Oesophageal Cancer

Oesophageal cancer for a curative or palliative treatment option, it is important to determine the depth of infiltration of the tumour into the oesophageal wall (T stage), and the presence of malignant regional lymph nodes (N stage) and distant metastases (M stage). For N stage, N0 and N1 indicate the absence or presence of regional lymph node metastases, respectively. Similarly, M0 indicates the absence and M1 the presence of distant metastases . Whether a malignant lymph node is defined as N1 or M1 depends on the location of the primary tumour. For example, malignant celiac lymph nodes are staged as M1a if the primary tumour is located in the distal part of the oesophagus, but as stage M1b if the tumour is located in the more proximal part of the oesophagus and as N1 if the tumour is located in the gastric cardia . Distant metastases from oesophageal cancer are most frequently detected in celiac and supraclavicular lymph nodes, liver, lung, and adrenal glands .Endoscopic ultrasonography (EUS) is often used to determine the depth of tumour invasion and the presence of malignant regional and celiac lymph nodes in patients with oesophageal cancer. Both computed tomography (CT) and F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) are commonly applied to determine whether malignant lymph nodes or distant metastases are present. It is known that EUS, CT, and FDG-PET each have certain limitations. For example, only lymph nodes in the proximity of the oesophageal and gastric wall can be visualised with EUS, as it has a limited penetration depth of approximately 5 cm. As a consequence, metastases in distant lymph nodes or organs can often not be detected by EUS. Computed tomography is not able to detect metastases in normal-sized lymph nodes. Furthermore, an enlarged lymph node may contain metastases, but can also be enlarged as a consequence of inflammation (Halvorsen and Thompson. The same is true for abnormal findings in the liver or adrenal glands, for which it is not always clear whether these are metastases or not. Detection of metastases by FDG-PET is based on an altered tissue glucose metabolism. Biochemical changes are known to appear earlier in time than structural changes and also they are more specific. Nevertheless, lesions less than 1 cm in diameter can be missed by FDG-PET.