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Possible transient adaptive response to mitomycin C in peripheral lymphocytes from thyroid cancer patients after iodine‐131 therapy
Author(s) -
Monteiro Gil Octávia,
Oliveira Nuno Guerreiro,
Rodrigues António Sebastião,
Laires António,
Ferreira Teresa Cruz,
Limbert Edward,
Rueff José
Publication year - 2002
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.10768
Subject(s) - mitomycin c , medicine , micronucleus test , lymphocyte , thyroid cancer , population , subclinical infection , bone marrow , thyroid , cancer , endocrinology , gastroenterology , immunology , toxicity , surgery , environmental health
Our study attempted to assess the possible induction and persistence of an adaptive response in lymphocytes of thyroidectomized thyroid cancer patients treated with 131 I (2,590 MBq, corresponding to whole body doses in the range of 200–300 mGy), to a testing dose of mitomycin C (MMC) in vitro . The cytogenetic endpoint studied was the induction of micronuclei in cytokinesis‐blocked peripheral blood lymphocytes, immediately before treatment and 1, 6 and 24 months after therapy. One month after therapy, induction of micronucleated cytokinesis‐blocked lymphocytes (‰) by MMC was lower (34.6 ± 7.7) than before therapy (52.1 ± 5.0). In 7 of 11 patients this reduction was significant. However, at 6 months, induction of micronuclei was markedly higher (133.1 ± 13.6). This significant increase was observed regardless of the decrease at 1 month. At 24 months, the frequency of micronucleated cells decreased (84.8 ± 5.5), but remained higher than before treatment. The results obtained 1 month after therapy could reflect adaptation due to radiation, or a higher rate of early apoptosis or cell death, with bone marrow suppression, visible as a lower response in vitro towards MMC. At 6 months, recovery of the lymphocyte population may occur, and higher responses to MMC in vitro could reflect higher chromosomal instability in the previously irradiated stem cells with a concomitant disappearance of adaptation, whereas at 24 months the results show a tendency to return to pretherapy values. © 2002 Wiley‐Liss, Inc.