Perceptions around bone-modifying agent use in patients with bone metastases from breast and castration resistant...

Optimal use of bone-modifying agent (BMA) therapy in patients with bone metastases from breast and castrate-resistant prostate cancer (CRPC) is evolving.

Patients receiving BMA for bone metastases from breast or CRPC were surveyed. Information was collected on patient and disease characteristics, BMA treatments and perceptions regarding BMA benefits and side effects. Interest in participation in trials of de-escalated BMA therapy was also gauged.

Of 220 patients contacted, 172 eligible patients responded (response rate 78%). Median age was 67 (range: 21-91); 137 (80%) had breast cancer and 35 (20%) CRPC. Symptomatic skeletal events (SSEs) occurred prior to starting BMAs in 61% (84/137) of breast and 48% (17/35) of CRPC patients. Among breast cancer patients, 47, 33 and 13% received zoledronate, pamidronate and denosumab, respectively. Eighty-five percent (30/35) of CRPC patients received denosumab. De-escalation of therapy was more common among breast cancer patients. Although most patients correctly reported the goals of BMA therapy were to "help stop fractures" (62%) and "[improve] quality of life" (63%), 46.5% felt it prolonged survival and 54% felt it reduced bone progression. Most respondents (102/129, 79%) were comfortable with de-escalating to 6-monthly treatment after 2 years of BMA therapy. Patients considered the most important endpoints of de-escalation studies to be "stability of bone metastases" (45%), "quality of life" (22%) and "SSE rates" (14%).

Twelve weekly BMA was more common in breast than in prostate cancer. There remain misconceptions about the benefits of BMAs, highlighting potential gaps in patient education. Patients were interested in further BMA de-escalation after 2 years of prior BMA and provided study endpoints that were most important to them.