What is esophageal cancer? How is it staged/classified?

Esophageal cancer is a malignant tumor that occurs in the esophagus and originates from the epithelial cells of the esophagus.

Under constant stimulation by multiple internal and external factors, normal esophageal tissue cells undergo repeated processes of injury, repair, and accumulation of genetic mutations, gradually forming squamous epithelial hyperplasia or columnar epithelial metaplasia.

Squamous epithelial hyperplasia (Figure 1) is an abnormal proliferation of otherwise normal squamous epithelial cells in the esophagus. It is a benign lesion, but requires regular gastroscopic monitoring and vigilance for cancer if moderate to severe atypical hyperplasia is found.

Columnar epithelial metaplasia (Figure 2) is a precancerous lesion in which the squamous epithelium is covered by abnormal columnar epithelium that may further develop into adenocarcinoma.

When these stimuli reach a “tipping point,” the cells can “grow” uncontrollably and become cancerous.

Figure 1

Figure 2

Which types of esophageal cancer are classified

According to the pathological type, esophageal cancer is mainly divided into squamous carcinoma and adenocarcinoma, which can be divided into 4 subtypes: simple adenocarcinoma, adenosquamous carcinoma, mucinous epidermoid carcinoma, and adenoid cystic carcinoma. There are few other pathological types of esophageal cancer, such as basal cell carcinoma, neuroendocrine carcinoma, and esophageal sarcoma, all of which are very rare.

Squamous carcinoma is a tumor that forms in the squamous cells of the esophagus, usually at a physiologic or pathologic stricture that occurs in the middle or upper part of the esophagus. In China, about 90% of esophageal cancers are squamous.

Adenocarcinoma is a malignant tumor that occurs in the submucosa of the esophagus, or from the cardia glands. Adenocarcinoma is the predominant type in Europe and the United States.

To learn more about the difference between squamous carcinoma and adenocarcinoma, please read:

Staging of esophageal cancer

Clinically, physicians also staging esophageal cancer based on the morphology observed endoscopically or in the resected specimen. The significance of staging is to select the most appropriate treatment and to determine the outcome after treatment.

A long time ago, doctors divided esophageal cancer into early-stage staging and intermediate-stage staging. Early stages include cryptic, cachectic, plaque, and papillary; middle and late stages include medullary, myxomatous, ulcerative, indurated, intraluminal, and undetermined, but they are not used much anymore.

Today, physicians can determine lesions directly under endoscopy, and two guidelines are often referred to clinically: one from the Japanese Esophageal Cancer Association and the other from the Chinese consensus guidelines. As a neighbor in East Asia, the incidence of esophageal cancer in Japan is very similar to that in China, also predominantly squamous carcinoma, which is of reference value in the diagnosis and treatment.

Taken together, these two guidelines now often classify early-stage esophageal cancer into 3 types, namely, elevated above 1.2 mm (subdivided into tipped and non-tipped); depressed greater than 0.6 mm in depth; and flat in between, which can be subdivided into superficially elevated (less than 1.2 mm above planar height), completely flat, and superficially depressed (less than planar height). less than 0.6 mm ) (Figure 3).

Progressive esophageal cancer can be classified as augmented, locally ulcerated, ulcer-infiltrating, diffusely infiltrating, and undetermined (Figure 4).