Clinical implications and perspectives of portal venous circulating tumor cells in pancreatic cancer

Table 2 Clinical impact of portal venous circulating tumor cells on prognosis in patients with pancreatic cancer

Ref.	Patients, N	Cancer stage	Blood source	PoV sample	CTC isolation method	OS, median (95%CI)	PFS, median (95%CI)	Main findings
Bissolati et al[36], 2015	20	Resectable	PoV, PV	Intraoperative	CellSearch	CTCs (-): 23.1 (15.1-31.1) mo, CTCs (+): 26.2 (18.7-33.8) mo	CTCs (-): 19.4 (10.9-27.8) mo, CTCs (+): 18.9 (10.4-27.3) mo	PoV CTC-positive patients had a higher rate of liver metastases than CTC-negative patients.
Tien et al[29], 2016	41	Resectable	PoV, PV	Intraoperative	CMx platform	Not shown	Not shown	Number of CTCs in the PoV was the only significant risk factor of liver metastases within 6 mo after surgery.
Liu et al[23], 2018	29	Locally advanced, metastatic	PoV, PV	Transabdominal US-guided	ClearCell FX system	CTCs < 150/7.5 mL: 19.8 (16.8-25.4) wk, CTCs ≥ 150/7.5 mL: 9.2 (7.8-11.8) wk	Not shown	Higher CTC count in the PoV was associated with liver metastases and shorter OS.
Chapman et al[30], 2020	14	All	PoV, PV	EUS-guided	CellSearch	CTCs < 185/7.5 mL: 40.0 wk, CTCs ≥ 185/7.5 mL: 12.8 wk	CTCs < 185/7.5 mL: 75.4 wk, CTCs ≥ 185/7.5 mL: 29.5 wk	Every 10 CTC increase in the PoV was associated with a 5% and 4% increase in the likelihood of progression and death, respectively.
Padillo-Ruiz et al[38], 2021	35	Resectable	PoV, CV	Intraoperative	IsoFluxTM	CTCs < 185/mL: 24.5 (19.6-29.4) mo, CTCs ≥ 185/mL: 10.0 (7.4-12.5) mo	Not shown	Higher number of CTCs in the PoV was associated with poorly differentiated cancer and shorter OS.
Pan et al[48], 2021	32	Resectable	PoV, PV	Intraoperative	CanPatrolTM	Not shown	Not shown	Mesenchymal CTCs in the PoV ≥ 1/5 mL was a significant risk factor for metastasis, PFS, and OS.
White et al[40], 2021	34	Resectable	PoV, PV	Intraoperative	CellSearch	Not shown	Not shown	Patients with undetectable PoV CTCs showed a higher 18-mo survival rate (100%).
Zhang et al[31], 2021	31	All	PoV, PV	EUS-guided	Cyttel detection kit	Not shown	Not shown	The number of PoV CTCs, especially mesenchymal CTCs, was positively correlated with the advanced stage.
Choi et al[32], 2022	33	All	PoV, PV	Intraoperative	SMART BIOPSYTM	CTCs < 3/7.5 mL: NA, CTCs ≥ 3/7.5 mL: 16.5 mo	CTCs < 3/7.5 mL: 13.4 mo, CTCs ≥ 3/7.5 mL: 7.5 mo	Higher number of PoV CTCs was associated with higher stage, lymph node metastasis, and poorer PFS and OS.
Song et al[37], 2020	32	Resectable	PoV, PV	Intraoperative	Microfabricated Filter	CTCs < 1/10 mL: 40.0 mo, CTCs ≥ 1/10 mL: 17.6 mo	Not shown	CTC count in the PoV was not significantly associated with OS.

CTCs: Circulating tumor cells; PoV: Portal vein; PV: Peripheral vein; OS: Overall survival; PFS: Progression free survival; US: Ultrasound; EUS: Endoscopic ultrasound; NA: Not achieved.