γ-H2AX foci in peripheral blood lymphocytes to quantify radiation-induced DNA damage after 177Lu-DOTA-octreotate peptide receptor radionuclide therapy.

The paper by Denoyer et al. in the current issue of The Journal of Nuclear Medicine (1) explores the possibility of quantifying radiation-induced DNA damage after internal treatment with 177Lu-DOTA-octreotate (LuTate) peptide receptor radionuclide therapy for metastatic or inoperable neuroendocrine tumors. Radiation-induced DNA damage was quantified by analyzing the kinetics of phosphorylated histone variant H2AX (g‐H2AX) foci in peripheral blood lymphocytes. The results showed a significant correlation between peak-foci number and absorbed dose to tumor and bone marrow. The authors suggest that as a next step, studies are needed in two directions: first with respect to acute toxicity, that is, investigating the high dose end of the DNA damage; and then with respect to the secondary malignancy resulting when misrepaired damage leads to radiation-induced mutations. Radiation produces its main damage in the nucleus of cells. Clusters of ionization in the DNA result in the damage typical of