Cancer and osteoporosis have high incidence rates in older populations. However, the treatment of osteoporosis among cancer patients has not been adequately described. Our purpose was to clarify the current practice patterns of osteoporosis treatment among cancer patients in an academic cancer center, and to analyze the efficacy of treatment interventions. Patient records from April 2009 to March 2018 were retrospectively reviewed, and the study included a total of 316 cancer patients with osteoporosis. After patients' data extraction, the patients were divided into two groups, with (n = 144) or without treatment (n = 172), and compared the outcomes of these groups to evaluate the medication effect. The primary outcome was new radiographic fragility fractures during the study period. The related factors associated with fracture injuries and the rate of adverse events, such as osteonecrosis in the jaw and atypical femoral fractures, were analyzed. The rate of treatment intervention was 45.6% among the patient groups. Among patients in the study group, breast cancer patients (n = 107) were mostly treated (n = 79, 73.8%) with oral bisphosphonate. A significant difference in new fracture rate was observed between the two groups (treatment group, 30.6%; non-treatment group, 54.7%), and the risk of fracture was 42% lower in the treatment group (hazard ratio, 0.58; 95% confidence interval, 0.39-0.86; p<0.05). Previous chemotherapy, steroid use, and older age were significantly associated with increased rate of new fragility fractures. The adverse event rate was 3.5% (presented in five cases). Older cancer patients who receive chemotherapy or steroids are strongly recommended undergo bone quality assessment and appropriate osteoporosis treatment to improve their prognosis.