Impact of treatment delay of multiple myeloma bone disease on later myeloma-related skeletal events and outcome.

Limited data exists on the effect of treatment delay of multiple myeloma (MM) bone disease on the disease course. In this real-world analysis of 625 patients with newly diagnosed MM (NDMM) we aimed to investigate the impact of delay in starting bone disease treatment on later skeletal events and outcome. Altogether 480 (76.8 %) patients had bone disease at the diagnosis, 282 (45.1 %) patients had a fracture at diagnosis, and 181 (29.1 %) patients had a later fracture during the follow-up. A delay in the initiation of treatment of bone disease was experienced by 221 (35.4 %) patients and tooth extraction was a main reason for the delay. Patients with a delay seemed to experience earlier and more frequent later fractures. Also, a fracture (p = 0.003) or bone disease (p < 0.001) at diagnosis predicted earlier incidence of later fractures. As a bone targeted treatment, altogether 363 (58.1 %) patients received zoledronic acid, 81 (13.0 %) denosumab and 134 (21.4 %) other bone-targeted treatment. Patients treated with denosumab had poorer overall survival (OS) (p < 0.001) and experienced earlier later fractures (p = 0.003). Multivariate analysis showed that bone disease at diagnosis (p = 0.043) and given bone disease treatment (p = 0.023) significantly impacted on the time to next fracture. Regarding OS, delay in osteoprotective treatment (p = 0.004) and time of the diagnosis (p < 0.001) were significant factors in multivariate analysis. To conclude, this study suggests that early initiation of bone disease treatment seemed to prevent later fractures. These findings highlight the importance of patients' rapid access to a dentist and the start of bone targeted treatment without delay after a myeloma diagnosis.