Abstract: A method of diagnosing cancer in a human patient comprising the steps of (i) obtaining a sample containing nucleic acid and/or protein from the patient; and (ii) determining whether the sample contains a level of hNeNa voltage-gated Na+ channel nucleic acid or protein associated with cancer. A method of treating cancer comprising the step of administering to the patient an agent which selectively prevents the function of hNe—Na voltage-gated Na+ channel. A genetic construct comprising a nucleic acid encoding a molecule capable of preventing the function of hNeNa voltage-gated Na+ channel expressed in a cell. The methods and compositions are particularly suited to prostate cancer.