The effect of various therapeutic solutions including colloidal chromic 32P via an intratumoral injection on the tumor physiological parameters of AsPC-1 human pancreatic tumor xenografts in nude mice.

To overcome the physiological barrier in solid tumors (i.e., tumor hypertension), a large volume of material is required via an intratumoral injection. Alternatively, a method of reduction in tumor hypertension is also feasible. In this study, we focused on the physiological response after an intratumoral infusion of various therapeutic agents. Tumor interstitial fluid pressure (TIFP) was intermittently monitored for up to 7 days after treatment using AsPC-1 human pancreatic tumors in nude mice. Macroaggregated albumin (MAA), colloidal chromic 32P (32P-CP), albumin, dexamethasone, 5-fluoro-2'deoxyuridine, dextrose, saline, and trypan blue increased TIFP within approximately 5 min, and TIFP returned to the original level within 1 h, except in the case of MAA and 32P-CP. We also found that the maximal uptake for AsPC-1 tumors in both the exponential and plateau growth phases occurred at approximately 100 min postincubation; the maximum value in the exponential growth phase was approximately 2 times less than that of plateau growth phase (P < 0.01). Therefore, this study supports intralesional 32P-CP brachytherapy for nonresectional pancreatic cancer patients. This may offer a promising treatment modality for delivering high doses of tumor-selective radiation, mainly due to two physiological mechanisms: (a) the high adherence of 32P-CP to the infused regions; and (b) reduction in either tumor blood flow or TIFP by this therapeutic colloid.