Patterns of stereotactic body radiation therapy: The influence of lung cancer treatment on prostate cancer treatment.

Introduction: Technology availability and prior experience with novel cancer treatments may partially drive their use. We sought to examine this issue in the context of stereotactic body radiation therapy (SBRT) by studying how its use for an established indication (lung cancer) impacts its use for an emerging indication (prostate cancer).

Methods: Using SEER-Medicare from 2007 to 2011, we developed prostate cancer-specific physician-hospital networks. Our primary dependent variable was SBRT use for prostate cancer and our primary independent variable was SBRT use for lung cancer, both at the network level. To assess the influence of SBRT availability and experiential use, we generated predicted probabilities of SBRT use for prostate cancer stratified by a network's use of lung cancer SBRT, adjusting for network characteristics. To assess intensity of use, we examined the correlation between the proportion of prostate cancer patients and lung cancer patients receiving SBRT within a network.

Results: We identified 316 networks that served 41,034 prostate cancer and 83,433 lung cancer patients. A network was significantly more likely to use SBRT for prostate cancer if that network used SBRT for lung cancer (e.g., in 2011, odds ratio [OR] 12.7; 95% confidence interval [CI] 3.9-41.8). The Pearson's correlation between the proportion of prostate cancer patients and lung cancer patients receiving SBRT in a network was 0.34, which was not statistically significant (P = 0.12).

Conclusions: SBRT availability and experiential use for lung cancer influences its use for prostate cancer, but intensity of use for one does not relate to intensity of use for the other.