Proliferation, expressed both by Ki-67 index and by grade, was identified as the only independent risk factor: HR (per 2-fold increase in Ki-67 index) 1.3, 95%-CI: 1.1–1.6, p = 0.008, HR (NET G1 vs. NET G2) 2.8, 95%-CI: 1.1–7.2, p = 0.031, and HR (NET G1 vs. NEC) 11.1, 95%-CI: 2.0–60.9, p = 0.005 (Table 3). Here, MKI67 is linked to neuroendocrine carcinoma.