This invention relates to improved methods of photodynamic treatment and diagnosis of cancer and non-cancerous conditions, and in particular to improved enema preparations for use in such methods, said enema preparations comprising a photosensitiser which is 5-aminolevulinic acid (5-ALA) or a precursor or derivative thereof, e.g. a 5-ALA ester. Such preparations may further comprise one or more viscosity enhancing agents, mucoadhesive or mucolytic agents, penetration enhancers or chelating agents. The methods and preparations herein described are particularly suitable for use in photodynamic methods of treating and/or diagnosing cancer and non-cancerous conditions in the colon and/or rectum.
