The esophagus is a tubular structure situated in the thorax and neck. The caudal part of the esophagus goes through the diaphragm into the stomach. The cephalad portion of the esophagus begins at the upper esophageal sphincter near the cricoaretenoid muscles and has a short cervical section prior to entering the thorax between the superior lobes of the lungs.

For cancer staging purposes, the esophagus is divided into four segments: the cervical esophagus (above the thoracic inlet), the upper thoracic esophagus (from the thoracic inlet to the tracheal bifurcation), the mid thoracic esophagus (from the tracheal bifurcation to a point approximately 8 cm distally) and the lower thoracic esophagus (the remaining esophagus to the gastroesophageal junction). The portion of the esophagus involved becomes important during nodal staging (see below).

There are two main histologic types of cancer which arise in the esophagus. The first is squamous cell cancer, which appears to be related to tobacco, alcohol and dietary factors. The other is adenocarcinoma, which appears to be related to injury associated with chronic reflux of gastroduodenal contents. An example of a distal esophageal adenocarcinoma is shown in the video.

Therapy of esophageal cancer is determined by the stage of the cancer. Surgery is performed for early stage disease, surgery plus additional therapy for more advanced local disease, and palliative treatment for incurable metastatic disease. Staging determines a T stage (tumor), an N stage (Lymph nodes) and an M stage (metastasis). Preoperative staging is referred to as clinical staging. Procedures used in clinical staging include physical examination, endoscopy, endoscopic ultrasonography, imaging studies using barium, and CT scanning. Pathological staging is done at the time of surgery and is noted with a small case "p".

Although TNM staging of the esophagus generally follows rules used for other GI malignancies, esophageal cancer staging does have some unique features. Tumor (T staging) is somewhat different in esophageal cancer since there is no serosa surrounding the esophagus. The following are the TNM-stages .

T1: Tumor involves the lamina propria or submucosa
T2: Tumor involves the muscularis propria
T3: Tumor involves the adventitia
T4: Tumor involves adjacent structures

The adjacent structures which are commonly involved with T4 lesions include the aorta, pleura/lung and pericardium/heart.

N0: No regional lymph node metastasis
N1: Regional lymph node metastasis

The regional nodes are shown

M1a: Lower thoracic esophagus: metastasis in celiac lymph nodes;
Mid-thoracic esophagus: not applicable;
Upper thoracic esophagus: metastasis in cervical nodes

M1b: Lower thoracic esophagus: other distant metastasis;
Mid-thoracic esophagus: nonregional lymph nodes and/or other distant metastasis;
Upper thoracic esophagus: other distant metastasis

T1 N0 M0 T2 N0 M0 T3 N0 M0 T1 N1 M0 T2 N1 M0 T3 N1 M0 T4 Any N M0 Any T Any N M1a Any T Any N M1b

Nodal staging of the esophagus is somewhat complicated, due to the length of the esophagus and the various lymphatic sites of potential spread. The anatomic considerations are important in making this distinction. For example, Supraclavicular nodes are regional for the cervical esophagus (N1), but are considered metastatic (M1) for the lower esophagus.

There is a unique stage of thoracic esophageal cancer known as Stage IVA. Although stage IV is generally considered incurable- stage IVA patients can sometimes have durable responses and are often treated with curative intent, whereas in stage IVB, therapy is always palliative.

Stage IVA occurs when cancer of the distal esophagus is associated with nodes along the celiac trunk, or cancer of the upper thoracic esophagus is associated with supraclavicular lymph nodes.

Although this may seem to be somewhat arbitrary, a patient with supraclavicular lymph node involvement could have stage IIB or III disease if the primary tumor was in the cervical esophagus, stage IVA if the primary tumor was in the proximal thoracic esophagus, or stage IVB if the primary tumor was in the distal thoracic esophagus. Treatment would be more aggressive for those with stage IIB, III and IVA disease.