Radioisotope Synovectomy (RS) is defined as the intra-articular injection of radioisotopic agents with the aim of fibrosis on hypertrophic synovium in the target joint for hemophilia. Yttrium90 (Y90) and Rhenium186 (Re186) are approved isotopes in Europe. The only radioisotope which approved in the USA for RS is Phosphorus 32 (P32). We have successfully used Y90 and Re186 for 8 years in target joints of hemophiliac patients. For the last 30 years, no malignant transformation has been reported in hemophilia with RS. However, recently, development of acute lymphoblastic leukemia in two hemophiliac children after RS has been reported in the USA. Even though P32 was the responsible radioisotopic agent, safety concerns have arisen due to exposure to all type of radioisotopic agents which may cause chromosomal breakages (CBs) and oncological transformation. The aim of this prospective and Ethics commitee-approved study was to investigate the early genotoxic effect on peripheral blood lymphocytes induced by Y90 and Re186 in children who underwent RS for chronical synovitis. All patients and parents were informed according to Helsinki Decleration. Thirty-three patients with persistent synovitis (23 hemophilia-A, 9 hemophilia-B,1 FVII deficiency) were enrolled to the study. All patients were male except one case. The mean age was 16.4 ±6.2 years (range:8–40). RS was performed as an outpatient procedure by using Y90 for knees (n=9)(5 mCi) and Re186 for elbows and ankles (n=14)(2 mCi)(CIS Bio International/Gif-sur-Yvett Cedex-France). In 6 patients, both agents were used simultaneously in one session. No radioisotope leakage away from the injection site was observed during and after procedure. Heparinised peripheral blood samples were obtained for lymphocyte cultures from all patients at three different time points (prior to RS, after 3 days and after 90 days). Diepoxybutane (DEB) test was used for the evaluation of chromosomal breakages in patients by culturing their blood along with blood from a sex-matched control with a working solution of 11 ug/ml. Five μl pure DEB was added to 5 ml of sterile dH2O. Afterwards, 10 μl of the first solution was added to 1 ml of sterile dH2O. This is the working solution at 11 ug/ml. A total of 50 metaphases from each culture were examined and scored according to the procedure. All cytogenetic analysis were performed in the Medical Genetics Laboratory of Ege University Hospital. Due to technical problems, parameters of 29 patients were evaluated. Chromosomal breakages (CB) were found in 20 patients prior to treatment. We have found CBs in 4 additional patients after 3 days of RS. However, all these CBs were disappeared 90 days after. CBs were found to be persisted in 17 patients. Mean frequency of CBs was (0.0707±0.0829/1000 cells) and was not significantly increased after 3 days (0.0828±0.0747) but significantly decreased at 90 days (0.0379±0.0456). The difference of the results of two radioisotopes were not significant. In conclusion, although RS with Y90 and Re186 does not seem to induce the genotoxic effects significantly on peripheral blood lymphocytes in hemophilic children, the significant decrease in the number of CBs between the 3rd and 90th days may be accepted as a warning for the requirement of risk/benefit ratios which should be taken into account for any individual patient. Therefore medical treatment in hemophilia for synovitis should be suggested before RS and families should be informed properly.

Disclosures: Off Label Use: As a radioisotopic agent, P 32 is the only approved in the USA. However, Yttrium 90 and Rhenium 186 are not yet approved in the USA..

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