Benefits of radiation techniques in prostate cancer ‘need clarifying’
MedWire News: Intensity-modulated radiation therapy (IMRT) may improve clinical outcomes in men with nonmetastatic prostate cancer to a greater extent than conformal RT (CRT) or proton therapy (PT), suggest study findings.
Compared with CRT, IMRT was associated with fewer diagnoses of gastrointestinal morbidity and hip fractures as well as a reduced need for additional cancer therapy, although it was also associated with an increased rate of erectile dysfunction.
In addition, IMRT was associated with less gastrointestinal morbidity than PT.
Recent advances in technology have led to the rapid adoption of new radiation therapies for the treatment of prostate cancer. IMRT has gradually replaced the older technique of CRT and there has also been a substantial increase in the use of PT since 2007.
"The potential advantage of IMRT and proton therapy compared with conformal radiation therapy is their ability to deliver high radiation doses to the prostate while minimizing doses to surrounding organs," explain Ronald Chen (University of North Carolina hospitals, Chapel Hill, USA) and colleagues.
"However, the clinical benefit from these newer treatments is unproven, and comparative effectiveness research examining different radiation techniques is lacking," they add.
Using the Surveillance, Epidemiology, and End Results (SEER)-Medicare-linked database, the researchers examined clinical outcomes in 13,660 men newly diagnosed with nonmetastatic prostate cancer who were treated with IMRT (n=6666), CRT (n=6310), or PT (n=684) between 2000 and 2009.
They also identified men requiring additional cancer therapy 9 months or more after initiation of RT as an indicator of disease recurrence.
Men treated with IMRT, CRT, or PT were followed up over a median of 44, 64, and 50 months, respectively.
The researchers report that the use of IMRT versus CRT for the treatment of nonmetastatic prostate cancer increased significantly from 0.15% in 2000 to 95.9% in 2008.
Propensity-matched analysis showed that compared with patients who underwent CRT, those treated with IMRT were 9% less likely to receive a diagnosis of gastrointestinal morbidity and 22% less likely to fracture a hip, while they were 12% more likely to receive a diagnosis of erectile dysfunction. In addition, men treated with IMRT were 19% less likely to receive additional cancer therapy.
The authors also found that men treated with PT were 34% more likely to receive a diagnosis of gastrointestinal morbidity than those treated with IMRT, while rates of additional cancer therapy were no different between the two groups.
"Overall our results do not clearly demonstrate a clinical benefit to support the recent increase in proton therapy use for prostate cancer," writes the team in JAMA.
The researchers say that to their knowledge, this is the first study to examine morbidity and disease control outcomes among the three most commonly used radiation techniques for prostate cancer.
"Because IMRT and proton therapy are relatively new technologies, several more years of use and patient follow-up are needed to examine comparative survival outcomes," they conclude.
By Sally Robertson