Radiation therapy utilisation in patients with bone metastases secondary to prostate cancer: A multicenter study

Bone metastases (BMs) occur in 65%–90% of patients affected by advanced breast cancer (BC) or prostate cancer (PC; Parker et al., 2013). Recently, Lebret et al. (2016) have assessed the management of BMs in patients with solid tumours and haematological malignancies across five European countries, for evaluating the use of bisphosphonates. Prompted by their study, we wish to assess whether an increase both in incidence and in prevalence of PC corresponds to a numerical increase of radiation treatments for BMs. We have retrospectively collected data of all patients who underwent radiotherapy for BMs from all tumours (ATBMs) in three Sicilian provinces (Messina, Catania and Ragusa), in a 10year period. The study period was from January 2004 to December 2013. We retrieved patients’ data from the registries of every radiation department operating in the three provinces. Data on PC incidence and prevalence were collected from the database “tumori.net”, which reports data up to 2015. Data on the number of inhabitants were retrieved from database of the Italian National Institute of Statistics (Istituto Nazionale di Statistica; Sicilia). In the 10year period, we identified 5,775 patients affected by BMs who underwent radiation treatments. 1,307/5,775 (or 22.63%) of these patients had prostate cancer BMs (PCBMs), with a mean of 130.7 patients per year, ranging from 102 in 2005 to 155 in 2009 (vs. mean of 200.9 patients per year for breast cancer BMs, p < .001 by ANOVA test). Difference in the percentage of treatments per year for ATBMs with respect to treatments for PCBMs reached statistical significance (χ2 = 23.545, p = .005). The total annual number of patients who underwent radiation therapy for ATBMs increased linearly from 534 in 2004 to 686 in 2013 (r = .723, p = .018), whereas no statistically significant increase was found for the treatments for PCBMs in the same period of time (r = .527, p = .118) (Figure 1). In the three provinces, there were 981,571 men living in 2004 compared to 983,756 in 2013 (r = .323, p = .363). In Sicily, the number of new diagnoses of PC increased linearly from 2,349 in 2004 to 2,899 in 2013 (r = .998, p < .001). Also prevalence increased linearly, with 9,546 cases of PC in 2004 and 18,704 cases of PC in 2013 (r = .999, p < .001) (Figure 2). In term of percentages, there was a 21% increase of the incidence that was 97.86/100,000 in 2004 and 119.05/100,000 in 2013; regarding the prevalence, it was 397.64/100,000 in 2004 and 767.97/100,000 in 2013, resulting in a 93.13% increase from 2004 to 2013. We think that the absence of increment in radiation treatments for PCBMs could be caused by novel therapeutic approaches, i.e., bisphosphonates and denosumab, which reduce skeletalrelated events (Lipton et al., 2015; Maisano, Pergolizzi & Cascinu, 2001). Theoretically, the increment both of incidence and prevalence in the examined Sicilian population of PC would have to be resulted in an increase in patients suffering for BMs and therefore in an increment of radiation treatments, as reported from Pergolizzi, Pontoriero, Delia & Santacaterina (2004) on the procedures for BMs in the same macroarea and including all departments operating in 2000, but it could be possible also that in our provinces some patients with painful BMs are not referred to radiation departments; this is only an hypothesis and it is conjectural.