Thymic neuroendocrine tumors (TNET) are rare primary epithelial neoplasms of the thymus. This study aimed to determine clinically relevant parameters for their classification and for therapeutic decisions. We performed a comprehensive histological, clinical, and genetic study of 73 TNET cases (13 thymic typical carcinoids [TTC], 40 thymic atypical carcinoids [TAC], and 20 high-grade neuroendocrine carcinomas [HGNEC] of the thymus), contributed by multiple institutions. The mean number of chromosomal imbalances per tumor was 0.8 in TTC (31% aberrant cases) versus 1.1 in TAC (44% aberrant cases) versus 4.7 in HGNEC (75% aberrant cases). Gains of 8q24 (MYC gene locus) were the most frequent alteration and one of the overlapping features between carcinoids and HGNEC. The 5-year survival rates for TTC, TAC, and HGNEC were 100, 60, and 30%. The 10-year survival rates for TTC and TAC were 50 and 30% (P=0.002). Predictive mitotic cut-off values for TTC versus TAC were 2.5 per 10 high-power fields (HPF; indicating a higher death rate, P=0.062) and 15 per 10 HPF (indicating higher risk of recurrence, P=0.036) for separating HGNEC from TAC. We conclude that the current histopathologic classifications of TNET reflect tumor biology and provide important information for therapeutic management.
ASJC Scopus subject areas
- Cancer Research