Influence Of The Updated AJCC/TNM Staging System On Postoperative Assessment For Differentiated Thyroid Cancer And Comparison Of Serum Prolactin Levels Between Patients With Benign And Malignant Thyroid Nodules

Objective:1.To investigate the postoperative mortality risk staging changes of differentiated thyroid cancer resulted from the changes of the AJCC/TNM cancer staging system and explore its clinical significance.2.To compare the serum prolactin levels between patients with benign and malignant thyroid nodules.Methods:1.This study included 2553 patients accepting surgical therapies in Thyroid Surgery from January 2013 to February 2017.Overall,2553 patients were staged according to the 7^th and 8^th editions of the AJCC/TNM cancer staging system respectively.Finally,statistical analysis was performed.2.The serums of 300 patients heading for Thyroid Surgery for surgical therapies from December 2014 to April 2015were collected and stored at-80℃.We selected 100 patients with benign thyroid nodules and 100 patients with malignant thyroid nodules according to gender and age matching principles（the maximum age gap was 5 years）.Then we collected electronic medical records of these patients and performed prolactin measurement.Finally,statistical analysis was performed.Results:1.Compared with the previous staging outcomes,548 patients（21.46%）were downstaged according to the 8^th edition of the staging system.Of these 548patients,438（17.16%）migrated from an advanced stage（III/IV）to stage I/II disease.The difference of the staging outcomes was significant（P<0.001）.Because of the change of age cut off,364 patients（14.26%）were downstaged to stage I.Of these 364patients,318（12.46%）migrated from an advanced stage（III/IV）to having stage I disease.2.Prolactin（m IU/L）levels in patients with benign and malignant thyroid nodules were 117.0（75.5-181.0）and 122.0（86.9-185.0）,respectively.The difference was not significant（P=0.923）.In benign thyroid nodules group,prolactin（mIU/L）levels in patients with tAb+（n=10）and tAb-（n=67）were 89.8（58.4-124.5）and128.0（83.3-197.0）,respectively.The difference was significant（P=0.040）.Conclusion:1.For the changes of the AJCC/TNM cancer staging system,particularly for the change of age cut off,many patients with DTC would be divided to lower stages,and therefore would have less aggressive postoperative management strategies.2.This study had not found significant difference of the serum prolactin levels between patients with benign and malignant thyroid nodules.Nevertheless,studies based on large samples and about prolactin subtypes were needed.