Combination Radiotherapy and Radiopharmaceutical Therapy Treatment Planning for Thyroid Cancer

The study goal is to evaluate combined radioactive iodine (RAI, 131-I) and external beam radiotherapy (XRT) to optimize the radiation dose delivered to treat well-differentiated thyroid cancers (DTC) with iodine-avid metastases, hypothesizing that this combination approach is safe and enables delivery of higher local radiation doses than could otherwise be safely delivered with either radiotherapeutic modality alone. This is an open-labeled, phase 1 clinical trial design that will enroll study subjects with recurrent DTC that is not completely resectable with macroscopic invasion of tumor into cervical soft tissues and/or non-resectable distant metastases. Study subjects will have a sub-therapeutic level of lesional RAI uptake demonstrated in either a pre-treatment diagnostic scan or a previous post-treatment radioiodine scan, making it unlikely that the patient would fully benefit from RAI therapy alone. The primary objective is evaluate safety as defined by the incidence of maximum grade 3 or greater NCI CTCAE grade toxicity observed during the treatment period and for the first 30 days following completion of radiotherapy. Additional secondary endpoints will evaluate efficacy at 6 months and feasibility of this combination to deliver a minimum cumulative dose of 80 Gy (66 Gy, Equivalent dose in 2Gy fractions (EQD2); 2 Gy per fraction) to the index tumors (up to 3 in each study subject) selected prior to treatment initiation. The investigators plan to enroll 48 subjects at an accrual rate of 1 subject per month over a study duration of 4 years.