Persistent chromosome damage induced by localized radiotherapy for lymphoma.

A fibroblast culture was established from a lymph node biopsy of a patient with non-Hodgkin lymphoma, 9 months after chemotherapy and intensive therapeutic x-irradiation of the area. In contrast with blood and bone marrow, which were chromosomally normal, all cells of the lymph node were chromosomally abnormal, with numerous clones having multiple structural abnormalities. Numerical abnormalities (trisomies and monosomies) were not found. Structural abnormalities included translocations, terminal deletions, and pericentric inversions, with an excess of centromeric breakpoints being the only apparent deviation from a random distribution of breakpoints. None of the rearrangements associated with malignant lymphoma were seen, indicating that the chromosome abnormalities in the lymph stroma were radiation-associated, not disease-associated. These acquired changes may be a cause of additional malignant transformation.