Youichi Kumagai

Dynamism of tumour vasculature in the early phase of cancer progression: outcomes from oesophageal cancer research

The vascular structure of cancer changes during tumour progression. A particularly dramatic change occurs during the early phase of progression when in situ tumour is transformed to invasive cancer. Recent advances in morphological investigations have made it possible to visualise and characterise the microvascular-network alterations. In addition, laboratory studies have also revealed the molecular profile--the changing levels of expression of different proteins--of cancer progression, which has helped to advance understanding of the mechanism of carcinogenesis. In this review, we discuss recent outcomes of research of oesophageal cancer and consider the responses of the vascular network and the development of new blood vessels during the early phase of cancer progression. Such considerations will be useful not only for understanding vascular biology but also for exploring novel diagnostic, therapeutic, and preventive approaches targeting early stage or latent phase human cancer.

ANGIOGENESIS IN SUPERFICIAL ESOPHAGEAL SQUAMOUS CELL CARCINOMA : MAGNIFYING ENDOSCOPIC OBSERVATION AND MOLECULAR ANALYSIS

Observations of esophageal squamous cell carcinoma using magnifying endoscopy have now been carried out extensively and, as a result, it has become clear that the morphology of the microvessels evident at the tumor surface reflects the depth of tumor invasion. In M1 and M2 cancer, the surface microvasculature reveals dilation and elongation of the intrapapillary capillary loops (IPCL). However, at this stage, some immature capillaries resembling IPCL also arise inside the tumor and, therefore, the view of the microvasculature should be described as one showing ‘intermixing of modified IPCL and IPCL‐like immature capillaries (IPCL‐like abnormal capillary)’. As cancer invades into the muscularis mucosa (M3 or deeper), an obviously dilated and irregularly branched tumor‐specific vasculature, more accurately described as ‘neovasculature’, can be observed. From our magnifying endoscopy observations and studies of the molecular profile of early esophageal cancer, we conclude that two major angiogenic steps exist in precancerous and M3 lesions in the early phase of cancer progression. In addition, it is now possible to study cell morphology using an endocytoscope with a much higher magnification (×400–×1000) than magnifying endoscopes currently on the market. The histology revealed in this way may reduce the need for conventional biopsy histology in the future.

Palisade vessels as a new histologic marker of esophageal origin in ER specimens from columnar-lined esophagus.

It is difficult for surgical pathologists to determine the origin of tissues in samples taken from the columnar-lined esophagus (CLE) or stomach by biopsy or endoscopic resection (ER) on the basis of histologic examination alone. We examined histopathologically a single section (5 to 22 mm in size; mean, 12 mm) from each of 66 cases of CLE (36 short segments, 30 long segments) from German patients with reference to 3 histologic markers of esophageal origin: esophageal glands proper and/or ducts, squamous islands, and double muscularis mucosae, all of which had been reported previously, and palisade vessels as a new histologic parameter as well. Palisade vessels were defined histologically as veins >100 &mgr;m in size in and above the original muscularis mucosae. Esophageal glands proper and/or ducts, squamous islands, and double muscularis mucosae were seen in 33%, 18%, and 71% of the specimens, respectively. Palisade longitudinal vessels were observed in 78% and 63% of specimens of short-segment and long-segment CLE, respectively. Palisade vessels were never seen in ER specimens from the stomach or in the middle esophagus and stomach among control autopsy specimens. At least 1 of these 4 markers was seen in 88% of the sections. Therefore, ER specimens were confirmed to originate from CLE in 88% of single histologic sections of CLE on the basis of histologic examination alone.

MAGNIFYING ENDOSCOPIC OBSERVATION OF THE UPPER GASTROINTESTINAL TRACT

Recent advances in technology enable us to obtain more detailed information during endoscopic procedures. Diagnosis of the pit pattern or microvascular architecture allow the earlier detection of neoplastic lesions in the gastrointestinal tract. These advances have led to the enhanced selection of appropriate treatments. Cancers that are discovered at an early stage can be treated by mucosal resection, whereas advanced cancers are treated with surgery. Recently, some groups have tried to acquire direct in vivo histological images of gastrointestinal mucosa (virtual histology or optical biopsy). Now optical coherence tomography (OCT), confocal laser endoscopy and endo‐cytoscopy systems enable this conception. However, none of these techniques has been proven, although some investigators have been able to use them to enhance cancer detection, and have reported the usefulness of these techniques. The present review assesses the strengths and weaknesses of these technologies, and describes the magnifying observations of the upper gastrointestinal tract using magnifying endoscopy equipment available on the market as well as newly developed endo‐cytoscopy systems. Published and unpublished data for this review were identified by searches of MEDLINE, Register of Cancer Trials: National Cancer Institute (http://cancertrials.nci.nih.gov/) and references from relevant articles. We also contacted researchers. The authors’ own database of references was also used. The search items were as follows: magnifying endoscopy, endo‐cytoscopy system, confocal endoscopy, optical coherence tomography, contact endoscopy, esophageal cancer, Barrett’s esophagus, Barrett’s esophageal cancer, gastric cancer, colon cancer, chromoendoscopy, methylene blue etc.

ENDOCYTOSCOPIC OBSERVATION OF ESOPHAGEAL SQUAMOUS CELL CARCINOMA

The endocytoscopy system (ECS), adapted for clinical use in 2003, is an ultra‐high‐power magnifying endoscope that allows observations at the cell level. ECS is based on the technology of light‐contact microscopy. The most evident use of ECS is for real‐time, high‐resolution diagnosis of nuclear abnormalities, mainly in patients with esophageal cancer. Up to now, three different types of ECS have been available. This diagnostic tool makes it possible to omit histological examination of biopsy samples in approximately 84% of esophageal squamous cell carcinoma, as evidence for both an increase of cell density and nuclear abnormalities is considered to be convincing proof that a lesion is malignant. Here we describe the features of ECS and the background that led to its development, and review the published literature pertaining to the observation of esophageal neoplasms using ECS.

Current status and limitations of the newly developed endocytoscope GIF‐Y0002 with reference to its diagnostic performance for common esophageal lesions

Objectives:  To investigate both neoplastic and non‐neoplastic lesions of the esophagus and to clarify the features of the surface cell morphology using a newly developed endocytoscope, the GIF‐Y0002.

Angiogenesis in Superficial Esophageal Squamous Cell Carcinoma: Assessment of Microvessel Density Based on Immunostaining for CD34 and CD105

OBJECTIVE The esophagus is the only organ where changes in the superficial microvasculature from normal squamous epithelium to invasive cancer are evident by magnifying endoscopy. We investigated in detail the features of angiogenesis in early-stage esophageal cancer using CD34 and CD105 immunostaining, and also the correlation between angiogenesis and mononuclear cell infiltration. MATERIALS AND METHODS Using 10 samples of normal squamous epithelium, 7 samples of low-grade intraepithelial neoplasia, and 45 samples of superficial esophageal cancer, we determined the microvessel density at hot spots showing positive staining for CD34 and CD105. We observed the histological features of CD34- and CD105-positive microvessels that corresponded to observations made by magnifying endoscopy. We then investigated the correlation between microvessel density and each histological situation or the grade of mononuclear cell infiltration. RESULTS The histological features of CD34- and CD105-positive microvessels were able to explain the morphological changes in the microvasculature during cancer progression observed by magnifying endoscopy. The microvessel density for CD34 or CD105 was significantly correlated with each of the histological types (P < 0.001, rS = 0.51 and 0.76, respectively). Mononuclear cell infiltration at CD105 hot spots was most frequent in M1 and M2 cancer (94.7%). The correlation between the degree of mononuclear cell infiltration and microvessel density for CD105 staining was also significant (P < 0.001, rS = 0.49). CONCLUSIONS The microvessel density based on CD34 and CD105 immunostaining can be used to corroborate observations of superficial esophageal squamous cell carcinoma made by magnifying endoscopy. Mononuclear cell infiltration may play an important role in angiogenesis at the early stage of cancer progression.

A tiny esophageal cancer diagnosed accurately by magnifying endoscopy and endocytoscopy: report of a case

An 82-year-old woman presented for a periodic endoscopic examination after radiotherapy and endoscopic mucosal resection (EMR) of a cancer in the esophagus. Conventional endoscopy demonstrated a tiny, flat, reddish lesion about 1 mm in diameter proximal to the scar of the previous esophageal EMR. Observation after iodine staining showed an apparent unstained area in the lesion. Magnifying observation using a Q240Z (Olympus, Tokyo, Japan) revealed a clearly demarcated aggregation of dilated intrapapillary capillary loops in this part of the lesion. Endocytoscopic observation (XEC120U prototype; Olympus) showed increased cellular density and irregularity of the epithelial nuclei. Endoscopic mucosal resection of the lesion was performed. Pathological studies of the resected specimen revealed a squamous cell carcinoma, maximal diameter 920 μm, confined to the epithelium. We believe that the Endocytoscope has the potential to reduce biopsy histology in cases of esophageal squamous cell carcinoma.

Usefulness of indocyanine green angiography for evaluation of blood supply in a reconstructed gastric tube during esophagectomy.

We report a case of necrosis of a reconstructed gastric tube in a 77-year-old male patient who had undergone esophagectomy. At the time of admission, the patient had active gastric ulcers, but these were resolved by treatment with a proton pump inhibitor. Subtotal esophagectomy with gastric tube reconstruction was performed. Visually, the reconstructed gastric tube appeared to be well perfused with blood. Using indocyanine green (ICG) fluorescence imaging the gastroepiploic vessels were well enhanced and no enhancement was visable 3 to 4 cm from the tip of the gastric tube. Four days after esophagectomy, gastric tube necrosis was confirmed, necessitating a second operation. The necrosis of the gastric tube matched the area that had been shown to lack blood perfusion by ICG angiography imaging. It seems that ICG angiography is useful for the evaluation of perfusion in a reconstructed gastric tube.

Magnifying endoscopic observation of superficial esophageal carcinoma

The depth of tumor invasion of esophageal cancers is one of the most important indicators for predicting lymph node metastasis, so much effort has been directed toward improving the diagnosis of tumor invasion, especially in cases of superficial esophageal cancer. Ultra‐high magnifying endoscopic observation for esophageal cancer was performed using an Olympus Q240Z, which has a 100 × magnifying capacity. We succeeded in observing looped capillary vessels inside the papillae (intrapapillary capillary loop: IPCL). The IPCL inside an m1 cancer showed abnormal changes such as ‘dilation, weaving, changes in caliber, variety of shapes’. Furthermore, we found that superficial esophageal cancers show characteristic changes according to the depth of invasion. In our investigation, the rate of accurate diagnosis using magnifying endoscopy for superficial esophageal cancers was 83.1% in cases for which fine pictures were obtained. Observations of the microvascular architecture of superficial esophageal carcinoma using magnifying endoscopy are useful for diagnosing the depth of tumor invasion, especially for superficial cancers with invasion reaching to the muscularis mucosae (m3) and slightly into the submucosa (sm1) esophageal cancer.