Focal chemotherapy of brain tumours using semipermeable membranes

Semipermeable silastic rubber membranes can be used to diffuse focally a variety of chemicals including antitumour drugs. Of the eight drugs tested, in vitro tests showed the best diffusion with dactinomycin, mithramycin, and oncovin, and the poorest diffusion with bleomycin, fluorouracil, and thiotepa. Biological testing was performed with mithramycin, dactinomycin, and oncovin using tissue cultures of human glioblastoma and subcutaneous implants of mouse ependymoblastoma. All three drugs caused rapid tissue culture cell death with direct injection, and impeded tumour growth when given intraperitoneally. Dactinomycin by silastic diffusion proved more effective than mithramycin against tissue cultures, but neither drug had a significant effect against local tumours treated with implanted drug capsules. Silastic diffusion of oncovin reduced tumour sizes significantly ipsilateral to the implant, compared to contralateral implants and to untreated controls.