Sentinel lymph node biopsy in papillary thyroid cancer: Accuracy and application in clinical practice

Abstract

Introduction: The presence of lymph nodes metastasis in papillary thyroid cancer (PTC) modifies the type of surgical resection as well as the indication of the treatment with I¹³¹ in the postoperative period. This therapeutic approach is based on the results of the diagnostic tests, like the cervical ultrasonography. Currently other methods of diagnostic are tested as selective sentinel lymph node biopsy (SLNB). It can complement to the ultrasound results. The aim was to validate the SLNB for use in the diagnosis of lymph node metastasis by papillary thyroid cancer.

Methods: Observational prospective cohort study of 55 patients who underwent PTC without suspicion of lymph node involvement clinical or radiological, since February 2012 through February 2015, with a follow-up between 6 and 8 years. It was used ⁹⁹Tc with intratumoral nanocoloid and a portable tube of the gamma camera for the detection of the sentinel node (SN).

Variables: age, gender, histological, analytical and preoperative and postoperative staging. The sensitivity, specificity and predictive values of technique was calculated. The validation was determined by calculating the detectability and the false negative results of the test.

Results: 53 of the 55 patients (96,36%) there was the SN detection. The FN were 4 patients (7,5%). Of the rest, after applying the SLNB, 24 (48,9%) were kept as N0, 14 (28,5%) became N1a and 11 (22,4%) were classified as N1b. The differences observed in the study were significant (P < ,05). The sensitivity was 86,21%, the specificity of 100%, the PPV was 100% and the NPV of 85.71%. The diagnostic accuracy of 92,45%.

Conclusion: The SLNB is a valid technique for use in patients suffering from papillary thyroid cancer with a high diagnostic accuracy.

Keywords: Biopsia centinela; Ganglio linfático; Lymph node; Neoplasia de tiroides; Sentinel lymph biopsy; Thyroid neoplasm.