Persistence of micronuclei in lymphocytes of cancer patients after radiotherapy.
To verify the applicability of the micronucleus (MN) yield in peripheral blood lymphocytes (PBLs) as a quantitative biodosimeter for monitoring in vivo ionizing radiation damage, we applied the cytokinesis-blocked micronucleus assay in PBLs of cancer patients treated with partial-body radiotherapy. Dosimetric information on these 13 patients represented a wide range in the number of fractions, cumulative tumor dose, total integral dose, and equivalent total-body absorbed dose. We found in PBLs of these patients that (1) the MN yield increased linearly with the equivalent total-body absorbed dose (r = 0.8, P = 0.002), (2) the distributions of the MN yields deviated significantly from Poisson, and (3) there was a general decline in MN yields with increasing length of follow-up, but with considerable variation between individuals. The average rate of decline was found to be linear and was correlated with the equivalent total-body absorbed dose (r = 0.7, P = 0.007). Further, at 19-75 months of follow-up time, seven patients showed higher MN yields than their respective levels before radiotherapy, indicating the persistence of radiation-induced residual cytogenetic damage. Our findings suggest that the MN yield in human PBLs offers a reliable acute and perhaps chronic biodosimeter for in vivo radiation dose estimation. After the completion of radiotherapy, the persistence of elevated MN yield in PBLs is a reflection of the surviving population of radiation-induced genetically aberrant cells.
Lee
Tung-Kwang
TK
Department of Radiation Oncology, Leo W. Jenkins Cancer Center, Brody School of Medicine at East Carolina University, Greenville, North Carolina 27858, USA. leet@mail.ecu.edu
Allison
Ron R
RR
O'Brien
Kevin F
KF
Naves
James L
JL
Karlsson
Ulf L
UL
Wiley
Albert L
AL
D000368:Aged; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008214:Lymphocytes / Q000473:pathology* / Q000528:radiation effects*; D008297:Male; D048629:Micronuclei, Chromosome-Defective / Q000473:pathology / Q000528:radiation effects*; D008875:Middle Aged; D011878:Radiotherapy / Q000009:adverse effects*; D013997:Time Factors