Wednesday, January 14, 2009

PEI in Thyroid Cancer Recurrence

Thyroid Cancer Conference:

Case: Patient with stable thyroid cancer disease with detectable Tg and Tg-Ab with previous history of thyroidectomy present with neck pain. TSH was 33 and Tg 30. CT evaluation and ultrasound show residual thyroid tissue. With TSH suppression, the Tg dropped to a low level again. The Tg-ab had been stable throughout without any rise.

Question of the options:
1. is this recurrence?
2. options: RAI, thyroid surgery, just followup, or PEI.

Dangers of PEI
1. nerve damage. The laryngeal nerve is very delicate. alcohol can cause permanent damage to this nerve.
2. A large amount of alcohol is needed to treat a large lesion
3. Not currative.

In terms of recurrence, Tg-ab may be a better marker of disease than Tg in this case?

On CT, the thyroid tissue will light up like bone.


  1. I think that I may have made a similar point before, but in a seperate e-mail: I have seen a number of patients s/p thyroidectomy with low suppressed Tg levels (i.e. 1-4) and with u/s evidence of residual tissue. I have observed with repeat suppressed Tg levels in 3 months, and found that the Tg was the same to lower. Also I have one patient with detectable Ab levels and u/s evidence of residual tissue for which the Ab levels have been very slowly decreasing over the past 2 years (i.e. 700->500->400->200s).

    My conclusion has been that these patients had incomplete thyroidectomies and have residual thyroid tissue (in fact probably 3/5 initially had a lobectomy for what was thought to be benign disease and then had a "completion" thyroidectomy).

    This is what I think is going on in the above patient as well. I believe that the Tg of 30 was due to "stimulated" thyroid tissue. I don't really know what the antibody response is to stimulation, because I don't do it, however I would expect that as antibody levels go, the changes are slow and might account for the lack of change.

    I am assuming that the TgAb levels have been detectable as well in the past? If this is the case then my opinion would be to observe and repeat Tg and TgAb in 4 months. I do think that the TgAb would be a better marker in this case, but for piece of mind I would also follow with imaging to look for any increase in size of the residual tissue. If there is no change in the residual tissue, then I would only follow by Tg antibody. Any significant increase in the TgAb levels would be my cue to treat.

  2. That's a great comment Mike but what about RAI ablation in this case. Luckily this issue did not come up in the boards but across the country I think most endocrinologists would give this patient RAI. I've been to a few conferences here at the Mayo and tend to agree with their approach of calculating the MACIS score and if its greater than 6--> RAI ablation is given. Perhaps Andy could calculate that for us or give more details of the case. Great case and perfect for the RAI ablation debate. Let me know what you guys think.

  3. Thanks Manpreet. I knew I was leaving something important out:

    I like to use the MACIS score as well and get it for each patient. The patients that I mentioned ALL had MACIS scores of < 6 and elected to NOT have radioactive iodine. That's why I felt so certain that they had remnant thyroid tissue.

    In the case above it may be remnant thyroid or remnant thyroid ca. I assumed that this patient did not get ablation, in which case I would feel more comfortable observing.


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