A Novel N-Staging System for Predicting Survival in Patients with Medullary Thyroid Cancer

    • Presentation Speakers / Moderators

    BACKGROUND:
    The status of lymph node metastasis?LNM?is very crucial when evaluating the prognosis of patients with medullary thyroid cancer (MTC). However, only the compartment of LNM was reflected  in the 8th edition (8th) of the  American Joint Committee on Cancer (AJCC) N-staging system. Given that, a more accurate N-staging system is required for MTC. 

    METHODS: 
    Two large cohorts were included in this analysis, consisting of 1374 MTC patients in the Surveillance, Epidemiology, and End Results (SEER) database, and 164 in the Fudan University Shanghai Cancer Center (FUSCC) database. Using metastatic lymph node number (MLNN) and metastatic lymph node ratio (MLNR), a novel N-staging system predicting the survival of MTC was derived, and measured by C-index, compared to the 8th AJCC N-staging system.

    RESULTS: 
    The cutoff values for MLNN were 0 and 12, MLNR were 0.6 (MLNN?12) and 0.75 (MLNN?12). Based on the values of MLNN and MLNR, we proposed a novel N-staging system for MTC: N0, MLNN=0; N1, 1?MLNN?12 and MLNR <0.6; N2, 1?MLNN?12 and MLNR ?0.6, or MLNN?13 and MLNR <0.75; N3, MLNN ?13 and MLNR ?0.75. The C-index was higher for the novel N-staging system than the 8th AJCC staging system (SEER cohort: 0.783; 95% CI, 0.780 to 0.785 vs. 0.756; 95% CI, 0.753 to 0.758; FUSCC cohort: 0.716; 95% CI, 0.712 to 0.720 vs. 0.670; 95% CI, 0.666 to 0.674).

    CONCLUSIONS: The novel N-staging system for MTC proposed in this study provides improvements and may be evaluated for potential adoption in the next edition.

 

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