[Clinical significance of lymphatic metastasis between sternocleidomastoid and sternohyoid muscle in papillary thyroid cancer].

Objective: To explore the clinical significance of metastasis of lymph nodes between sternocleidomastoid and sternohyoid muscle (LNSS) in papillary thyroid cancer (PTC). Methods: A total of 175 patients with PTC who underwent thyroidectomy with LNSS dissection were retrospectively analyzed. Univariate and multivariate Logistic regression analyses were used to determine the independent risk factors for LNSS metastasis in PTC. Results: The rate of detectable LNSS was 70.9% (124/175) and metastasis rate was 7.4% (13/175). Of 13 cases with LNSS metastasis, 10 with the coexistence of cervical lymph node metastasis. Univariate Logistic regression analysis showed that multiple focal cancer, tumor located in the lower pole of thyroid, belt-shaped muscle invasion, lateral cervical lymph node metastasis, cN+ , the number of cervical lymph nodes with metastasis and the number of lymph nodes with metastasis in level Ⅳwere the risk factors for LNSS metastasis (P<0.05). Multivariate Logistic regression analysis suggested that tumor located in the lower pole of thyroid and the number of cervical lymph nodes with metastasis >6 were the independent risk factors for LNSS metastasis (P<0.05). Given the number of cervical lymph nodes with metastasis as a predictor for the LNSS metastasis, the sensitivity was 92.3%, the specificity was 66.7% and the accuracy rate was 68.6%. Conclusions: LNSS metastasis is commom in PTC, with a metastasis rate of 7.4%. PTC in the lower pole of thyroid and the number of cervical lymph nodes with metastasis > 6 are independent risks for LNSS metastasis.