High Dose vs Low Dose I 131 +/- rhTSH for Differentiated Thyroid Cancer

DISEASE CHARACTERISTICS: * Histologically confirmed differentiated thyroid cancer * T1-T3, Nx, N0, N1, M0 disease * Has undergone one- or two-stage total thyroidectomy with or without lymph node dissection * All known tumor resected (R0) * Requires radioiodine remnant ablation * Does not require mandatory recombinant thyroid-stimulating hormone * No Hurthle cell carcinoma or aggressive variants, including any of the following: * Tall cell, insular, poorly differentiated disease with diffuse sclerosing * Anaplastic or medullary carcinoma PATIENT CHARACTERISTICS: * WHO performance status 0-2 * No severe comorbid conditions including, but not limited to, any of the following: * Unstable angina * Recent heart attack or stroke * Severe labile hypertension * Dementia * Concurrent dialysis * Tracheostomy needing care * Learning difficulties * Inability to comply with radiation protection issues * Requirement for frequent nursing or medical supervision that puts staff at risk for unacceptable radiation exposure * No other cancers except basal cell skin cancer or carcinoma in situ of the cervix * Not pregnant or nursing * Negative pregnancy test * Fertile female patients must use effective contraception during and for 6 months after radioiodine remnant ablation * Fertile male patients must use effective contraception during and for 4 months after radioiodine remnant ablation PRIOR CONCURRENT THERAPY: * See Disease Characteristics * More than 3 mon…