Comparative risks for cancer associated with use of calcitonin, bisphosphonates or selective estrogen receptor modulators among osteoporosis patients: a population-based cohort study.

Background: This population-based cohort study was to compare the risks of incident cancer in osteoporosis patients who used bisphosphonates, calcitonin or selective estrogen receptor modulators (SERMs).

Methods: We identified 9995 patients who were diagnosed with osteoporosis and prescribed osteoporosis drugs (bisphosphonate (n = 4675), calcitonin (n = 3993) and SERMs (n = 1327)) between 1 January 2000 and 31 December 2006 in Taiwan's National Health Insurance Research Database. Date of first prescription of osteoporosis drugs was assigned as the index date. The outcome measurement was incident cancer, defined by a first-ever inpatient visit with a primary diagnosis of cancer. All patients were followed until the occurrence of cancer. For those who did not develop cancer, we censored them at 1 year after their last prescription of osteoporosis drugs. Cox proportional hazard models were used to examine the association between risk of cancer and use of calcitonin, bisphosphonates or SERMs.

Results: The incidence rate of cancer was 68.8, 34.0 and 29.6 per 1000 person years in the calcitonin, SERMs and bisphosphonate cohorts, respectively. Compared with bisphosphonate users, calcitonin users were associated with an increased risk of cancer (adjusted hazard ratio (HR) 2.11, 95% confidence interval (CI) 2.01-2.21, P < 0.001). SERM users were associated with an increased risk of cancer (adjusted HR 1.20, 95% CI 1.13-1.28, P < 0.001).

Conclusion: Our findings suggest that calcitonin is associated with an increased risk of cancer than bisphosphonate, supporting the recent warning issued by the European Medicines Agency and US Food and Drug Administration. SERMs is found to be associated with an increased risk of cancer than bisphosphonate.