Chernobyl Cancer Studies with Overseas Control: High Grade vs. Late Detection.

This is an addition to the review published in the Turkish Journal of Pathology (1), commenting on the series of studies (2-7), in particular, the last one making a comparison of clear-cell renal carcinoma (RC) tissue specimens from Ukraine with those from Colombia and Spain (7). Thyroid cancer (TC) is discussed by analogy. RCs from Ukraine tended to be higher-grade than those from Spain and Colombia (2-7); among others, they displayed a sarcomatoid i.e. poorly differentiated pattern more frequently: 62 from 236 (26.3%) of Ukrainian vs. 11 from 112 (9.8%) of Spanish cases (p<0.001) (2). The statistically significant difference was confirmed in the later work (4). In the recent study, the microvessel density in RC tissue from patients residing both in “highly” and “low contaminated areas of Ukraine” (7) was higher than that in RC from Spain and Colombia (p<0.01). The difference between the two Ukrainian groups was statistically insignificant. The increased angiogenesis was associated with a higher expression of VEGF (7). It was assumed that the exposure to ionizing radiation leads to an increase in the microvessel density, which in turn is associated with a higher grade of RC (6,7). In this connection, the following citations should be commented: “The dramatic increase of aggressivity and proliferative activity” was found in RC from Ukraine, while “the majority of the high grade tumors occurred in the Ukrainian (rather than in the Spanish) groups” (2). These differences can be explained by the earlier cancer detection on average in Spain and discovery by the screening of advanced cases in Ukraine (8).