TSH level has been proposed as a thyroid malignancy predictor in nodular thyroid disease. In addition, several clinical studies have reported that higher preoperative serum TSH levels were associated with more advanced stages of differentiated thyroid cancer (DTC) at the time of diagnosis.
Methods: We collected retrospectively preoperative serum TSH from patients diagnosed of papillary thyroid cancer (PTC) who had undergone total thyroidectomy during the period 20012013 in a single tertiary center. We recorded demographic data, nodule number, tumor size and neoplasm features in surgical pathology. Patients with Gravess disease or primary hypothyroidism under treatment prior to surgery were excluded.
Results: A total of 348 patients were included: 92 with incidental microcarcinoma (IMC), 54 with non-IMC (NIMC) and 202 with PTC larger than 1 cm, 105 of them larger than 2 cm. There were no significant differences in TSH levels among IMC and non-incidental cases (2.13 vs 2.53 IMC; P: 0.12). Likewise, TSH concentration was similar in NIMC, PTC >1 and PTC >2 cm (2.85; 2.45 and 2.31 respectively). Neither the presence of multifocality (2.62 vs 2.32), nor extrathyroidal extension (2.78 vs 2.33), nor lymphatic invasion (2.78 vs 2.4) were associated with TSH levels, although higher TSH levels where found when one of those features was present. Aggressive cellular variant or vascular invasion showed lower levels of preoperative TSH (2.17 vs 2.48; P: 0.43). Only the presence of antimicrosomal Abs or diffuse lymphocytic infiltration was significantly associated with higher TSH level. These results did not change when considering exclusively uninodular non-incidental disease in the analysis, although almost all the parameters had lower P value.
Conclusions: Our series suggests that high TSH levels may be involved in the presence of pathological characteristics associated with worse outcome in PTC, but with no statistical significance, unlike to other published series. The only feature actually associated to higher TSH was the presence of autoimmunity.