OTP and carcinoid tumor: In univariable analysis, advanced stage (p = 0.007), as well as atypical carcinoid histology (p < 0.001), Ki-67 index ≥ 5% (p < 0.001), infiltrative growth (p = 0.027), acinar pattern (p = 0.001), and absence of OTP expression (p = 0.001) were unfavorable prognostic factors.