A method and device for photodynamic therapy for treating cancer. The method includes: providing a photodynamic therapeutic device for treating cancer. The provided device includes a plurality of light emitting diodes that are positionable in proximity of a patient's body and are adapted to provide a light fluence to a lesion area. The method also includes administering an effective dose of a photosensitizer in the lesion area; positioning the device in proximity to the patient's body; and irradiating the patient's body.