Stereotactic Body Radiation Therapy Cost-Saving, Convenient for Patients with Prostate Cancer

November 2012, Vol 3, No 8

Boston, MA—In the United States right now, intensity modulated radiation therapy (IMRT) has largely replaced 3-dimensional conformal radiation therapy as the technique of choice for most patients with organ-confined prostate cancer that is being treated with radiation as the primary therapy.

Another technique in use is brachytherapy, and, at some centers, proton beam therapy is being studied.

Of all of these radiation technologies, stereotactic body radiation therapy (SBRT) delivered via the Cyber­Knife is potentially 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 2012 American Society for Radiation Oncology annual meeting. Both studies have a median follow-up of approximately 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 that target prostate tissue and spare normal tissue. The CyberKnife is a robotic technology used to deliver SBRT. 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 approximately 150 centers in the United States.

Pooled Analysis of Organ-Confined Prostate Cancer

A pooled analysis of 1100 patients with organ-confined prostate cancer who were treated at 8 different centers between 2003 and 2010 with Cyber­knife SBRT showed that the 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 who were treated with androgen deprivation therapy and with different doses of SBRT, reported Alan J. Katz, MD, JD, a radiation oncologist at Flushing Radiation Oncology, 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,” Dr Katz stated.

Significant Cost-Savings

SBRT can achieve huge cost-savings, because Medicare reimbursement for SBRT is a median of $22,000 versus $40,000 to $45,000 per patient for IMRT.

In addition, because SBRT is delivered over 1 to 2.5 weeks instead of the 8 weeks needed for IMRT, the cost-savings in healthcare utilization are significant, and the shorter duration offers greater convenience for patients.

Intermediate-Risk Prostate Cancer

A second retrospective review, which was reported by Robert M. Meier, MD, a radiation oncologist at Swedish Radiosurgery Center, Seattle, WA, focused on 129 patients with intermediate-risk, organ-confined pros­tate cancer who were treated with CyberKnife SBRT at 21 different institutions between December 2007 and April 2010. The median follow-up was 3 years (range, 2.5-4 years).

The quality-of-life 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 after SBRT, quality-of-life 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 after a nadir achieved by SBRT.

Putting these preliminary results in context, Dr 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, the 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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