Is there a correlation between BRAFV600 mutation, sentinel lymph node biopsy, pathological and clinical parameters in papillary thyroid carcinoma?

Background-Aim: The use of preoperative lymphoscintigraphy and intraoperative gamma probe detection to localize the Sentinel Lymph Node (SLN) in PTC in order to evaluate possible association between BRAF mutation, the status of SLN and more aggressive PTC. To evaluate whether BRAF mutations might influence clinical and pathological features in our series of PTC according to the status of the SLN. Methods: We studied 142 patients with PTC (106 females, 36 males—mean age 51.43) who underwent cytological analysis of BRAF mutation status and SLN definition before thyroidectomy. V600E BRAF mutation was investigated by polymerase chain reac- tion (PCR) followed by direct sequencing. We analyzed the potential correlation between BRAF mutation, SLN status, sex, age at diag- nosis, tumour size, stage and cancer multifocality, capsular involvement, peri-thyroid invasion and lymph node metastases. The SLN was detected administering inside the tumour, under Ultrasound Guidance (US), about 68 MBq of 99mTc-NanocollÒ. SLN scan de- tection was performed within 3 h from radiotracer injection with planar and tomographic acquisition (by means of a gamma camera SPECT-CT). The day after scintigraphy, patients underwent thy- roidectomy and SLN removal after intraoperative radioguided localization by a ScintiProbe. At least 6–8 lymph nodes belonging to the same compartment of SLN, were also removed. Then, the samples (thyroid and lymph nodes removed) underwent histopathological examination. The Chi squared test and Odds ratio (OR) were applied for the statistical analysis. Results: 105 patients out of 142 studied showed BRAF mutation, with an high prevalence (*74 %), without a significant correlation between SLN positivity or negativity. In 37 cases we did not found BRAF mutation. The involvement of other lymph nodes in the same compartment of the SLN was not related to BRAF mutation. The analysis of data showed a statistically significant difference between the following parameters: (1) the stage of disease (early or advanced) and SLN positivity or negativity (p \ 0.05) with a negative OR correlation; (2) the peri thyroid structures invasion (or not) and SLN positivity or negativity (p \ 0.01) with a positive OR correlation; (3) the more or less invasion of tumour capsule and SLN positivity or negativity (p \ 0.05) with a positive OR correlation; (4) the incidence of lymph node metastasis and the SLN positivity or negativity (p \ 0.025) with a positive OR correlation. There were no statisti- cally significant difference between BRAF mutation, SLN status, sex, tumour size and tumour multifocality. Conclusion: We found BRAFV600E mutation in 74 % of cases and a negative SLN in 83 % of cases [the 66 % of them were microcarci- nomas (size 5.3 mm ? 1)]. We believe that a small lesion probably does not spread out of the tumour. Data analysis did not show a direct correlation between BRAF mutation and SLN positivity, particularly in an early cancer stage. In the group of patients with peri-thyroidal neoplastic involvement, we found a more likely SLN positivity. Moreover, we found a strong correlation between capsular tumour invasion and SLN positivity. We also showed a more common metastatic lymph node involvement in the group of patients with a positive SLN. In some cases, even if the SLN was negative, we observed an involvement of other lymph nodes belonging to the same compartment of SLN that may be probably due to an abnormal route of radiopharmaceutical lymphatic drainage.