Is a radioactive iodine uptake test needed to rule out thyroid cancer?

No. Radioactive iodine test is of little or no value in the evaluation for thyroid cancer. Ultrasound and biopsy are much more important.
RAI scan and cancer. RAI scans USED to be used to diagnose dancer of the thyroid. This is arcane and has been supplanted by ultrasound guided thyroid needle biopsy. The only exception would by a thyroid nodule in a hyperthyroid patient.
No. Radioactive iodine scans used to be used for that purpose, but are not accurate enough. Ultrasound followed by fine needle aspiration biopsy is the best test.