Stomach polyps are abnormal tissue growths that form within the stomach. Although they are usually harmless, some stomach polyps have the potential to become cancerous.

Researchers and doctors do not fully understand what causes stomach polyps or increases a person’s risk of these growths. Due to this, as well as the fact that stomach polyps often cause no symptoms, diagnosis can be challenging.

This article provides more information about stomach polyps, including their causes, symptoms, risk factors, diagnosis, and treatment. It also explains the differences between some of the common types.

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Stomach polyps, or gastric polyps, are tissue growths that form inside a person’s stomach.

As a 2021 review explains, stomach polyps are more likely to form in the upper part of the stomach. Most stomach polyps are less than 2 centimeters in size and are benign, meaning that they are not cancerous.

The same review also states that 2–6% of people who undergo an endoscopy have stomach polyps. However, this does not necessarily mean that the same percentage of people in the general population have these polyps.

The stomach is an important and complex organ that breaks down the food that a person eats. It produces stomach acid for this purpose and secretes an inner layer of mucus to protect itself from the acid.

There are several different types of stomach polyp, which affect a person’s stomach in slightly different ways.

The most common stomach polyp types are:

  • Gastric hyperplastic polyps (GHP): These form when the stomach produces too many mucus-secreting cells.
  • Fundic gland polyps (FGP): These occur due to the stomach’s acid-producing cells becoming dilated and irregularly bundled.
  • Adenomatous polyps: These form when some of the cells in a person’s stomach develop in unusual but noncancerous ways.

Research shows that of the stomach polyps that doctors detect during an endoscopy, 17–42% are GHPs, 37–77% are FGPs, and 0.5–1% are adenomatous polyps.

Although most stomach polyp types are harmless, some stomach polyps occur due to the presence of cancerous cells. These account for about 1–2% of the stomach polyps that doctors find during endoscopies.

The majority of stomach polyps are symptomless.

However, when stomach polyps do cause symptoms, a person may experience:

It is advisable that anyone who regularly experiences the above symptoms seeks the advice of a doctor.

Scientists are uncertain what causes stomach polyps, and it is possible that different kinds of stomach polyps have different causes.

For example, there is evidence that GHPs may occur due to chronic stomach inflammation, although the exact mechanisms behind this link are currently unknown.

In contrast, experts believe that FGPs may arise when something forces the stomach to produce less gastric acid. This theory exists because FGPs are more likely to form in people who regularly use proton pump inhibitors (PPIs). As a 2021 article explains, PPIs work by suppressing gastric acid production.

Experts are also uncertain about the risk factors for stomach polyps.

Researchers have noted that older adults could be more likely than younger people to develop stomach polyps. They have also suggested that females may be more likely to have FGPs, whereas males may be more likely to have adenomatous polyps.

Other risk factors for stomach polyps may exist. For instance, the authors of a 2018 study suggest that the following may be risk factors for stomach polyps:

  • being aged 45–60 years
  • being a smoker
  • not exercising regularly

However, they note that the study had several limitations and state that more research is necessary on this topic.

Diagnosing stomach polyps can be difficult. As so many stomach polyps are symptomless, doctors detect more than 90% of them accidentally while performing an endoscopy for other reasons.

Additionally, stomach polyps are often small. For this reason, most of them do not show up on CT or MRI scans. Moreover, doctors cannot usually determine the type of stomach polyp by using endoscopy. Instead, they have to perform a biopsy, which involves removing a part of the polyp and sending it to a laboratory for testing.

If stomach polyps are asymptomatic and not cancerous, there may be no need for any form of treatment.

As a 2016 article explains, doctors sometimes recommend the removal of larger stomach polyps that they consider likely to become cancerous. However, they might advise against removing smaller stomach polyps because this procedure can have unwanted side effects, such as bleeding.

Other treatment options might help. For instance, a Helicobacter pylori infection can cause chronic stomach inflammation, which may itself cause GHPs. In about 70% of cases, people with GHPs will find that their stomach polyps regress after treatment for their H. pylori infection.

As the suppression of stomach acid secretion may cause FGPs, dietary changes might affect FGPs. There is some evidence that certain dietary patterns can lower stomach acid secretion. However, no existing research suggests that dietary interventions are safe and effective treatment options for stomach polyps.

Stomach polyps are often symptomless, so many people with these growths will not be aware of their presence. If doctors detect them during an endoscopy for another reason, they may not recommend removing them if they are small.

However, they may suggest further testing to confirm that the stomach polyps are benign.