What is the role of drug treatment in Differentiated Cancer of the Thyroid?

Giving patients large doses of thyroxine causes thyroid cells to atrophy. This is because the thyroid is dependent on TSH. Many patients will need thyroid replacement anyway. For patients in low risk groups it is only necessary to keep the TSH within the lower end of the range.However in high risk patients life-long suppression of serumTSH to below normal(<0.1mlU/L) is mandatory.Mr Lynn does not agree with the British Thyroid Association (BTA)guidelines of 2007 which suggest starting patientsempirically on 175 or 200 micrograms of thyroxine daily. Mr Lynn thinks this a potentially dangerous policy.The reason for his view is that it is obvious that the dose of thyroxine needed to supress the TSH will depend on body weight.A small frail lady will be overtreated by the BTA Guidelines and be at risk of atrial fibrillation while thelarge patient will be undertreated. One of the lessons of the General Medical Council's inquiry in 2007into euthyroid patients being given thyroxine was their reluctance to stopor reduce their dose because of a feel good factor.For many years Mr Lynn's policy has been to adjust the dose by weightstarting the patienton 2.5 micrograms per kilogram per day taken before breakfast.The calculated dose of thyroxine is rounded up to the nearest 25 micrograms. Thus a60 kilogram women would be on 150 micrograms of thyroxinea day. At 6 weeks the TSH is checked and the dose of thyroxine adjusted up or down as necessary.In elderlypost-menopausal women this policy avoids problems with thyroxine induced accelerated osteoporosis and the increase risk of cardiac disese.It is only in men that the increase risk of thyrotoxic osteoporosis increases the risk of hip fracture.

There is a very limited role for chemotherapy in the treatment of papillary cancer of the thyroid.The Royal Marsden Hospital Londonstarted in 2007 toconduct a trial usingSorafenib which is known to be effective in renal cell carcinoma in patients who were not responsive to radioactive iodine.Sorafenib is a multi-targeted kinase inhibitor.Kinases regulate howcells work and grow,they send signals within the cell that tell it to divide andmake new cells.Sorafenib blocks these signals andinhibits cancer growth.In oneof our patients the early results are encouraging,the thyroglobulin has fallen and the disease has clinically regressed.We will know more when the trial is completed.