What Causes Stomach Cancer?

A diagnosis or a recommendation for cancer screening from your doctor is something no one wants to hear. No matter how young or old you are, it will always come as a shock.

The good news is most cancers, if caught early, are treatable, and stomach cancer is no exception.

Though it is uncertain what causes stomach cancer, it is one of the more common types of cancer in people over the age of 60. Therefore, risk factors and stomach discomfort will be things that your doctor will want to examine.

In fact, it is estimated that in 2021, there will be around 26,500 new stomach cancer diagnoses¹ in the United States.

Have you considered clinical trials for Stomach cancer?

We make it easy for you to participate in a clinical trial for Stomach cancer, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

What is stomach cancer?

Stomach cancer is cancer that affects the stomach. It is also commonly referred to as gastric cancer. About 90-95% of diagnosed stomach cancers² are adenocarcinomas, a type of cancer that affects the glandular secretory cells of the stomach lining.

In rare circumstances, other types of cancer may be found that affect the stomach. They include:

  • Primary Gastric Lymphoma

  • Gastrointestinal Stromal Tumor (GIST)

  • Neuroendocrine (Carcinoid) Tumors

  • Squamous Cell Carcinoma

  • Small Cell Carcinoma

  • Leiomyosarcoma

As a disease, stomach cancer means that malignant or cancerous cells have formed in one of the five layers in your stomach's lining:

  1. Mucosa is the first and innermost layer that contains the glands that release digestive juices. 

  2. Submucosa is the second layer that supports the mucosa and contains blood vessels, lymphatic vessels, and nerves.

  3. Muscularis is the third layer made of thick muscles. 

  4. Subserosa is the fourth layer that contains supporting tissues for the serosa.

  5. Serosa is the outermost layer that wraps around the stomach to confine it.

Most malignant cells will form in the mucosal layer and spread outward - so the closer you can catch it to the mucosa, the better.

Therefore, any stomach concerns should be discussed with your doctor. It also means that your doctor may keep a close eye on gastrointestinal issues when you reach a certain age.

Stomach cancer can show early warning signs. Some of the most common include:

  • Nausea or vomiting (with or without blood)

  • Rapid changes in appetite

  • Abdominal swelling

  • Changes in stool color or consistency

  • Frequent heartburn or indigestion

  • Abdominal pain or discomfort (normally above the belly button)

  • Easily fatigued

  • Feeling full after eating small amounts

  • Unintentional or unexpected weight loss

  • Anemia (lower-than-normal hemoglobin)

It is important to know that experiencing any of the above symptoms is not always an indication of cancer. Your doctor will need to check for other common gastrointestinal conditions that can mimic cancer, such as reflux or peptic ulcers.

Risk factors for developing stomach cancer

Although the causes of stomach cancer are uncertain, certain things may increase your risk of developing it. Some of these factors you can change, others you cannot.


According to MOFFITT Cancer Centers³, if you are a smoker, have a poor diet, or suffer from obesity, your chances of developing stomach cancer will be higher. Drinking alcohol can also trigger problems for some people.

Along with your diet and lifestyle, eating high amounts of salt can increase your risk. This includes eating a lot of foods that have been preserved through drying, salting, pickling, and smoking.

Working in areas that expose you to certain types of dust or fumes can damage your stomach and increase your overall risk. This may include working around coal, rubber, or metal.


Your ethnicity can play a role in your likelihood of developing stomach cancer. African Americans, Hispanics, and Asians are more commonly affected, according to the NCBI⁴.

Family history

If someone in your immediate family (parent, child, or sibling) has developed stomach cancer, you are more at risk for developing it as well. Other cancers in your immediate family history may also increase your risk, especially breast or ovarian cancer.

Genetics can also play a critical role in your risk of developing certain cancers. Stomach and breast cancer have both been linked with a higher risk if you have inherited mutations of the BRCA1 or BRCA2 genes.

Genetic disorders such as Lynch syndrome and familial adenomatous polyposis or FAP can also increase your risk.


Stomach cancer can be a concern for anyone over the age of 55. It is something your doctor will want to watch. Most diagnoses⁵ take place for individuals in their 60s and 70s.


Men are roughly two times more likely⁶ to develop stomach cancer than women.

Other health conditions

A pre-existing health condition such as pernicious anemia (a lack of B12 vitamin in your system) or achlorhydria (when your stomach lacks hydrochloric acid) can increase your risk of developing stomach cancer. Another possible risk factor is having previous stomach surgeries.

If you have what is called "H. Pylori infection" and it has been a long-term condition, it can also lead to pre-cancerous changes in the lining of your stomach. There is also new evidence of a link with Epstein-Barr virus infections, which have been found in 5-10% of patients with stomach cancer⁷.

Lifestyle changes that may reduce your risk

Even if you have several risk factors working against you, this does not mean you cannot overcome them. You may need to make some lifestyle changes. For instance:

Stop smoking

Smoking increases your risk for several types of cancer. It can also increase your risk of stomach cancer. The sooner you stop, the healthier you will be. 

Eat a healthier diet

Try to cut down on eating processed or salty foods. Fresh fruits (especially citrus fruits) and vegetables are much healthier and can help reduce your risk. This will also help you maintain a healthier weight, which will make you feel great and prevent other health concerns.

Stay active

The more active you are, the healthier you will be. This may also increase your ability to fight cancer.

Avoid excessive alcohol consumption

Frequent and too much alcohol consumption can negatively affect your stomach. 

How to reduce the risks with unchangeable factors

The key to understanding your risk of a stomach cancer diagnosis is to live a healthy lifestyle and talk openly with your doctor about your concerns.

Once you express your concerns, there are screening options⁸ available. Your doctor can help you find the right screening options for your situation.

The most common screening tools for gastrointestinal issues include:

  • Obtaining your full medical history

  • Performing a full physical examination

  • Gastrointestinal endoscopy is where the doctor inserts a small camera into your mouth, down into your stomach, and intestines to look for any signs 

  • CT scans or PET scans (Positron Emission Tomography) are useful as they allow the doctor to see spread beyond the stomach or into lymph nodes. PET scans are especially helpful to illuminate cancer cells if they are present 

  • Biopsies can be done if your doctor notices anything suspicious in your scans or the endoscopic examination

  • Endoscopic ultrasounds are useful in diagnosing and treating stomach cancer

Each of these screenings can allow your doctor to further assess your risk factors.

Learn more about how stomach cancer is diagnosed.

The lowdown

Stomach cancer can be linked to your genetics, your family history, or your lifestyle. Ultimately, if you have concerns, your first step should be to talk to your doctor about your risk factors and how to overcome them.

  1. Key Statistics About Stomach Cancer | American Cancer Society

  2. Stomach Cancer | National Organization for Rare Disorders

  3. Stomach Cancer Risk Factors | Moffitt Cancer Center

  4. Gastric cancer: prevention, risk factors and treatment (2011)

  5. Stomach Cancer: Statistics | Cancer.Net

  6. Key Statistics About Stomach Cancer | American Cancer Society

  7. Risk factors for stomach cancer | Cancer Treatment Center of America

  8. Tests for Stomach Cancer | American Cancer Society

Have you considered clinical trials for Stomach cancer?

We make it easy for you to participate in a clinical trial for Stomach cancer, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

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