We found IQGAP1 copy number (CN) gain ≥ 3 in 1 of 30 (3%), 24 of 74 (32%), 44 of 107 (41%), 8 of 16 (50%), and 27 of 41 (66%) of benign thyroid tumor, follicular variant papillary thyroid cancer (FVPTC), follicular thyroid cancer (FTC), tall cell papillary thyroid cancer (PTC), and anaplastic thyroid cancer, respectively, in the increasing order of invasiveness of these tumors.