Non-functioning pancreatic neuroendocrine tumors: Surgery or observation?

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