Sentinel Lymph Node Biopsy In Papillary Thyroid Carcinoma

?Background?Papillary thyroid carcinoma (PTC) is the most common cancer in head and neck region and the incidence increasing by 6.2%per year. Surgical treatment is the effective therapy for patients with PTC. PTC has an intense tendency to metastasize to local lymph nodes. There is a very high incidence of clinical and microscopic incidence of lymph node metastasis in PTC. ranging from 39.5%to 80%of patients. It remains controversial weather prophylactic lymph node dissection is benefit for patients with PTC because lack of reliable and minimal invasive methods to assess neck lymph nodes status. Sentinel lymph node biopsy (SLNB) has become the standard method in breast cancer to assess axillary lymph node status for about 6 years. Enlightened by the progress in breast cancer, various clinical trials using SLNB as a method to assess neck lymph nodes status are on onging abroad.[Objectives! To investigate the reliability.feasibility and the false negative cause of sentinel lymph node biopsy(SLNB) of papillary thyroid carcinoma using combination of lymphoscintigraphy, the gamma probe and methylene blue staining techniques. We also try to study the methods of reducing the false negative rate.[Methods] Fifty-one patients with thyroid papillary carcinoma were entered in the study between August 2007 and September 2010. All cases were without clinical evidence of cervical lymph node involvement. The 99mTc-dextran of 74 MBq(2mCi) was injected intratumoral under ultrasound guidance about 1.5 h to 8h before operation. Methylene blue was injected around the tumor during operation. Preoperative lymphoscintigraphy, intra-operative hand-held gamma probe detecting and methylene blue staining techniques were used to detect the sentinel lymph node(SLN). Immediately after excision, all sentinel nodes were submitted fresh for frozen section analysis, and the results were compared with specimen of routine selective neck dissection. All 55 SLNs of 18 cases which were negative by routine HE examination were serially sectioned at a 50?m interval and stained by both HE and immunohistochemistry for detecting micrometatasis.[Results] The SLNs were identified in all cases with the combination techniques. The SLN identification rates were 90.2%and 96.1%with methylene blue staining and lymphoscintigraphy plus probe scanning respectively. Thirty-nine patients out of 51 had lymph node metastasis. The occult lymph node metastasis rate was 76.5%. Metastases in SLNs were revealed in 31 cases.33 cases and 38 cases by frozen-section histology, routine HE examination and step sectioning plus immunohistochemically stains for cytokeratins (CK7) and thyroid transcription factor-1(TTF-1) respectively. The overall accuracy of the SLN biopsy was 82.3%.88.2%and 98%and the false negative rate was 20.5%,15.4%and 2.6%respectively. There were 55 SLNs which detected by step sectioning plus immunohistochemically stains and lymph node micrometastasis were revealed in 5 SLNs.Five cases out of 18 had lymph node micrometastasis. The false negative rate was reduced to 2.6%by step sectioning plus immunohistochemically stains.?Conclusions?The results seem the SLN biopsy technique is a feasible and valuable method for detecting cervical lymph node metastasis and is helpful to decide performing neck dissection in patients with clinical negative papillary thyroid carcinoma. Step sectioning histology plus immunohistochemically stains can reduce the false negative rate obviously.