Intensity modulated radiation therapy replaces 3-dimensional conformal radiotherapy as prostate cancer treatment

Abstract

Purpose: We describe trends in the use of intensity modulated radiotherapy vs 3-dimensional conformal radiotherapy for prostate cancer and identified predictors of intensity modulated radiotherapy use.

Materials and methods: From the SEER (Surveillance, Epidemiology and End Results)-Medicare database we identified 52,290 men with incident nonmetastatic prostate cancer from 2000 to 2007 who were treated with radiotherapy. We tracked trends in the use of intensity modulated radiotherapy, 3-dimensional conformal radiotherapy, brachytherapy and combinations. Patient demographic and clinical characteristics were described and compared using chi-square and multivariate logistic regression. Trends at the place of service were also examined.

Results: Intensity modulated radiotherapy use increased from 1% of all radiotherapy in 2000 to 70% in 2007. Three-dimensional conformal radiotherapy use decreased from 75% to 12%. Most cases were treated with intensity modulated radiotherapy monotherapy. In 2007, 12% of the cohort received intensity modulated radiotherapy plus brachytherapy. In 2005, 81% of all external radiation was given as intensity modulated radiotherapy. Except for geography there were minimal differences in patient demographic and clinical characteristics between those treated with 3-dimensional conformal radiotherapy vs intensity modulated radiotherapy. On multivariate analysis significant predictors of the odds of receiving intensity modulated radiotherapy vs 3-dimensional conformal radiotherapy were low Gleason score, high education, white or Asian race and urban place of residence. The odds of receiving intensity modulated radiotherapy varied greatly by registry. A lesser part of the growth in intensity modulated radiotherapy use occurred at freestanding facilities.

Conclusions: Intensity modulated radiotherapy has replaced 3-dimensional conformal radiotherapy as the primary form of external radiation for prostate cancer. The choice of intensity modulated radiotherapy over 3-dimensional conformal radiotherapy is not related to common clinical factors such as age, comorbidities or tumor aggressiveness. Although geographic variations exist, by 2007 intensity modulated radiotherapy dominated in all regions studied.