A large comparative effectiveness study presented at the fourth annual Genitourinary Cancers Symposium, being held February 2-4, 2012, at the San Francisco Marriott Marquis in San Francisco, Ca, USA, shows that men with localized prostate cancer who are treated with Intensity Modulated Radiation Therapy or IMRT are less likely to experience cancer recurrences or significant side effects from treatment than those who receive conventional conformal radiation therapy (CRT).

The analysis also found that a more costly form of radiation treatment, called proton beam therapy, did not significantly improve outcomes compared to IMRT. This study is the first to comprehensively examine the comparative outcomes of patients with prostate cancer treated with these three types of radiation therapy.

?Patients and doctors are often drawn to new treatments, but there have not been many studies that directly compare new radiation therapy options to older ones,? said senior author Ronald Chen, MD, MPH, assistant professor of radiation oncology at the University of North Carolina (UNC) at Chapel Hill and Research Fellow at the Sheps Center for Health Services Research at UNC.

A change in practice
?In the past 10 years, IMRT has largely replaced conventional conformal radiation therapy as the main radiation technique for prostate cancer, without much data to support it. This study validated our change in practice, showing that IMRT better controls prostate cancer and results in fewer side effects.?

Adopting new theapies
Comparative effectiveness research is designed to help clinicians and patients make more informed treatment decisions and may also influence the future adoption of new therapies and technologies in medicine overall.

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Shaping the radiation field
IMRT is a more advanced form of radiation that enables doctors to shape and vary the intensity of the radiation field, delivering an increased radiation dose to the tumor and sparing more nearby normal tissue than is possible with conventional conformal radiation therapy. In proton beam therapy, cancerous tumors are irradiated with high-energy particles called protons. The clinical effect of using protons compared to X-rays (which are used with CRT and IMRT) for prostate cancer is not completely understood, though proton beam radiation is often thought to be able to further spare normal tissue compared to X-rays.

Radiation-related side effects
In the study, Chen and his team analyzed data from the Surveillance, Epidemiology, and End Results (SEER)-Medicare database of more than 12,000 patients with localized prostate cancer who were treated with conventional conformal radiation therapy, IMRT, or proton beam radiation from 2002 to 2007. They examined the proportion of patients who were diagnosed with radiation-related side effects after treatment, including gastrointestinal and urinary problems, erectile dysfunction and hip fractures. They also determined the proportion of patients in each group who required additional cancer treatments after radiation, using this as an indication of cancer recurrence.

Better cancer control; reducing recurrence
The researchers found that after adjusting for demographic, disease and institutional characteristics, patients who received IMRT had fewer gastrointestinal problems diagnosed (rate ratio 0.91, meaning that IMRT reduced gastrointestinal problems by 9%) and fewer hip fractures (rate ratio 0.78, or a reduction of 22%) than those who received conventional conformal radiation therapy, suggesting that IMRT is a safer radiation technique. They also found that IMRT patients were less likely to require additional cancer treatments (rate ratio 0.81, or 19% fewer additional cancer treatments), suggesting that IMRT may offer better cancer control and reduce recurrence.

Higher dose of radiation
?Several trials have shown that higher doses of radiation therapy improve disease control, and it is likely that IMRT allowed a higher dose of radiation to be given to the prostate than conventional conformal radiation,resulting in improved cure rates while simultaneously reducing side effects due to less radiation being given to organs surrounding the prostate,? Chen said.

The investigators also found that patients who received proton therapy had a higher rate of gastrointestinal problems, and did not have significantly improved outcomes compared to IMRT. ?We?ve seen a rapid growth in the number of proton facilities in the U.S. in the past five years, despite its very high costs. Yet with the data we have to date in the published literature, there does not appear to be a clear benefit of proton bean therapy compared to IMRT,? said Chen. ?The technology needs to be closely examined through comparative effectiveness research before we adopt it as the ?next? treatment for prostate cancer.?

For more information:
Sheets NC, Goldin G, Meyer AM, Wu Y, Chang Y, Sturmer T, Holmes JA, Reeve BB, Godley PA, Carpenter WR, Chen RC. Comparative effectiveness of intensity modulated radiation therapy (IMRT), proton therapy (PT), and conformal radiation therapy (CRT) in the treatment of localized prostate cancer. Abstract #3. Fourth annual Genitourinary Cancers Symposium (2012)

What: Oral Abstract Session A
Senior Author: Ronald Chen, MD (University of North Carolina, Chapel Hill, NC)
When: Thursday, February 2, 2012 1:15 PM – 03:05 PM PT.

Also read:
Patients Receiving Radiation with IMRT for Head and Neck Cancer Report Better Quality of Life Post-treatment.

Foto credit: 2012 Genitourinary Cancers Symposium – General views at the 2012 Genitourinary Cancers Symposium (GI) meeting at the Marriott Marquis, Thursday February 2, 2012. A record 2500 attendees from around the world were on hand to learn the latest treatment and research in Genitourinary cancers from fellow physicians, researchers, health care professionals, cancer survivors and patient advocates. Photo by ? ASCO/Todd Buchanan 2012

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