In the April 18 issue of JAMA, a study comparing traditional radiation therapy to treat localized prostate cancer with intensity-modulated radiation therapy (IMRT) and proton therapy reveals thats IMRT was linked to fewer gastrointestinal side effects, receipt of additional cancer treatments and hip fractures but to more erectile dysfunction, whilst those who received proton therapy reported more gastrointestinal side effects.

Results of the study were presented at a JAMA media briefing at the National Press Club by Ronald C. Chen, M.D., M.P.H., of the University of North Carolina at Chapel Hill.
br> The researchers write:

“Prostate cancer is the most common malignancy in men, with more than 200,000 diagnoses and 30,000 deaths per year. Recent advances in technology have led to costlier treatments such as minimally invasive radical prostatectomy, intensity-modulated radiation therapy, and proton therapy.

The adoption of these technologies resulted in a $350 million increase in health care expenditures in 2005 alone.

The clinical benefit from these newer treatments in unproven, and comparative effectiveness research examining different radiation techniques is lacking.”

In order to examine the side effects of different radiation techniques and disease control outcomes for individuals with prostate cancer, Dr. Chen, and his team conducted a study using Surveillance, Epidemiology, and End Results-Medicare-linked data from 2000 through 2009 for patients with localized prostate cancer.

The team compared conformal radiation therapy with IMRT (currently the most commonly used technique), and proton therapy with IMRT.

The primary outcomes measured in the study were:

  • Rates of gastrointestinal side effects, such as diarrhea or rectal bleeding

  • Hip fractures

  • Erectile dysfunction

  • Receipt of additional cancer therapy – as an indicator for disease recurrence

In the propensity-score adjusted analysis (n = 12,976), the researchers found that from 2000 to 2008, the use of IMRT vs. conformal therapy rose from 0.15% to 95.9%. In addition, they found that men were less likely to receive diagnosis of hip fracture and gastrointestinal adverse effects when treated with IMRT, but were likely to be diagnosed with erectile dysfunction, and were almost 20% less likely to require additional cancer therapy.

In the propensity score-matched comparison between IMRT and proton therapy (n = 1,368), the team discovered that patients who received IMRT were 34% less likely to have gastrointestinal side effects than patients receiving proton therapy. Between IMRT and proton therapy, the researchers found no considerable differences in rates of other side effects or additional therapies.

The researchers explain:

“Proton therapy is a high-profile, high-cost prostate cancer treatment. Since 2007, multiple proton facilities have been built, and direct-to-consumer advertising is likely to lead to a substantial increase in use.

Overall, our results do not clearly demonstrate a clinical benefit to support the recent increase in proton therapy use for prostate cancer.”

The results that IMRT patients were less likely to undergo additional cancer therapies, compared with those who received traditional radiation therapy is consistent with using IMRT to deliver dose-escalated therapies and improved cancer control, as shown in randomized trials.

They explain:

“Taken together, these results suggest that IMRT facilitated radiation dose escalation without compromising acceptable long-term morbidity.”

They conclude:

“Comparative effectiveness research in localized prostate cancer treatments is needed because of the large number of men with this disease and the continued trend of a rapid increase in use of newer and costlier treatments with unproven clinical benefit.”

Written By Grace Rattue