Extended treatment of tumors through vessel occlusion with light activated drugs

Methods of treating diseases of a subject through selective occlusion of blood vessels. The methods include identifying and/or mapping the blood vessels supplying nutrients to the diseased or unwanted tissue, delivering an appropriate dose of an occlusion-forming photosensitizer to the subject, and exciting the photosensitizer with sufficient light irradiation in the vicinity of the blood vessels to cause vessel occlusion. The vessel occlusion cuts off nutrient supply to the diseased or unwanted tissue resulting in cell death of that tissue and any other tissue served by the occluded vessels.