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Tracheal Invasion in Papillary Thyroid Carcinoma

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Question

I would appreciate your advice on the following clinical case. The patient is a 31 year old male who underwent total thyroidectomy and central neck dissection for papillary thyroid cancer, usual type (T3 N1aM0), in 2002. After that he received ablation with radioiodine. Apparently, he was considered with no evidence of disease until 2005, when he underwent a (left) lateral neck surgery for positive nodes. He was given 150 mCi I131, with a negative post dosis scan (the patient was given instruction for low iodine diet). Three months later he came for the first time to our hospital with an ultrasound showing cervical left lymph nodes, which were again positive. There were no signs of invasion in neck and mediastinum MRI, the lungs were normal in CT. A radical neck dissection was performed. No radioiodine was given, since the last post dose scan three months earlier had showed no uptake; at that time thyroglobulin off T4 was 4,8 ng/ml. A few months later, he showed relapse (a node in anterior region of the neck, fine needle aspiration positive for papillary thyroid cancer), which invaded the tracheal wall (from serosa to lumen). A tracheal wall resection (which confirmed invasion from papillary thyroid cancer) with clear margins was performed. He is about to receive 200 mCi I131 with previous rosiglitazone therapy, and lithium. His thyroglobulin antibodies were always negative, and the thyroglobulin off t4 is now 0.9 ng/ml. Would you add external beam radiotherapy? Do you have any suggestions regarding this case? Thank you very much.

In’s Califano, MD
Buenos Aires, Argentina

Response

Your case is certainly a classic problem. The young man has an agressive tumor, with 3 “recurrences” over 3 years, and poor RAIU. At the moment there is no evidence of disease, but in fact it is highly likely that he has some tumor somewhere, possibly in the neck. Radiation has been shown to reduce local recurrence, which would be an argument for using it now in this case. Radiotherapy might prevent further spread, but are no studies to verify this approach. One could argue for radiation now.

On the contrary, the efficacy of radiation to cure is obviously low, although we know it definitely can make papillary tumors shrink. It can be used once. Radiation would probably involve >5000 rads to the soft tissues (“mantle”), with spinal cord sparing, and would quite likely cause considerable scaring and tissue stiffness in 10-20 years.

Right now I would be inclined to wait, check lungs with CAT and abdomen with MRI, and follow neck US and TG. If there is tumor recurrence that can be resected, fine. If he has elevating TG and no evident disease, or disease that can not be resected, and negative imaging, then radiation to the neck would be very supportable.

I offer these thoughts, with the understanding that the data to provide a true answer are, to my knowledge, not available.

Leslie J De Groot, MD