The invention provides in part methods of treating cancers of a specific organ or tissue by administering a composition that is antigenically specific for one or more microbes that are pathogenic in the specific organ or tissue in which the cancer is situated. The formulations of the invention thereby facilitate activation of an immune response to a cancer in a particular tissue or organ. The compositions may for example include killed or attenuated microbial pathogens, such as whole killed bacterial cells, and may be administered at sites distant from the cancer, for example the skin. In some embodiments, microbial species of endogenous flora that are known to cause infection in the relevant organ or tissue may be used in the formulation of the antigenic compositions. In alternative embodiments, exogenous microbial pathogens that are known to cause infection in the relevant organ or tissue may be used in the formulation of the antigenic compositions. The administration of the immunogenic compositions may be repeated relatively frequently over a relatively long period of time. In embodiments for intradermal or subcutaneous injection, dosages may be adjusted so that injections reproduce a consistent, visible, delayed inflammatory immune reaction at the successive site or sites of administration.