Two isoforms of thyroid receptor alpha (THRα1 and THRα2) have been found to be associated with the growth of cancer. Use of inhibitors of THRα1 (Formula I) and/or agonists of THRα2 (Formula II) in the treatment of such cancers is disclosed. Treatment of other disorders associated with such receptors is also contemplated, as is the use of diagnostic methods for predicting therapeutic outcomes based on the levels of expression of THRα1 and THRaα2 in a tissue sample.