These findings are probably the result of random variation in the large number of response categories. Although the incidence of thyroid C-cell tumor was elevated in a single study, this tumor has never considered been relevant in assessing the carcinogenic potential of any agent. The natural history of the tumor makes it difficult to measure with precision. The single exception is C-cell thyroid tumor, the incidence of which was elevated in only one bioassay, however, this observation has no predictive value for human or animal carcinogens, as noted above. Evaluation of the potential carcinogenicity of 60 Hz linear sinusoidal continuous-wave magnetic fields in Fisher F344 rats.
Vitamin D compounds as potential therapeutics for estrogen-independent breast cancer.