The impact of recombinant parathyroid hormone on malignancies and mortality: 7 years of experience based on nationwide Danish registers

We used Danish registers to identify patients with osteoporosis, who had been treated with parathyroid hormone and evaluated the probability of developing cancer. We did not find an increased risk of cancer among the patients treated with parathyroid hormone. We evaluated the incidences of malignancies and mortality in osteoporotic patients treated with rPTH. Using Danish nationwide registers, we identified patients diagnosed with osteoporosis in the period 1995 through 2010. Each patient treated with rPTH (case) was compared with 10 gender- and age-matched patients who did also have osteoporosis but did not receive rPTH (control). A total of 4,104 cases (80.3 % females) were identified. The mean age at the beginning of rPTH treatment was 70.9 (SD 9.7) years. During a follow-up time of 10,118 person-years for the cases and 88,005 person-years for the controls, a total of 255 cases (6.2 %) compared with 2,103 controls (5.1 %) experienced a cancer (Chi square, p = 0.003). We found an adjusted cancer related HR of 1.1 (95 %CI 0.9-1.4) among the cases. Lung cancer was the only cancer type with a significantly increased rate among patients receiving rPTH (HR 1.7; 95 % CI 1.3-2.3). No cases developed osteosarcomas and nine controls developed osteosarcoma. During follow-up, 627 (15.3 %) cases died and 4,175 (10.2 %) controls died, which yielded an excess mortality risk of 26 % (95 % CI 16-37 %). This could be due to differences in the prevalence of vertebral fractures between the rPTH-treated and non-treated patients. This study did not support the hypothesis describing a possible link between rPTH treatment and the development of cancer. We also conclude that osteosarcoma has not been diagnosed in any Danish patient receiving rPTH since the year 2003 when it was introduced on the market.