Photodynamic therapy, a curative local treatment for esophageal squamous cell carcinoma, involves a photosensitizing drug (photosensitizer) with affinity for tumors and a photodynamic reaction triggered by laser light. Previously, photodynamic therapy was used to treat superficial esophageal squamous cell carcinoma judged to be difficult to undergo endoscopic resection. Recently, photodynamic therapy has mainly been performed for local failure after chemoradiotherapy. Although surgery is the most promising treatment for local failure after chemoradiotherapy, its morbidity and mortality rates are high. Endoscopic resection is feasible for local failure after chemoradiotherapy but requires advanced skills, and its indication is limited to within the submucosal layer by depth. Photodynamic therapy is less invasive than surgery and has a wider indication than endoscopic resection. Porfimer sodium (a first-generation photosensitizer) causes a high frequency of side effects related to photosensitivity and requires the long-term sunshade period. Talaporfin (a second-generation photosensitizer) requires a much shorter sun-shade period than porfimer sodium. Photodynamic therapy will profoundly change treatment strategies for local failure after chemoradiotherapy.

Photodynamic therapy, a curative local treatment for esophageal squamous cell carcinoma, involves a photosensitizing drug (photosensitizer) with affinity for tumors and a photodynamic reaction triggered by laser light. Previously, photodynamic therapy was used to treat superficial esophageal squamous cell carcinoma judged to be difficult to undergo endoscopic resection. Recently, photodynamic therapy has mainly been performed for local failure after chemoradiotherapy. Although surgery is the most promising treatment for local failure after chemoradiotherapy, its morbidity and mortality rates are high. Endoscopic resection is feasible for local failure after chemoradiotherapy but requires advanced skills, and its indication is limited to within the submucosal layer by depth. Photodynamic therapy is less invasive than surgery and has a wider indication than endoscopic resection. Porfimer sodium (a first-generation photosensitizer) causes a high frequency of side effects related to photosensitivity and requires the long-term sunshade period. Talaporfin (a second-generation photosensitizer) requires a much shorter sun-shade period than porfimer sodium. Photodynamic therapy will profoundly change treatment strategies for local failure after chemoradiotherapy.

Many techniques have been developed to reduce the number of missed lesions during colonoscopy screening. Autofluorescence imaging (AFI) is one of the newly developed image-enhanced endoscopy (IEE) techniques, which functions similar to narrow band imaging (NBI) and flexible spectral imaging color enhancement (FICE), that can improve the detection and characterization of both polypoid and non-polypoid colonic neoplasms by enhancing their macroscopic features. We have previously reported that AFI, when used in combination with a transparent hood mounted on the tip of the endoscope to maintain distance from the colonic mucosa, results in the detection of approximately 1.6 times more colorectal neoplasms than conventional white light (WLI) colonoscopy. We have also revealed that AFI results in a higher flat neoplasm detection rate than WLI. Because the images of colorectal lesions visualized using AFI differ between histological lesion types, AFI also offers the possibility of differentiating neoplastic from non-neoplastic lesions. However, the difference between neoplastic and non-neoplastic lesions in the images generated using AFI relies on the density of the magenta coloring of the image and is therefore somewhat subjective. Recent studies suggest that NBI with magnification may be a superior modality for characterizing the neoplastic status of small colonic polyps. Although further developments are needed, the recent development of IEEs allows us to efficiently detect and differentiate colorectal neoplasms during colonoscopy screening. This article reviews the use of AFI in the diagnosis of colorectal neoplasms and discusses its advantages and limitations.
Colon ; Colonic Neoplasms ; Colonic Polyps ; Colonoscopy ; Colorectal Neoplasms ; Endoscopes ; Endoscopy ; Humans ; Light ; Mass Screening ; Mucous Membrane ; Narrow Band Imaging ; Optical Imaging