Managing Bone Metastases with Denosumab: Real-World Data and Critical Monitoring Points in Breast, Lung, and Prostate Cancers

<i>Background and Objectives</i>: Advanced solid organ tumors, particularly breast, lung, and prostate cancers, frequently metastasize to bone, leading to debilitating skeletal-related events (SREs). Denosumab, a RANKL inhibitor, is crucial in preventing SREs. This study aimed to comparatively evaluate the efficacy and adverse effect profiles of denosumab in patients with bone metastases originating from these three common cancer types. <i>Materials and Methods</i>: This retrospective study included 146 patients treated with denosumab for bone metastases. Data on demographics, SREs before and during denosumab treatment, serum creatinine, calcium, and magnesium levels (at baseline, 3, and 6 months), other adverse effects, and survival were analyzed. <i>Results</i>: Before denosumab, SREs were present in 36.3% of patients (breast: 43.4%, prostate: 28%, lung: 33.8%). During denosumab treatment, SRE rates markedly decreased across all groups (breast: 9.4%, prostate: 16.0%, lung: 8.8%), with no significant intergroup difference in on-treatment SREs. Significant decreases in serum calcium levels were observed at 3 and 6 months post-denosumab initiation in breast (<i>p</i> < 0.0001) and lung cancer patients (<i>p</i> = 0.001). Mean creatinine levels significantly decreased in lung (<i>p</i> < 0.0001) and prostate (<i>p</i> = 0.020) cancer patients at 3 and 6 months. Overall survival significantly differed, with lung cancer patients having the shortest median survival (<i>p</i> < 0.005). <i>Conclusions</i>: Denosumab effectively reduces the incidence of SREs in patients with bone metastases from breast, lung, and prostate cancer. However, clinicians must diligently monitor for hypocalcemia, a notable adverse effect, particularly at 3 and 6 months after starting denosumab, with specific caution warranted in patients with lung cancer.