Current practice in the therapy of PTC is total thyroidectomy, followed by risk evaluation into low, medium and high risk. This is determine by clinical aspects at the time of surgery. Age, size of the primary, lymph nodes, and distant metastases are the major factors. This is followed by TSH suppression therapy with T4. Early detection of recurrence was attempted by frequent withdrawal from T4 and Total body scans. The patients were reluctant to withdraw with the lingering symptoms of hypothyroidism frequently. In addition, TBS was found to be insensitive with many false negative scan results. Recent data has confirmed that TG can be used to follow the amount of tumor present. The higher the Tg the more tumor is present, if the remnant normal thyroid has been ablated. Serial Tg measurements can detect recurrence, or worsening of the disease.

The use of Thyroglobulin (TG) as a cancer marker has been well documented. It has changed the way we follow patients. The old days of frequent Total Body Scans (TBS), hospitalization for large dose radioiodine therapy for the majority of patients, and withdrawal hypothyroidism every year for the scans are now being replaced by Ultrasound and TG. The new way is to rely on the TG to decide if you need more aggressive therapy. It is used to further determine prognosis after the staging after surgery. That is done by several staging systems. However, the TG on thyroid suppression therapy at one year appears to refine the plan for therapy, and change it to either a more aggressive, or more commonly, a less aggressive approach. A recent study at USC, Kaiser, and Santa Monica Thyroid Center found that there was a linear relationship between the early first year TG on T4 suppression therapy without withdrawal, and the long term ( 9 year ) recurrence rate. An undetectable ( < 1.0 ) TG at one year measured in the TSH suppressed state is prognostic for a low risk recurrent Papillary Thyroid Cancer.

Patients with Tg below 1.0, had a 3.3% risk of recurrence during the 9 year follow up period of the study. 278 patients were followed during this study. There has been an increase in sensitivity in the Tg assay since this study. The new TG assay is now <0.3. This will allow early one year Tg testing to provide prognostic information, and will lead to less need for T4 withdrawal TG testing, and recombinant TSH stimulated TG testing. The group with high Tg >2.0 at one year had 50% recurrence rates, while the low Tg <2.0 patients at one year had only 6.3% recurrence rates. 93% of the low TG group was judged disease free after 5-18 year follow. Persistent and recurrence was 83% in the high TG group with TG> 10.

Tg at one year while taking T4 Suppression therapy to lower TSH.