Detecting Recurrence Following Lobectomy for Thyroid Cancer: Role of Thyroglobulin and Thyroglobulin Antibodies

BACKGROUND: The use of thyroglobulin (Tg) and thyroglobulin antibodies (TgAb) for detecting disease recurrence is well validated following total thyroidectomy and radioiodine ablation. However, limited data are available for patients treated with thyroid lobectomy. METHODS: Patients who had lobectomy for papillary thyroid cancer followed for >1 year, with sufficient data on Tg and TgAb, including subgroup analysis for Hashimoto's thyroiditis and contralateral nodules. RESULTS: One-hundred sixty-seven patients met the inclusion criteria. Average tumor size was 9.5 ± 6 mm. Following lobectomy, Tg was 12.1 ± 14.8 ng/mL. Of 52 patients with Hashimoto's thyroiditis, 38% had positive TgAb with titers of 438 ± 528 IU/mL, and in patients without TgAb the mean Tg level was 14.7 ± 19.0 ng/mL. In 34 patients with contralateral nodules ≥1 cm, Tg was 15.3 ± 17 ng/mL. During the first 2 years of follow-up, Tg declined ≥1 ng/mL in 42% of patients (by 5.1 ± 3.7 ng/mL), remained stable in 22%, and increased in 36% (by 4.9 ± 5.7 ng/mL). During a mean follow-up of 6.5 years (78 ± 43.5 months), 18 patients had completion thyroidectomy and 12 were diagnosed with contralateral cancer (n = 8) or lymph node metastases (n = 4). In patients with recurrence followed for >2 years, there was a rise in Tg in 3 cases, Tg was stable in 2 cases, and in 1 TgAb decreased from 1534 to 276 IU/mL despite metastatic lymph nodes. Basal Tg and Tg dynamics did not predict disease recurrence. CONCLUSIONS: Serum thyroglobulin used independently is of limited value for predicting or detecting disease recurrence following thyroid lobectomy. Other potential roles of Tg, such as detecting distant metastases following lobectomy, should be further studied.