Diethylstilbestrol-exposed monozygotic twins discordant for cervicovaginal clear cell adenocarcinoma.

Monozygotic, 17-year-old, female twins exposed to diethylstilbestrol (DES) in utero and discordant for cervicovaginal clear cell adenocarcinoma are reported. Benign teratologic changes were present in both. The twin with cancer was treated by extensive operation and postoperative irradiation. No tumor has appeared in either twin in the 4 years subsequent to therapy. Discordance for cervicovaginal clear cell adenocarcinoma in this situation suggests that factors other than embryonic exposure to DES, extrauterine in location and nongenetic in character, were operative in tumorigenesis. The twins were compared in regard to lifetime radiation exposure and evidence of previous viral disease. The only substantial difference was an elevated titer of antibody in the twin with cancer to the capsid antigen of the Epstein-Barr virus, a herpesvirus with oncogenic capability.