Addendum to the previous paper: risk to bone from present 224Ra therapy

Abstract

Present 224Ra treatment for ankylosing spondylitis in Germany consists of 10 weekly intravenous injections, each of 28 µCi 224Ra, giving a cumulative dose of about 56 rad to the marrowfree skeleton of a reference 70-kg man. Among the 224Ra patients followed by Professor Heinz Spiess (mostly at high doses), 54 cases of bone sarcoma have occurred, but none below 90 rad. Dr. Fritz Schales ascertained the health status of about 1170 ankylosing spondylitis patients with skeletal doses from 224Ra below 90 rad (mean ~ 56 rad). The average follow up time of these patients was about 12 years. Dr. Schales found 1 case of reticulum cell sarcoma of bone marrow, at an average skeletal dose between 60 and 112 rad. The bone sarcoma risk throughout lifetime, following present 224Ra treatment, is calculated to be between lower and upper limits (P = 0.05) of 0 and 0.6% if one skeletal sarcoma has occurred in the 1170 patients below 90 rad, or between 0 and 0.4%, if no sarcomas have occurred. No assessment has been made of the possible risk from other effects, such as kidney diseases, liver diseases, and cataracts.