Comparative effectiveness of external-beam radiation approaches for prostate cancer

Intensity-modulated radiotherapy (IMRT) is increasingly used to treat localized prostate cancer. Although allowing for the delivery of higher doses of radiation to the prostate, its effectiveness compared with the prior standard three-dimensional conformal therapy (3D-CRT) is uncertain.

To examine the comparative effectiveness of IMRT relative to 3D-CRT.

We performed a population-based cohort study using Surveillance, Epidemiology, and End Results-Medicare data to identify men diagnosed with prostate cancer between 2001 and 2007 who underwent either 3D-CRT (n=6976) or IMRT (n=11 039).

We assessed our main outcomes (ie, the adjusted use of salvage therapy with androgen-deprivation therapy [ADT] and risk of a complication requiring an intervention) using Cox proportional hazards models.

The percentage of men receiving IMRT increased from 9% in 2001 to 93% in 2007. Compared with those treated with 3D-CRT, low-risk patients treated with IMRT had similar likelihoods of using salvage therapy with ADT and similar risks of having a complication requiring an intervention (all p>0.05). Conversely, a subset of higher risk patients treated with IMRT who did not receive concurrent ADT were less likely to use salvage therapy (p=0.02) while maintaining similar complication rates. Because our cohort includes Medicare beneficiaries, our findings may not be generalizable to younger patients.

For a subset of higher risk patients, IMRT appears to show a benefit in terms of reduced salvage therapy without an increase in complications. For other patients, the risks of salvage therapy and complications are comparable between the two modalities.