Table 2.

Advantages and disadvantages of two different routes for delivering oncolytic viruses.

	Intratumoral delivery	Intravenous delivery	Intraperitoneal administration	Intrathecal administration	Subcutaneous administration
Advantages	High concentration of oncolytic virus at target tissue to observe a definite effect (39–41)	Good choice when injecting oncolytic virus directly into tumors is challenging (26, 42, 43, 54, 55, 58, 59)	Absorbed faster than subcutaneous injection (65)	An ideal choice for CNS tumors (68)	Easy to operate (65)
	Enables researchers to control the precise concentration of the oncolytic virus in tumor sites (26, 42, 43)	Convenient and rapid for researchers at the clinical experimental stage (56, 60, 63)	Relatively easy to administer and requires few specialty skills (65)
			An ideal choice for targeting the organs in the abdominal cavity (66)
Disadvantages	Significant challenges in accessing deep lesions (54, 55, 58, 59)	Requires highly selective tissue targets (55)	Absorbed slower than intravenous injection (65)	Limited to central nervous system tumors (68)	Applied only to small animals in which veins are difficult to find (65)
	Complex procedures make repeat dosing difficult (61, 63)	Physiological barriers such as blood-brain barrier and oncolytic virus elimination by the immune system (55)
	Mostly applied in vitro experiments (39, 42, 44–47)	This route of administration, if any, would be the most likely to lead to toxicity (65)