Chernobyl-Related Cancer: Re-Evaluation Needed

Sergei JARGIN

doi:10.5146/tjpath.2010.01021

There has been no clearly demonstrated cancer incidence increase that can be attributed to radiation from Chernobyl accident, except for the thyroid carcinoma in the individuals exposed in childhood and adolescence. The drastic increase of thyroid cancer started 4 years after the accident. The solid/follicular subtype of papillary thyroid carcinoma predominated in the early period after the accident. Histopathological diagnosis of cancer in such cases, if no infiltrative growth is visible, is based mainly on the nuclear criteria of papillary carcinoma. Outdated equipment of histopathological laboratories in early 1990s and insufficient quality of histological sections hindered reliable assessment of the nuclear criteria. Access to foreign professional literature has been limited in the former Soviet Union. Appearance of advanced tumors shortly after the accident can be explained by the screening effect with detection of neglected cancers and by the fact that patients were brought from other regions of the former Soviet Union and registered as Chernobyl-related cases. Further evidence in favor of the overestimation of thyroid cancer incidence after Chernobyl accident is discussed. The concluding point is that immunohistochemical and molecular-genetic tests performed within the scope of international studies were partly based on an inadequately selected material, and that supposedly specific features of radiogenic post-Chernobyl cancers characterize, on average, a later stadium of tumor progression. Therefore, some published data on molecular-genetic and other characteristics of post-Chernobyl malignancies require re-evaluation.