Comparative in vivo and in vitro study of the cytogenetic effects of 153Sm-EDTMP in lymphocytes of patients with bone metastases.

153Sm-EDTMP is a radiopharmaceutical used in nuclear medicine for relief of metastatic bone pain with promising results, but there are few studies about the effects of 1 5 3 Sm-EDTMP in human cells. This study was conducted for the evaluation of the cytogenetic effects of 1 5 3 Sm-EDTMP in blood lymphocytes from patients with bone metastases (without previous radio or chemotherapy), using the chromosome aberration technique. The degree of cytological damage found in in vivo blood cells of patients was compared with those found in in vitro in an adjusted dose-response curve. Blood samples were collected before and 1 hr after the administration of 1 5 3 Sm-EDTMP (about 42.31 MBq/kg). The frequency of structural chromosome aberration per cell observed in 1 hr samples (0.054 ′ 0.035 CA/cell) was higher than basal ones (0.031 ′ 0.026 CA/cell), although this difference was not statistically significant (p= 0.101). For in vitro assay, blood samples were exposed to different concentrations of 1 5 3 Sm-EDTMP, during 1 hr (0.37-1.11 MBq/ml). An increase in the frequency of chromosome aberration per cell as a function of the radioactive concentration was found. The data were adjusted by linear regression model (Y= 3.52 ′ 2.24 x 10 - 2 + 11.15 ′ 3.46 x 10 - 2 X). The frequency of aberration/cell found in vivo was 0.054 and for the same activity in vitro was 0.098, this difference being statistically significant (p= 0.02). This result may be related to blood clearance, osteoblastic activity and individual variability. For a more accurate analysis, the study of more donors is necessary.