage adenocarcinoma of the prostate: Long-term results from Proton Radiation Oncology Group/American College of Radiology 95-09. Journal of Clinical Oncology. 2010; 28: 1106-1111.
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