Three Cases of Intra-articular Metastasis of the Shoulder From Lung Cancer Successfully Treated With Palliative...

Intra-articular metastasis of the shoulder (IMS) is extremely rare. Here, we report three cases of IMS from lung cancer treated with stereotactic body radiotherapy (SBRT) using CyberKnife. Case 1 involved a 50-year-old man with IMS of small-cell lung cancer who developed right shoulder pain that worsened over two weeks. The IMS was treated with SBRT in five fractions over eight days (treatment volume: 19.4 mL; prescribed dose: 30 Gy; maximum dose: 51.7 Gy; treatment time: 35 minutes per fraction). Pain relief occurred immediately and resolved completely within 10 days of initiating SBRT. Pain did not recur until the patient died five months later. Case 2 involved a 66-year-old woman with IMS of lung adenocarcinoma who developed left shoulder pain that worsened over one month. The IMS was treated with SBRT in three fractions over three days (treatment volume: 7.5 mL; prescribed dose: 30 Gy; maximum dose: 44.1 Gy; treatment time: 37 minutes per fraction). Pain relief occurred immediately and resolved completely within four days of initiating SBRT. The pain did not recur until the patient died 22 months later. Case 3 involved a 73-year-old man with IMS of lung adenocarcinoma who developed right shoulder pain that worsened over one month. The IMS was treated with SBRT in three fractions over four days (treatment volume: 6.1 mL; prescribed dose: 30 Gy; maximum dose: 46.2 Gy; treatment time: 32 minutes per fraction). Pain relief occurred immediately and resolved completely within one week of initiating SBRT. The pain has not recurred in the nine years and three months since SBRT. No SBRT-related adverse events occurred in any of the cases. IMS should be included in the differential diagnosis of cancer patients with shoulder pain. SBRT may be a useful palliative treatment for such cases.