NO ADVANTAGE OF IMRT FOR PROSTATE CANCER
In the past decade, when providing radiotherapy
to men after prostatectomy, radiation oncologists have rapidly switched
from an old radiotherapy to a newer, more expensive one, according to
the results of a new study.
But the switch "may not be based in clinical reality," researchers report.
The use of intensity-modulated radiotherapy (IMRT) in the United States increased from 0% in 2000 to 82.1% in 2009, according to the study, which was published online May 20 in JAMA Internal Medicine.
However, the researchers found that outcomes with IMRT are not better than those with the older less-expensive conformal radiotherapy (CRT) when used adjunctively or as salvage therapy after prostatectomy.
"I think our study provides some new information for patients and physicians to consider," said senior author Ronald C. Chen, MD, MPH, assistant professor in the Department of Radiation Oncology at the University of North Carolina at Chapel Hill.
Presumably, those physicians include Dr. Chen and his colleagues. Their center currently uses IMRT in this setting, he told Medscape Medical News in an email.
"Most radiation facilities across the United States are capable of giving both IMRT and CRT. Therefore, if indeed more studies demonstrate similar outcomes after surgery, a reversal of the trend is possible," Dr. Chen explained.
The study results seem "counterintuitive" because IMRT is "more precise," said Anurag Singh, MD, who was asked by Medscape Medical News to comment of the findings. Dr. Singh is professor of oncology and director of clinical radiation research at the Roswell Park Cancer Institute in Buffalo, New York, and was not involved in the study.
However, Dr. Singh explained that a "countervailing factor is that in the postprostatectomy setting, the area at risk is not necessarily well defined. So there is some designed uncertainty in the prostate-bed delineation." This uncertainty could level the playing field between the 2 radiotherapies, he suggested.
Dr. Singh praised the study, but also said that it might be underpowered because the baseline expectation for significant toxicities was small (3.3%) and a larger patient sample was likely needed to detect differences between the 2 radiotherapies.
He also said that postprostatectomy patients in need of radiotherapy are generally treated with IMRT at Roswell Park.
The Specifics
According to Dr. Chen and colleagues, the role of radiotherapy is "well established" after surgery for men who have either adverse pathologic features or recurrent prostate cancer; however, the "optimal radiation technique is not."
To rectify this, they analyzed records from the Surveillance, Epidemiology and End Results–Medicare-linked database from 2002 to 2007. Of the 97,000 men who received radiotherapy within 3 years of their prostatectomy, 457 IMRT patients and 557 CRT patients met the inclusion criteria (one of which was being at least 66 years of age).
There was no significant difference in rates of long-term gastrointestinal morbidity (relative risk [RR], 0.95), urinary nonincontinent morbidity (RR, 0.93), urinary incontinence (RR, 0.98), or erectile dysfunction (RR, 0.85) between the 2 groups. There was also no significant difference in subsequent treatment for recurrent disease (RR, 1.31).
Median follow-up was 45.6 months for the CRT patients and 27.5 months for the IMRT patients.
The researchers controlled for variables such as the use of androgen-deprivation therapy and surgical technique (including minimally invasive prostatectomy).
This is the largest study to date to compare patient outcomes with IMRT and CRT, they note. It is also the first to demonstrate how rapidly American radiation oncologists switched from the old technology to the new.
Because there are no randomized controlled trials comparing CRT and IMRT, these data are important, Dr. Chen and colleagues note.
"The potential clinical benefit of IMRT compared with CRT in this setting is unclear," they conclude.
What is clear is that IMRT is expensive; it costs about $15,000 to $20,000 more than standard therapies, as reported by Medscape Medical News. Critics have said that financial incentives are driving overuse of this newer technology.
Key Point: No Clear Role for Dose Escalation
Dr. Chen and his colleagues are not IMRT bashers; in fact, they are anything but.
In a previous study, they demonstrated that IMRT, when used as a primary therapy for prostate cancer, is superior to CRT in terms of morbidity and cancer control (JAMA. 2012;307:1611-1120). In that study, the researchers explain that the better efficacy was "likely due to an ability of IMRT to safely allow higher radiation doses to be delivered to the prostate ('dose escalated' radiation)."
But the postprostatectomy setting is a different clinical scenario — the radiation dose is lower than in primary treatment. Thus, the advantage of IMRT (dose escalation) might be negated, Dr. Chen and colleagues write. The lower dose might be an equalizer.
Other studies have found that CRT, when used after surgery, has a low rate (<5 adverse="" and="" effects="" em="" gastrointestinal="" long-term="" of="" urinary="">J Clin Oncol
But the switch "may not be based in clinical reality," researchers report.
The use of intensity-modulated radiotherapy (IMRT) in the United States increased from 0% in 2000 to 82.1% in 2009, according to the study, which was published online May 20 in JAMA Internal Medicine.
However, the researchers found that outcomes with IMRT are not better than those with the older less-expensive conformal radiotherapy (CRT) when used adjunctively or as salvage therapy after prostatectomy.
"I think our study provides some new information for patients and physicians to consider," said senior author Ronald C. Chen, MD, MPH, assistant professor in the Department of Radiation Oncology at the University of North Carolina at Chapel Hill.
Presumably, those physicians include Dr. Chen and his colleagues. Their center currently uses IMRT in this setting, he told Medscape Medical News in an email.
"Most radiation facilities across the United States are capable of giving both IMRT and CRT. Therefore, if indeed more studies demonstrate similar outcomes after surgery, a reversal of the trend is possible," Dr. Chen explained.
The study results seem "counterintuitive" because IMRT is "more precise," said Anurag Singh, MD, who was asked by Medscape Medical News to comment of the findings. Dr. Singh is professor of oncology and director of clinical radiation research at the Roswell Park Cancer Institute in Buffalo, New York, and was not involved in the study.
However, Dr. Singh explained that a "countervailing factor is that in the postprostatectomy setting, the area at risk is not necessarily well defined. So there is some designed uncertainty in the prostate-bed delineation." This uncertainty could level the playing field between the 2 radiotherapies, he suggested.
Dr. Singh praised the study, but also said that it might be underpowered because the baseline expectation for significant toxicities was small (3.3%) and a larger patient sample was likely needed to detect differences between the 2 radiotherapies.
He also said that postprostatectomy patients in need of radiotherapy are generally treated with IMRT at Roswell Park.
The Specifics
According to Dr. Chen and colleagues, the role of radiotherapy is "well established" after surgery for men who have either adverse pathologic features or recurrent prostate cancer; however, the "optimal radiation technique is not."
To rectify this, they analyzed records from the Surveillance, Epidemiology and End Results–Medicare-linked database from 2002 to 2007. Of the 97,000 men who received radiotherapy within 3 years of their prostatectomy, 457 IMRT patients and 557 CRT patients met the inclusion criteria (one of which was being at least 66 years of age).
There was no significant difference in rates of long-term gastrointestinal morbidity (relative risk [RR], 0.95), urinary nonincontinent morbidity (RR, 0.93), urinary incontinence (RR, 0.98), or erectile dysfunction (RR, 0.85) between the 2 groups. There was also no significant difference in subsequent treatment for recurrent disease (RR, 1.31).
Median follow-up was 45.6 months for the CRT patients and 27.5 months for the IMRT patients.
The researchers controlled for variables such as the use of androgen-deprivation therapy and surgical technique (including minimally invasive prostatectomy).
This is the largest study to date to compare patient outcomes with IMRT and CRT, they note. It is also the first to demonstrate how rapidly American radiation oncologists switched from the old technology to the new.
Because there are no randomized controlled trials comparing CRT and IMRT, these data are important, Dr. Chen and colleagues note.
"The potential clinical benefit of IMRT compared with CRT in this setting is unclear," they conclude.
What is clear is that IMRT is expensive; it costs about $15,000 to $20,000 more than standard therapies, as reported by Medscape Medical News. Critics have said that financial incentives are driving overuse of this newer technology.
Key Point: No Clear Role for Dose Escalation
Dr. Chen and his colleagues are not IMRT bashers; in fact, they are anything but.
In a previous study, they demonstrated that IMRT, when used as a primary therapy for prostate cancer, is superior to CRT in terms of morbidity and cancer control (JAMA. 2012;307:1611-1120). In that study, the researchers explain that the better efficacy was "likely due to an ability of IMRT to safely allow higher radiation doses to be delivered to the prostate ('dose escalated' radiation)."
But the postprostatectomy setting is a different clinical scenario — the radiation dose is lower than in primary treatment. Thus, the advantage of IMRT (dose escalation) might be negated, Dr. Chen and colleagues write. The lower dose might be an equalizer.
Other studies have found that CRT, when used after surgery, has a low rate (<5 adverse="" and="" effects="" em="" gastrointestinal="" long-term="" of="" urinary="">J Clin Oncol
There is one other sizeable study that compares CRT and IMRT, and it found CRT to have worse GI morbidity (J Clin Oncol. 200927:2924-2930). But it is a single-center study that included patients treated with CRT as early as 1988. Dr. Chen and colleagues suggest that the study is dated because it was conducted before the advent of radiation planning with computed tomography.
The study was funded by the Agency for Healthcare Research and Quality, US Department of Health and Human Services, as part of the DEcIDE program.
JAMA Intern Med. Published online May 20, 2013. Abstract
Δεν υπάρχουν σχόλια:
Δημοσίευση σχολίου