Top Line: While the use of bisphosphonates in breast cancer has been studied out the wazoo, not so much for prostate cancer.
The Study: Here is a retrospective look at outcomes for 745 men receiving upfront abiraterone for metastatic castrate resistant prostate cancer with (n=216) or without (n=529) bone-modifying agents such as Xgeva (61%) or Zometa (39%). Interestingly, the men on bone-modifying agents had a significantly longer median survival (32 months) than those who weren’t (23 months). This really bore out among those with high-volume disease (n=420) where the difference was 34 versus 20 months. Before you figure this is probably a one-off, it’s actually in-line with a 2015 post-hoc analysis of one of the initial phase 3 trials establishing the efficacy of abiraterone. In contrast, among men with low-volume disease, bone-modifying agents not only showed no association with longer survival but also doubled the risk of skeletal events (i.e., fracture, cord compression or pain requiring palliative radiation). Say what? That’s right, no one seems to know why but these agents were modifying bone in a way that led to more than twice the number of bone complications among men with low-volume disease compared to those who didn’t receive bone resorption inhibitors.
TBL: Bone resorption inhibitors in men with high-volume, mCRPC receiving abiraterone might improve overall survival and reduce the risk of skeletal events. | Francini, JAMA Netw Open 2021