The debate about how best to treat certain prostate cancer patients – if at all – might now be put partially to rest with newly released data from what the American Society for Radiation Oncology (ASTRO; Fairfax, Virginia) is calling a "practice-changing cancer study." The principal investigator from the largest randomized trial of its kind has found that short-term hormone therapy given prior to and during intermediate dose radiation treatment for men with early stage prostate cancer increases their chance of living longer.
"There is certainly the sentiment that perhaps prostate cancer patients are over treated or that they don't need such aggressive treatment, but here you have a large study that shows a survival benefit from giving more aggressive treatment," Christopher Jones, MD, author of the study and a radiation oncologist at Radiological Associates of Sacramento (Sacramento, California), told Medical Device Daily. "This study would not support the contention not to treat because this study showed that, overall in a large group of patients, men had a higher chance of living at eight to 12 years with a more aggressive form of treatment."
Although considered statistically significant, that increased chance isn't dramatic. With the protocol now recommended by Jones and his team, a man's chance of living at 10 years would increase from 57% to 62%. The results were released in a late-breaking session at ASTRO's annual meeting being held this week in Chicago.
Prior to this study, it was unclear whether combining hormone therapy with radiation for intermediate-risk prostate cancer patients improves survival.
The phase III Radiation Therapy Oncology Group (RTOG) study included 2,000 low- and intermediate-risk patients enrolled from October 1994 to April 2001. It followed men with early stage prostate cancer for more than nine years. A total of 1,979 eligible men who had cancer confined to the prostate and a PSA less than or equal to 20 were randomized to receive total androgen deprivation therapy for two months prior to and two months during radiation treatment, or to receive only radiation therapy.
"As the prostate-specific antigen (PSA) test started to become more prevalent, we opened the study in 1994 looking at early stage disease," Jones said. "Since the study opened, we've learned more about what truly is low-, intermediate- and high-risk disease. Now we have different definitions of risk. We actually now have modern definitions of what is low-, intermediate- and high-risk."
As part of the study, Jones' group created new guidelines to clarify a patient's risk status based on a combination of scores including the PSA, Gleason (a method of prostate cancer tissue grading) and the traditional tumor-node-metastasis staging system. Patients are categorized into low, intermediate or high risk groups.
The survival benefit from hormones appeared greatest in the intermediate-risk group.
In the study, short-term hormone therapy was added to what was then the standard radiation treatment for prostate cancer, which involved slightly lower doses of radiation than are currently used today with newer techniques, such as intensity modulated radiation therapy (IMRT).
"We looked at overall survival, the primary endpoint, and we met that primary endpoint, which demonstrated improvement in overall survival," Jones said. "You're never certain you're going to get a survival benefit."
When the study was initiated radiation therapy doses were lower than what's delivered now with more advanced radiation therapies.
"We've had a lot of improvement in technique in radiation including IMRT, image-guided radiation therapy (IGRT) and techniques such as doing low-dose permanent seed implants ... all techniques that have allowed us to safely deliver higher doses and other studies show these higher doses give even better results."
Now that it's known that a short course of hormonal therapy added to radiation improves survival, the next question is whether or not the higher doses of radiation would also benefit from the addition of hormonal therapy.
An RTOG successor study has been launched to answer that question.
Jones stressed that these are just guidelines which must be adapted to a patient's particular condition. Treatment will always vary based on age and other health considerations.
Jones said an added bonus from the study was the fact that there was a significant, albeit unplanned, contingent of African American patients.
"We had nearly 400 African Americans and were able to show that the benefit of adding hormone therapy was the same as it was for Caucasian patients," Jones said. "It was nice to have a large enough cohort of patients to show that. We've assumed that it was the same for different racial groups, but it was a nice piece of data to find."
The study was funded by the National Cancer Institute. RTOG is administered by the American College of Radiology (ACR; Philadelphia).
Lynn Yoffee, 770-361-4789;