December 2012, Vol 1, No 6
Stereotactic Body Radiation Therapy Is Effective, Cost Saving, and Convenient for Patients With Prostate CancerUncategorized
In the United States right now, intensity-modulated radiation therapy (IMRT) has largely replaced 3-D conformal radiation therapy as the technique of choice for most patients with organ-confined prostate cancer treated with radiation as primary therapy. Other techniques in use include brachytherapy, and at some centers proton beam therapy is being studied.
Of all the radiation technologies, it appears that stereotactic body radiation therapy (SBRT) delivered via the CyberKnife may be the most cost-effective and convenient for patients, while achieving at least equivalent efficacy in disease control, according to 2 retrospective studies reported at the 54th Annual Meeting of ASTRO. Both studies have a median follow-up of about 3 years, and larger studies with longer follow-up are needed to verify these findings.
SBRT delivers precise, high doses of radiation to the prostate using converging, finely collimated beams, targeting prostate tissue and sparing healthy tissue. The CyberKnife is a robotic technology used to deliver SBRT, and a course of prostate radiation typically takes 5 sessions (or 1-2.5 weeks) compared with 40 to 45 sessions using IMRT. SBRT technology is now available at about 150 centers in the United States.
A pooled analysis of 1100 patients with organ-confined prostate cancer treated at 8 different centers from 2003 to 2010 with CyberKnife SBRT showed that actuarial 5-year biochemical control was 95% for low-risk patients, 90% for intermediate-risk patients, and 80% for high-risk patients. Similar results were found in 150 patients treated with androgen deprivation therapy and with different dose levels of SBRT, reported Alan J. Katz, MD, Flushing Radiation Oncology, Flushing, NY.
“These results are 5% to 10% better than those with standard IMRT, which takes 40 to 45 days to deliver. At this point, the statistics should encourage men with organ-confined prostate cancer to seek SBRT as an alternative to IMRT, brachytherapy, or prostate surgery,” Katz stated.
SBRT can achieve huge cost savings, since Medicare reimbursement for SBRT is a median of $22,000 versus $40,000 to $45,000 for IMRT per patient. Also, because SBRT is delivered over 1 to 2.5 weeks instead of the 8 weeks needed for IMRT, there are cost savings in healthcare utilization and greater convenience for patients.
A second retrospective review, reported by Robert Meier, MD, Swedish Radiosurgery Center, Seattle, WA, focused on 129 patients with intermediate-risk, organ-confined prostate cancer treated with CyberKnife SBRT at 21 different institutions from December 2007 to April 2010. Median follow-up of these patients was 3 years (range, 2.5-4 years).
Quality-of-life (QOL) Expanded Prostate Cancer Index Composite scores showed that both urinary and bowel side effects were greater early in the course of treatment but by 6 months tended to approach baseline levels. At 2 years following SBRT, QOL scores were similar to baseline. Most urinary and bowel side effects were grades 1 and 2.
Biochemical control was achieved in 99.2% of patients; only 1 of 129 patients experienced a rise in prostate-specific antigen following a nadir achieved by SBRT.
Putting these preliminary results in context, Meier said that the typical rate of biochemical failure is 10% to 20% at 4 years with IMRT and proton beam therapy.
At a press conference, president-elect of ASTRO, Colleen Lawton, MD, Clinical Director of Radiation Oncology at the Medical College of Wisconsin, Milwaukee, said that these are exciting results, but longer follow-up is needed to establish SBRT as a standard of care.
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