Non-functioning pancreatic neuroendocrine tumors: Surgery or observation?

Table 1 European Neuroendocrine Tumor Society and American Joint Committee on Cancer TNM grading systems for pancreatic tumors[38,39]

	ENETS	AJCC
T Grade (primary tumor)
Tx	Primary tumor is not assessed	Primary tumor is not assessed
T0	No finding of primary tumor	No finding of a primary tumor
Tis		In situ carcinoma
T1	Tumor is limited to the pancreas and < 2 cm	Tumor is limited to the pancreas and ≤ 2 cm
T2	Tumor is limited to the pancreas and 2 to 4 cm	T2 tumor is limited to the pancreas and > 2 cm
T3	Tumor is limited to the pancreas and > 4 cm or with positive duodenum or biliary tract invasion	Tumor has progressed beyond the pancreas but there is no celiac or mesenteric artery involvement
T4	Tumor has invaded the neighboring organs (stomach, spleen, colon, adrenal gland) or walls of the large vessels (celiac artery or superior mesenteric artery)	Tumor shows celiac or superior mesenteric artery involvement
N-lymph node status
Nx	Regional lymph nodes are not assessed	Regional lymph nodes are not assessed
N0	No regional lymph node metastasis	No regional lymph node metastasis
N1	Regional lymph node metastasis is positive	Regional lymph node metastasis is positive
M-distant metastasis
Mx	Distant metastasis is not assessed
M0	No distant metastasis	No distant metastasis
M1	Distant metastasis is positive	Distant metastasis is positive
Stage
0		Tis, N0, M0
I	T1, N0, M0
IA		T1, N0, M0
IB		T2, N0, M0
IIA	T2, N0, M0	T3, N0, M0; T1, N1, M0
IIB	T3, N0, M0	T2, N1, M0; T3,N1,M0
III		T4, Any N, M0
IIIA	T4, N0, M0
IIIB	Any T, N1, M0
IV	Any T, Any N, M1	Any T, Any N, M1

Table 2 Retrospective studies regarding incidental discovery

Ref.	Study period	Patients (n)	Group	Number of patients n (%)	5-yr PFS rates (%)	P value	Median follow-up time (mo)
Cheema et al[18]	1999-2010	143	Incidental	56 (40)	86	0.07	67 (mean)
			Non-incidental	87 (60)	59
Crippa et al[54]	1990-2009	355	Incidental	124 (35)	83	< 0.001	44
			Non-incidental	231 (65)	32
Haynes et al[53]	1997-2009	139	Incidental	109 (82)	82.8	0.27	34.2
			Non-incidental	30 (18)	81.7
Birnbaum et al[55]	1994-2010	108	Incidental	65 (61)	92	0.03	42
			Non-incidental	43 (39)	82

Table 3 Retrospective studies regarding surgery vs observational management

Ref.	Study period	Patients n	Group	Number of patients n (%)	Median follow-up time (mo)	Surgery morbidity rate (%)
Gaujoux et al[56]	2000-2011	46	Observational	38 (83)	> 18	62
			Surgery	8 (17)	27
Lee et al[57]	2000-2011	133	Observational	77 (57)	44 (Mean)	46
			Surgery	56 (43)	52 (Mean)
Rosenberg et al[58]	1999-2014	35	Observational	15 (42)	28	35
			Surgery	20 (58)	34
Sharpe et al[60]	1998-2006	380	Observational	71 (19)	60	N/A
			Surgery	309 (81)	60
Sadot et al[59]	1993-2013	181	Observational	1042 (57)	44	N/A
			Surgery	771 (43)	57

¹Matched group;

²Before cross over; N/A: Not available.