Cyclophosphamide pretreatment in tumor cryotherapy: a comparison with alternative drugs

The method of Turk and Lagrange for modulating immune responses in favor of the cell-mediated effector arm by using single high doses of cyclophosphamide 3 days before antigen has previously been shown to cause decreased rates of local tumor recurrence when adapted as an adjunctive therapy to cryosurgery in a murine model. This series of experiments compares cyclophosphamide, azathioprine, and methotrexate against cryosurgery alone in the same therapeutic protocol. Only cyclophosphamide gave enhanced numbers of cures; azathioprine caused an increase in metastases arising concurrently with local tumor recrudescence.