Clinical Significance Of Thyrotropin In Differentiated Thyroid Cancer

Background and Purpose:Thyroid nodular disease is a very common disease in clinical practice, especially in recent years. Although most of those were benign, the prevalence of thyroid cancer is rising, in which papillary carcinoma and follicular carcinoma having the highest incidence. Early diagnosis and timely effective treatment, the 5-year survival is up to 95.8%, so how to earlier distinguish between malignant and benign thyroid nodules is important for patients in treatment options and the prognosis. Thyroid stimulating hormone (thyrotropin, TSH) is a natural thyroid tissue growth factor, which is associated with the growth of thyroid cancer. Application of levothyroxine in patients with thyroid cancer after surgery can inhibited TSH secretion to reduce tumor recurrence. There lacked large scale investigation on this topic. This paper aimed at a close detection of the relationship between DTC and TSH and exploring a binary category logistic regression model, so as to find a simple and effective identification method to distinguish malignant and benign thyroid nodules through reviewing the preoperative thyroid function parameters and general clinical characteristics of 956 patients with thyroid nodules and receiving surgical treatment in Shandong University Qilu Hospital.Research methods:Select patients with thyroid nodules having surgery in Shandong University Qilu Hospital from Jan.2002 to Mar.2010. Exclude those who had received treatment before the surgery which would affect the preoperative THS level, including taking levothyroxine or hormone, receiving radioactive iodine treatment and having received thyroid surgery before, and those whose pathological results were medullary carcinoma, undifferentiated carcinoma or lymphoma. Collect the information of the remaining patients, including general information, thyroid examination, thyroid function test within one week before surgery [including:three free triiodothyronine (FT3), free triiodothyronine four (FT4), thyroid stimulating hormone (TSH)] and postoperative pathological results. According to the pathology, we divided the cases into benign group and differentiated thyroid cancer group. Use the SPSS 16.0 statistical software to analyze the clinical data. Binary Logistic regression model was used to predict the malignant and benign thyroid nodules.Result:1. From January 2002 to March 2010, a total of 1253 cases of patients with thyroid nodules were admitted to the hospital and received operation.956 cases met the study criteria, of which 738 cases were benign nodules, and 218 patients were DTC.2. According to the statistics, there was no significant difference in the gender composition between two groups (P=0.183).The average age in the DTC group was (46±13.3) years, which was lower than that of (49±12.7) years in benign group (P=0.001).DTC group had the average nodule diameter (1.83±1.31) cm, which was smaller than the benign group (2.50±1.27) cm (P<0.001).152 cases of 218 DTC patients with single nodule (69.7%), compared to 445cases of 738 patients of benign nodules with single nodule (58.9%), there were significant differences (P=0.013). There were 104 cases (47.7%) in DTC group with microcalcification, significantly higher than the number of 138 (18.7%) in benign group. The difference was statistically significant (P<0.001).3. In DTC group, the median TSH was 2.10 mIU/L, significantly higher than that in benign group 1.48 mIU/L (P<0.001). The mean FT3 in the DTC group was (2.84±0.70) pg/ml and (2.94±0.72) pg/ml in the benign group. No significant difference between the two groups (P=0.252).The mean FT4 in the DTC group was (16.15±3.85) pmol/ml, and (16.68±3.07) pmol /ml in the benign group. No significant difference between the two groups (P=0.206). 4. In the DTC group, the higher the tumor stage, the higher the average level of TSH; patients with lymph node metastasis have significantly higher average level of TSH than those without lymph node metastasis; patients with obvious calcification had significantly higher average level of TSH than those without calcification. The differences were all statistically significant.5. Select 0.27 mIU/L,1.40 mIU/L,2.30 mIU/L,4.20 mIU/L as the cutoff value, all the patients were divided into 5 consecutive stages according to their serum TSH levels. With the increasing of TSH rank, the risk of DTC gradually increased.6. Logistic regression analysis showed thatmen, younger than 40 years old, microcalcification, smaller nodular size and TSH level> 2.30mIU/L were at increased risk for DTC for those with thyroid nodules.Conclusion:This study showed that even within the normal range TSH, along with elevated TSH level the incidence of thyroid cancer had increased. In DTC patients, the higher TSH level was associated with advanced thyroid cancer stage and lymph node metastasis of malignancy. So it was supposed that higher TSH may stimulate the occurrence and development of differentiated thyroid cancer. The clinical significance of this study is that we can combine the general clinical features, thyroid examination and thyroid function tests to initially diagnosis of patients with thyroid nodules. And then adopt further examination or treatment to those suspicious patients with malignancy, such as fine-needle aspiration or surgery. If the report of fine-needle aspiration is thyroid cancer or intraoperative examination is DTC accompanied by a high TSH level, the patients should gain suspicion to have advanced tumor stage or exist lymph micrometastases, so careful check of neck lymph nodes and tissues around thyroid. It may be necessary to expand surgery scope and strive complete resection the thyroid cancer to reduce the risk of tumor recurrence. If the fine-needle aspiration did not find the cancer cell, closely following up or re-biopsy may be needed for those with higher TSH levels.