Aim and backgrounds: Anaplastic carcinoma is the most dangerous form of thyroid cancer. It is a rare and aggressive form of thyroid cancer. It grows very rapidly and does not respond to therapy. In this study the effect of Silibinin on the metabolic activity of a cancerous cell line (8305c) of anaplastic thyroid carcinoma was investigated. Silibinin is a flavonoid that is the major active constituent of the extract of the Milk thistle seeds. Silibinin has been demonstrated to have strong pleiotropic anti-cancer effects against various human carcinoma cells. Materials and Methods: The 8305c cell cultures were treated with Silibinin at 25, 50, 75, and 100 µmol in the MTT plates. After 24 and 48 hours, the metabolic activity of the treated cells was studied using the MTT assay. The MTT assay is a colorimetric method for determination of cell viability and cytotoxicity effects.

Result: The results of this study show that Silibinin has significant cytotoxicity effects on the 8305c cell line. The treatment of the cells with Silibinin at the given concentrations resulted in significant decrease of metabolic activity in a time and dose dependent manner.

Conclusion: From the results obtained by this study It may be concluded that Silibinin significantly reduces the growth of anaplastic thyroid cancerous cells. More investigation is underway to reveal the mechanism by which Silibinin prevents cancer metastasis.