Updated guidelines for the follow-up of thyroid cancer.
Follow-up of thyroid cancer patients is aimed at controlling the adequacy of thyroid hormone treatment and at the early diagnosis of recurrent disease.
Long term thyroxine treatment is given at suppressive doses only in the few patients with persistent or recurrent disease. When cure has been assessed, serum TSH should be maintained in the normal range (around 1 μU/ml).
The absence of disease is first controlled by the total body scan (TBS) performed 3 to 5 days after the post-operative administration of radioiodine. When the TBS is informative and does not show any focus of uptake outside the thyroid bed, a subsequent routine diagnostic TBS is usually not necessary.
Cure is assessed at 912 months with a neck ultrasonography and a serum Tg determination obtained 3 days after rhTSH stimulation (0.9 mg im, on 2 consecutive days). The quality of life of thyroid cancer patients is improved with the use of recombinant human TSH (rhTSH) that avoids hypothyroidism, provides an effective stimulation of any thyroid tissue and does not increase the global cost of follow-up.
Low risk patients with a normal neck US and an undetectable rhTSH stimulated serum Tg are considered cured. This reliable assessment of cure permits reassurance of patients, the subsequent use of replacement doses of thyroxine and the simplicity of the subsequent yearly follow-up with serum TSH and Tg determinations. There is a close relationship between basal and TSH-stimulated serum Tg levels, and the benefits of TSH stimulation may decrease with Tg methods with an improved functional sensitivity. At the present time, there is however no firm evidence that TSH-stimulated Tg determination can be obviated.
When serum Tg is detectable at a low level following TSH stimulation, another TSH stimulation should be performed 1 or 2 years later, and the trend will indicate either irradiated thyroid cells (with decreasing Tg level) or neoplastic cells (with an increasing Tg level).