**3.1 Chemotherapeutic agents**

Cytotoxic chemotherapy has limited role in treatment of thyroid cancer, as most trials using cytotoxic chemotherapies in thyroid cancer have shown disappointing efficacy. FDA approved doxorubicin for the treatment of thyroid cancer in 1974. Chemotherapy regimens with doxorubicin have shown 30–45% partial response in differentiated thyroid cancers [14, 15]. The combination of cisplatin and doxorubicin did not result in any additional improvement in overall response compared to doxorubicin alone [16]. Various other combination chemotherapy regimens also have not yielded any encouraging results so far [17, 18]. Chemotherapy is generally not recommended for patients with differentiated thyroid cancers in view of poor response rates, short duration of response, and toxic effects of chemotherapy [19]. Similar to DTC, chemotherapy has a limited role in the treatment of persistent or recurrent MTC due to the poor response rates (10–15% partial response) [20]. Combination chemotherapy regimens based on dacarbazine and doxorubicin have been tried in MTC, but with limited results [21]. In anaplastic thyroid cancers, chemotherapy in addition to surgery and radiation showed longer median survival rates for stage IVA and IVC ATC patients in a US national cancer registry study [22]. Few other studies have also demonstrated the utility of neoadjuvant chemotherapy in patients with stage IVA and IVB tumors allowing them to undergo successful resection [23]. In advanced cases, doxorubicin, taxanes (paclitaxel or docetaxel) and platins (cisplatin or carboplatin) have demonstrated activity with response rates ranging from 15 to 25% [24, 25].
