Gastric NETs vs Stomach Cancer: What's the Difference?

When you have autoimmune gastritis (AIG), seeing the word “tumor” on a pathology report can be terrifying. If your doctor mentions a gastric neuroendocrine tumor (gNET)—a type of tumor that forms in hormone-producing cells—you might understandably worry that you have “regular” stomach cancer. However, in the context of AIG, these are two entirely different conditions with very different behaviors, risks, and treatments.

The short answer is that the specific type of gNET caused by AIG (known as a Type 1 gNET) is generally slow-growing, highly treatable, and carries an excellent prognosis ^[1][2]. In contrast, regular stomach cancer (gastric adenocarcinoma) is a more aggressive disease that behaves differently and requires more intensive treatment ^[2][3].

How They Develop Differently

Type 1 Gastric NETs:
These small tumors are a direct result of the immune system’s attack on your stomach. In AIG, your body destroys the cells that make stomach acid ^[4]. Because your stomach acid is so low, your body tries to fix the problem by pumping out high levels of a hormone called gastrin ^[5]. Over time, this chronic high gastrin overstimulates specific cells in the stomach lining (called ECL cells), causing them to grow and multiply ^[6]. This chain reaction—no acid, high gastrin, cell overgrowth—is what eventually forms a Type 1 gNET ^[4].

Note: Pathology reports sometimes just say “gNET” without a number. Type 1 is specifically the kind driven by high gastrin in AIG. Other types (like Type 2 or Type 3) have different causes and behaviors, so it is important to confirm with your doctor that yours is a Type 1.

Gastric Adenocarcinoma (“Regular” Stomach Cancer):
Adenocarcinoma develops from the glandular cells of the stomach lining. While having AIG does slightly increase your risk for this type of cancer due to long-term inflammation and changes to the stomach tissue ^[5], it is much less common in pure AIG compared to Type 1 gNETs, especially if you have never been infected with H. pylori bacteria ^[7].

Differences in Aggressiveness and Symptoms

• Behavior: Type 1 gNETs are known as “indolent” or slow-growing ^[2]. They are typically well-differentiated, meaning the cells look very much like normal cells, and they rarely spread to other parts of the body ^[8][9]. Gastric adenocarcinoma is much more aggressive and has a higher potential to spread ^[3].
• Symptoms: Type 1 gNETs are almost always “silent,” meaning they do not typically cause pain, nausea, or other symptoms on their own. They are usually only discovered during a routine endoscopy.
• Outlook: Because Type 1 gNETs are so slow-growing and non-aggressive, they have a very favorable prognosis ^[1]. While they can recur (come back in the stomach after being removed), they are easily managed and rarely impact life expectancy ^[10][11].

Differences in Treatment

Because they behave so differently, doctors treat Type 1 gNETs and adenocarcinomas in completely different ways.

• Treating Type 1 gNETs: These are usually managed very conservatively. Most often, a gastroenterologist will simply remove the small tumors during a routine upper endoscopy (a procedure called endoscopic resection) ^[12][13]. While small tumors are easily removed this way, larger tumors (usually over 1 to 2 centimeters) may occasionally require surgery ^[12]. Afterward, you will need regular follow-up endoscopies (often every 1 to 2 years, depending on your doctor’s advice) to monitor for any new growths ^[10]. If the tumors frequently recur, doctors might use a medication called a somatostatin analog to help lower gastrin levels ^[14][15].
• Treating Adenocarcinoma: Because of its aggressive nature, regular stomach cancer typically requires major surgery, such as removing part or all of the stomach (gastrectomy), often combined with lymph node removal, chemotherapy, or radiation ^[16][17].

The Bottom Line

If you are diagnosed with a Type 1 gNET as a result of autoimmune gastritis, it is important to know that this is not the same as aggressive stomach cancer. While you will need regular monitoring to keep an eye on your stomach lining, Type 1 gNETs are highly manageable and behave in a very slow-growing, non-aggressive way.