What Causes the Different Types of Esophageal Cancer?

Esophageal cancer is not a single disease. The esophagus—the muscular tube that carries food from your throat to your stomach—is lined with different types of cells. The type of cancer a person develops depends on which specific cells become abnormal. Squamous cell carcinoma usually develops in the upper or middle part of the esophagus and is most strongly associated with a history of smoking, heavy alcohol use, and certain dietary factors. Adenocarcinoma typically forms in the lower esophagus near the stomach and is strongly linked to chronic acid reflux, a condition called Barrett’s esophagus, and central obesity.

Understanding the differences between these two main subtypes helps explain the different risk factors associated with them.

A Note on Risk Factors vs. Causes: It is natural to search for a reason after a cancer diagnosis, but it is important to know that medical research identifies risk factors—things that increase probability across a large population—not definitive personal causes ^[1]. Having a risk factor does not mean you caused your cancer. Many people with esophageal cancer have no clear explanation, and an individual diagnosis is usually the result of a complex mix of susceptibility and exposures ^[2].

Squamous Cell Carcinoma (SCC)

The inner lining of most of your esophagus consists of flat, thin cells called squamous cells. When these cells undergo genetic changes and grow out of control, it results in squamous cell carcinoma. This type of cancer is most frequently found in the upper and middle sections of the esophagus ^{[3] [4]}.

SCC is generally associated with environmental and lifestyle factors that can chronically irritate the esophageal lining over time:

• Tobacco and Alcohol: Smoking and heavy alcohol use are well-established risk factors for SCC ^[5]. When combined, tobacco and alcohol significantly amplify inflammation and DNA damage in the esophageal cells ^{[6] [7]}.
• Thermal Exposure: Some observational studies have associated SCC with regularly drinking very hot beverages (such as tea steeped at high temperatures), which may cause repeated thermal irritation to the esophagus ^[8]. Allowing hot drinks to cool to a comfortable temperature is a sensible precaution.
• Diet and Nutrition: Observational studies have linked a lower intake of fresh fruits and vegetables (specifically carotenes and lutein) and certain minerals like selenium and zinc to a higher risk of SCC ^{[9] [10]}. However, this may reflect a person’s overall nutritional status rather than proving that a single deficiency causes cancer. Do not start high-dose supplements without consulting your doctor, as they are not a proven cancer treatment.
• Esophageal Stasis: Conditions that cause food to pool and sit in the esophagus over a long period, such as achalasia (a condition where the esophagus fails to empty properly), can also lead to long-term irritation and contribute to SCC risk ^[11].

Adenocarcinoma

Adenocarcinoma starts in glandular cells—cells that produce mucus. It typically appears in the lower esophagus near the junction with the stomach, often as a response to chronic injury ^[12].

The risk factors for adenocarcinoma are closely linked to reflux and metabolic pathways:

• Chronic Acid Reflux (GERD): Frequent, long-standing acid reflux is a major associated risk factor for adenocarcinoma ^{[13] [14]}. Over time, stomach acid repeatedly washes into the lower esophagus, altering the cellular environment.
• Barrett’s Esophagus: In response to continuous acid exposure, the normal flat cells of the lower esophagus can be replaced by glandular cells, a change called metaplasia ^[12]. This condition is known as Barrett’s esophagus, and it is the principal recognized precursor to esophageal adenocarcinoma ^[15]. However, most people with Barrett’s will never develop cancer ^[16]. It is also important to note that many adenocarcinomas are diagnosed without any prior known history of Barrett’s ^[17].
• Central Obesity: Carrying excess weight around the midsection increases physical pressure on the stomach, which can worsen acid reflux ^[13]. Additionally, fat tissue acts as an active organ, releasing inflammatory signals and hormones that may contribute to cancer risk through other metabolic pathways ^{[18] [19]}.

Important Safety Note: If you have been diagnosed with esophageal cancer, do not attempt a restrictive diet or intentional weight loss without your oncology team’s direct guidance. Esophageal cancer and its treatments often cause difficulty swallowing and dangerous, unintentional weight loss. Maintaining your nutritional intake and physical strength is a critical priority for your care.