Table 2.

Circulating neuroendocrine-specific mRNAs detected in PB of SCLC patients.

Gene Symbol	Molecular Assay	Cohort Size (N)	% Positive Patients	Results	Refs
SSTR2a	RT-qPCR	14	93% (13/14)	The detection in PB was associated to SCLC	[22]
				The positivity in PB was correlated to OctreoScan captation	[22]
SSTR5	RT-qPCR	14	8/14 (57%)	The detection in PB was associated to SCLC	[22]
				The positivity in PB was correlated to OctreoScan captation	[22]
HuB (ELAVL2)	RT-qPCR	25	13/25 (52%)	The detection in PB was associated to SCLC	[34]
				The HuB/HuD positivity in PB was observed in LD SCLC stage	[34]
HuC (ELAVL3)	RT-qPCR	25	4/25 (16%)	The detection in PB was associated to SCLC	[34]
HuD (ELAVL4)	RT-qPCR	25	6/25 (24%)	The detection in PB was associated to SCLC	[34]
				The HuD/HuB positivity in PB was observed in LD SCLC stage	[34]
SYP	microfluidic Parsortix/RT-qPCR	51	11/51 (21.6%)	The detection in PB was associated to SCLC	[48]
				The SYP/CHGA positivity was associated to shorter OS	[48]
CHGA	microfluidic Parsortix/RT-qPCR	51	6/51 (12%)	The detection in PB was associated to SCLC	[48]
				The CHGA/SYP positivity associated to shorter OS	[48]
DLL3	microfluidic Parsortix/RT-qPCR	51	4/51 (7.8%)	The detection in PB was associated to SCLC	[48]
				The positivity in PB was associated to shorter OS	[48]
ProGRP	RT-qPCR	32	16/32 (50%)	The positivity in PB was associated to SCLC condition	[53]
	RT-qPCR	122	nr	The detection in PB was associated to SCLC	[54]
				The positivity in PB was correlated to ProGRP serum positivity	[54]
				The positivity in PB was correlated to tumor size, disease stage and distant metastasis	[54]
SCG3	RT-qPCR	67	24/67 (36%)	The detection in PB was associated to SCLC	[67]
				The positivity in PB was associated to poor survival and worse treatment response.	[67]
SCG3	RT-qPCR	26	12/26 (46%)	The detection in PB was associated to SCLC	present work