Long-term Morbidity of Intensity Modulated vs Conformal Radiation Therapy (RT) for Prostate Cancer: A SEER-Medicare Analysis
Reporter: Surbhi Grover, MD
The Abramson Cancer Center of the University of Pennsylvania
Last Modified: October 4, 2011
Presenter: N. Sheets Presenter's Affiliation: University of North Carolina, Chapel Hill, NC
There is a rapid uptake of intensity modulated radiation therapy (IMRT) for treatment of prostate cancer because of potential reduction of dose to normal tissue and hence reduction in morbidity related to treatment.
Although there is rapid implementation of new technology, comparative effectiveness data looking at different modalities is lacking.
Authors of this study evaluated morbidity of IMRT vs non-IMRT treatment of prostate cancer in definitive and post-operative setting using the Surveillance, Epidemiology, and End Result (SEER)-Medicare linked database.
Between 2000-2005, authors identified about 40,000 patients who received IMRT using CPT codes.
Patients were divided in two groups:
Patients who received definitive treatment within 1 year of diagnosis (n=38,159)
Patients who received post-operative radiation therapy, treated within three years after surgery (n=1,503)
Co-morbidity scores were calculated and data on interventions after radiation treatment were assessed in both definitive and post-operative patients in IMRT and non-IMRT groups.
Patient in the IMRT and non-IMRT groups were matching using propensity score analysis.
In the definitive group, 6666 patients received IMRT and 6310 patients received conformal radiation therapy. Follow up was 73 months for non-IMRT patients vs 53 months for IMRT patients.
There were lower rates of hip fractures and bowel morbidity in the IMRT group. However, erectile dysfunction was worse in the IMRT group. Patients treated with IMRT required less additional cancer treatment compared to patients with non-IMRT.
In the post-operative group, 505 patient got IMRT and 663 patients got non-IMRT treatment.
With the follow up of 56 months for non-IMRT patients vs 30 month for IMRT patients, there was no significant difference in morbidity in the IMRT and non-IMRT group.
There was a suggestion of higher use of additional cancer therapy in IMRT group. Also, there were higher rates of erectile dysfunction noted in IMRT group.
There was a rapid adoption of IMRT noted in both definitive and post-operative setting.
There has been a rapid uptake of IMRT for treatment of prostate cancer.
In definitive treatment, there are lower rates of additional cancer treatment needed with IMRT likely because of dose escalation with IMRT.
In post-operative setting, higher rates of additional cancer therapy may be needed in IMRT group. This needs to be assessed in prospective randomized trials.
Higher rates of erectile dysfunction in the post-operative patients is likely residual from prostatectomy, therefore it is difficult to interpret differences in erectile dysfunction associated with radiation modalities.
Clinical and Scientific Implications
This study is an attempt to use SEER data to describe outcomes between IMRT and non-IMRT treatment. There are limitations to this study because of the data available in SEER. Although one can look at additional procedures and survival, toxicity data is limited and evaluation of this data should be taken with caution. It is interesting to see that in the definitive setting, patients treated with IMRT have fewer additional procedures. However, the follow up is shorter in the IMRT group which may account for some of this difference.
Oct 4, 2011 - Treatment of localized prostate cancer using intensity modulated radiation therapy is associated with a considerable reduction in late bowel and rectal side effects and significantly decreased rectal and bladder toxicity compared to three-dimensional conformal radiation therapy, according to a study presented the annual meeting of the American Society for Radiation Oncology, held from Oct. 2 to 6 in Miami Beach.