Case A: A female patient (age 77 years, salivary duct carcinoma, KPS 60) was referred to the orthopedic surgeon because of a large painful lytic metastasis in her femur (pain score 8 on a scale of 0 to 10). The orthopedic surgeon suggested planning a prophylactic stabilizing surgery. However, the patient hesitated; hence, a BOS score was requested. The BOS score indicated a high fracture risk, which was discussed with the patient by the orthopedic surgeon and the radiation oncologist. It convinced the patient to undergo the prophylactic stabilizing surgery. One day prior to the scheduled surgery, she fractured her femur while stepping out of her bed. The location of the fracture was similar to the weakest location of the bone indicated by the BOS score. The fracture was treated during surgery. Two months later, she passed away.	Case B: A female patient (age 76 years, breast cancer, KPS 80) visited the radiation oncologist because of a painful lytic metastasis in the femoral head (pain score 5 on a scale of 0 to 10). The radiation oncologist estimated the fracture risk as low and requested a BOS score, which also indicated a low fracture risk. The patient was treated with 1 × 8 Gy radiotherapy. After a follow-up of six months, the patient had not developed a fracture and was still alive.	Case C: A female patient (63 years, breast cancer, KPS 80) visited the radiation oncologist because of a painful metastasis in the femoral shaft (pain score 9 on a scale of 0 to 10). The metastases had a mixed appearance but were predominantly lytic. The radiation oncologists initially estimated the fracture risk as low, and the initial plan was to treat the patient with a radiotherapy dose of 1 × 8 Gy. However, the BOS score indicated a moderate risk of fracture. The patient was, therefore, treated with 2 × 8 Gy radiotherapy with the aim to induce remineralization of the bone. After six months, the patient had not developed a fracture and was still alive.
BOS score of Femur A depicted relative to patients in the BOS database	BOS score of Femur B depicted relative to patients in the BOS database	BOS score of Femur C depicted relative to patients in the BOS database
Weakest location of the bone ATTENTION: Fracture localization by experimental fracturing in computer model does not necessarily coincide with metastatic location	Weakest location of the bone ATTENTION: Fracture localization by experimental fracturing in computer model does not necessarily coincide with metastatic location	Weakest location of the bone ATTENTION: Fracture localization by experimental fracturing in computer model does not necessarily coincide with metastatic location