Association between elcatonin use and cancer risk in Japan: A follow-up study after a randomized, double-blind, placebo-controlled study of once-weekly elcatonin in primary postmenopausal osteoporosis.

Objectives: On July 20, 2012, the European Medicines Agency (EMA) provided a recommendation that limits the long-term use of calcitonin. Based on this recommendation, we investigate the presence or absence of a cancer diagnosis in subjects who participated in the ongoing clinical trial of elcatonin.

Methods: When the EMA gave this recommendation, we were conducting "a 3-year placebo-controlled clinical study for elcatonin" (hereinafter, referred to as "the original study"). In accordance with the recommendation of EMA, we performed an intermediate analysis on the subjects of the original study to assess whether the study could be safely continued. We also added a 2-year follow-up study to investigate the risk of carcinogenesis for 5 years from the start of administration. We compared the risk of carcinogenesis estimated by person-year method in elcatonin group with that in placebo group.

Results: In the original study, there were 433 subjects in the elcatonin group and 437 in the placebo group, of whom 322 and 323, respectively, agreed to participate in the additional follow-up study. The average cancer incidence rate per 100 person-years 5 years from the start of administration was 1.02 in the elcatonin group and 1.08 in the placebo group, respectively, and there was no clear difference.

Conclusions: Since the number of cases in this study was small, we cannot completely deny the cancer risk due to long-term administration of this drug. However, the results do not suggest that once-weekly administration of 20 units of elcatonin increases the carcinogenic risk.