THE RET PTC1 REARRANGEMENT IS A COMMON FEATURE OF CHERNOBYL-ASSOCIATED PAPILLARY THYROID CARCINOMAS FROM BYELARUS/

An increase in the incidence of papillary thyroid cancer has been docu mented in individuals exposed to Chernobyl fallout in 1986. Experiment s using cultured human cells have suggested that radiation can induce the ret/PTC1 rearrangement involving the ret proto-oncogene. To test t he hypothesis that the ret/PTC1 rearrangement is involved in the patho genesis of Chernobyl-associated papillary thyroid carcinomas, we studi ed a panel of 31 cases from Belarus. All individuals lived in fallout- contaminated oblasts (regions) of Belarus at the time of the accident: Gomel (n = 13), Brest (n = 12), Minsk (n = 4), and Grodno (n = 2). Al l were under age 20 at the time of the accident; 20 were born between 1982 and 1986. Individual thyroid radiation doses were estimated at 1. 1 to 110 rem. Patients underwent surgery in Minsk in 1996. Fifteen pat ients had locally advanced disease (stage T4). The majority had region al lymph node involvement (stage N1, n = 27). There were no distant me tastases. Surgical specimens were frozen at -80 degrees C, RNA was ext racted and cDNA prepared. The polymerase chain reaction (PCR) was perf ormed with specific primers for ret/PTC1, and c-ret and GAPDH as contr ols. Controls were positive in all 31 cases. Nine cases yielded a posi tive PCR product for the ret/PTC1 rearrangement (29%). Thus, the ret/P TC1 rearrangement is a feature of some Chernobyl-associated papillary thyroid cancers, and is one possible mechanism involved in the pathoge nesis of these cancers.