Table 4.

Strategies for local drug delivery: clinical impact based on expectations from drug therapy^a

Strategy	Effectiveness for CNS Malignancy	Toxicity/Adverse Effects Profile	Introduction into Clinical Practice	Repeated/Continuous Administration	Tumor Size and CNS Location
Implantable polymers	Failed phase III clinical trials.	Invasive procedure. Increases surgical complication rates.	Relatively simple.	Not feasible.	Limited to resectable tumors at a distance from CSF pathways.
Intracavitary drug delivery	Not established (few phase II studies).	Invasive procedure. Device-associated infections, reversible and irreversible neurotoxicity for some agents.	Limited. Requires multidisciplinary expert team approach.	Depending on the agent, may be possible for non-radioactive agents.	Limited to small tumor size or to tumors accessible for GTR
Convection-enhanced delivery	Failed phase II/III clinical trials. Some studies are still ongoing.	Invasive procedure. Some agents associated with neurotoxity or chemical meningitis.	Limited due to high complexity. Requires multidisciplinary expert team approach.	Limited and associated with increased rate of infections.	Limited by tumor size, mass effect, and CNS location.

Abbreviation: GTR, gross total resection.

^aFor references, please see text.