Abstract: Methods and apparatus provide for treating and/or preventing tumor growth and/or spread, and/or other conditions in which Matrix Metalloproteinase (MMP) protein has been implicated in a patient, comprising: generating at least one specific and selective electric signal that when applied to electrodes, one or more coils, or other field generating devices operatively disposed with respect to targeted tissue causes the generation of a specific and selective electric field in the targeted tissue that substantially down-regulates the gene expression of MMP protein in said targeted tissue as measured by mRNA production; and exposing said targeted tissue to the specific and selective electric field generated by said electrodes, one or more coils, or other field generating devices upon application of said at least one specific and selective electric signal thereto for a duration of between about 3-5 hours at predetermined intervals so as to selectively down-regulate the gene expression of MMP protein in said targeted