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IMRT versus CRT after Prostatectomy

Authors

Tori Socha

The most common malignant neoplasm in American men is prostate cancer; there are 240,000 cases of prostate cancer and 30,000 deaths from the disease per year. Emerging technologies such as intensity-modulated radiotherapy (IMRT) have been quickly adopted for clinical use. The use of new technologies such as IMRT in treating prostate cancer has increased healthcare costs by $350 million a year, according to a recent study.

According to researchers, there is a lack of comparative effectiveness research of therapies for prostate cancer. The Institute of Medicine has named the management of localized prostate cancer as one of its top priorities for comparative effectiveness research.

Radiotherapy has the potential to damage organs adjacent to the prostate leading to long-term morbidity. Because the intensity of the beam is varied at each treatment beam angle in IMRT, the radiation dose to the adjacent organs may be reduced compared with older conformal radiotherapy (CRT).

Radiotherapy is indicated after prostatectomy in patients with adverse pathologic features as well as in those with recurrent disease. In this setting, because the prostate has been removed, the radiation dose is lower compared with primary treatment, calling into question the potential benefit of IMRT versus CRT in terms of reducing treatment-related morbidity.

Researchers recently conducted a study designed to identify the patterns of post-prostatectomy radiation techniques and to compare the morbidity and cancer control outcomes of IMRT versus CRT. Study results were reported in JAMA Internal Medicine [2013;173(12):1136-1143].

The researchers utilized data from the Surveillance, Epidemiology and End Results (SEER)-Medicare Linked Database to identify patients with a diagnosis of prostate cancer who had received radiotherapy within 3 years following prostatectomy. The study cohort included 457 men who received IMRT and 557 who received CRT between 2002 and 2007. The groups were compared using claims through 2009. Propensity score methods were used to balance baseline characteristics and estimate adjusted incidence rate ratios (RRs).

Among the patients who received postprostatectomy radiotherapy, the use of IMRT versus CRT increased from zero in 2000 to 82.1% in 2009. Rates of use of IMRT varied by geographic region and increased in metropolitan versus nonmetropolitan areas.

Adjusted analysis results did not find significant differences between the 2 groups in GI or urinary diagnoses or procedures, or in erectile dysfunction. There was also no significant difference in receipt of subsequent cancer therapies that may suggest a recurrence of prostate cancer.

Limitations to the study cited by the authors included the use of SEER-Medicare data; because claims files are not designed to provide detailed clinical information, outcomes examined may be subject to misclassification and certain outcomes such as erectile dysfunction may be underreported. In addition, it is possible that patients receiving a novel technique may have had falsely elevated expectations of outcomes and thus were more likely to report morbidity following treatment. The authors also noted that treatment choice may have led to confounding. Finally, the study is limited by the need to exclude patients with discontinuous Medicare coverage.

In summary, the authors stated, “Postprostatectomy IMRT and CRT achieved similar morbidity and cancer control outcomes. The potential clinical benefit of IMRT in this setting is unclear. Given that IMRT is more expensive, its use for postprostatectomy radiotherapy may not be cost-effective compared with CRT, although formal analysis is needed.”

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