Helicobacter Pylori: What Is it and How Can it Cause Stomach Cancer?

Gastric cancer, a malignant disease affecting the stomach, has been closely associated with the presence of Helicobacter pylori, a bacterium that can colonize the stomach lining and induce chronic inflammation. In this blog, we speak to Samer Hassan, M.D., a physician at INTEGRIS Health Cancer Institute at Southwest Medical Center, to learn about the link between stomach cancer and Helicobacter pylori infection, how to lower your risk and why effective treatment is so important.

What is Helicobacter pylori?

Helicobacter pylori (H. pylori) is an aggressive spiral-shaped bacterium that infects the stomach lining and causes gastritis (inflammation) and ulcers (open sores). The stomach has several layers to aid in digestion, absorb nutrients, protect against the corrosive nature of gastric acid and provide a barrier against harmful pathogens.

Of these layers, the mucosa (the innermost layer that produces mucus to protect the stomach lining) is most affected by H. pylori.

Once an infection occurs, Helicobacter pylori causes the stomach to produce more molecules that act as receptors for the bacteria. It also impacts the levels of stomach acid.

The effects of H. pylori can vary because there are different strains. Some people may remain asymptomatic, but if the bacteria stick around for a long time, various stomach and non-stomach-related issues can occur and cause chronic damage to the mucosal lining. The most common symptoms associated with H. pylori include dyspepsia (indigestion), frequent burping, stomach pain, weight loss, bloating, nausea, vomiting, loss of appetite and dark stools.

How do you get Helicobacter pylori?

Helicobacter pylori is highly contagious and spreads through direct contact, specifically via bodily fluids. This may occur through mouth-to-mouth contact when kissing or through fecal matter from contaminated food and water. For example, you may eat food or drink water that has come in contact with this bacteria and hasn’t been properly washed or cooked to the recommended temperature.

H. pylori is more common in underdeveloped countries due to crowded conditions, poor hygiene and poor sanitation. Children in these areas are most susceptible to developing an infection.

Why is the bacteria so infectious? H. pylori has the ability to neutralize the acidity of its surroundings in the stomach, which actually helps it survive. It produces an enzyme called urease, which helps counteract stomach acid by converting urea into ammonia. In other words, Helicobacter pylori excels at surviving in the stomach because it can make the stomach less acidic and hide from the body's defenses.

Helicobacter pylori and stomach cancer

Typically, Helicobacter pylori can be treated with antibiotics, which reduces the impact of symptoms. In some cases, the bacterial infection doesn’t produce any symptoms and you may be unaware you even have the disease. 

• But if it’s not properly treated or detected, the bacteria can linger and cause long-lasting stomach inflammation that leads to an increased cancer risk. Inflammation can cause DNA changes that trigger cancerous cells to grow in the stomach lining. Plus, damage to the lining exposes the body to chronic gastric acid exposure, which can pose a cancer risk. Together, this environment makes it more likely to develop gastric cancer at some point.
• From a global perspective, gastric cancer is the fifth-most common cancer. In the U.S., those numbers are lower for several reasons, including advancements in food preservation (lower risk of carcinogenic contamination) and a lower risk of H. pylori (this infection is more common in underdeveloped countries). 
• Gastric adenocarcinoma and gastric mucosa-associated lymphoid tissue (MALT) lymphoma are the two types of cancers associated with H. pylori.

Gastric adenocarcinoma

Gastric adenocarcinoma, the most common type of stomach cancer, originates in the glandular cells (cells that release mucus, hydrochloric acid and digestive enzymes) of the stomach lining.  

Research shows chronic inflammation from H. pylori leads to an increase in two types of adenocarcinoma in the stomach – gastric cardia cancer and non-cardia gastric cancer. Cardia is the area where the stomach meets the esophagus, so gastric cardia cancer simply means the cancer occurs at the top of the stomach near the esophagus. Non-cardia gastric cancer occurs in the main part of the stomach.

Tumors associated with stomach cancer grow slowly over time. However, it’s often discovered at an advanced stage.

MALT lymphoma

MALT lymphoma is a rare type of lymphoma that develops in the mucosa-associated lymphoid tissue, which plays an important role in immune function by defending against pathogens. MALT lymphoma is a type of non-Hodgkin lymphoma. 

Mucosa-associated lymphoid tissue can be found throughout the body, including in the gastrointestinal tract and respiratory tract. It contains a type of white blood cells called lymphocytes that help recognize and destroy foreign invaders. In the stomach, MALT lymphoma causes DNA changes in the lymphocytes. The abnormal cells grow uncontrollably to form tumors. Like gastric adenocarcinoma, MALT lymphoma grows slowly and can be treated if detected early enough.

What does H. pylori look like in stool?

The presence of H. pylori may lead to changes in stool appearance, color or consistency for some people. The most common example is blood in the stool that makes it dark or black. Ulcers can develop in the stomach or small intestine and, when these ulcers bleed, blood can make its way into the stool.

What is the most accurate test for H. pylori?

In the event symptoms develop and an infection is suspected, there are several ways to diagnose Helicobacter pylori infection. 

A urea breath test is considered the most accurate and reliable noninvasive test for detecting the presence of H. pylori. To conduct the test, you first breathe into a bag, then ingest a urea solution and breathe into the bag again. The before-and-after results are compared, as the presence of H. pylori will break down the urea solution and release carbon dioxide – a higher level of CO2 after drinking the solution confirms the presence of the bacteria. 

Your doctor may also request a stool sample to analyze bacteria in the feces or conduct an upper endoscopy, which uses a tiny camera to view the stomach. During an endoscopy, tissue from the stomach is removed for further testing.

How do you treat H. pylori?

Stomach inflammation caused by H. pylori takes a while to develop into precancerous conditions and eventually cancer, which furthers the importance of treating the infection early before it causes damage.

Treatment consists of a combination of antibiotics and acid-reducing medications such as proton pump inhibitors (PPIs) that block the enzyme responsible for producing stomach acid. PPIs don’t stop stomach acid production altogether, rather they reduce the amount produced so antibiotics are more effective in killing the bacteria.
For antibiotics, a multi-antibiotic approach is one way to minimize the risk of antibiotic resistance and improve overall treatment effectiveness.

Common antibiotics used to treat H. pylori include:

• Amoxicillin
• Clarithromycin
• Levofloxacin
• Metronidazole

In many cases, an approach called triple therapy is used. This involves a PPI alongside two antibiotics such as clarithromycin and amoxicillin.

Proton pump inhibitors can be found over the counter or via prescription. They include:

OTC PPIs

• Esomeprazole (Nexium)
• Lansoprazole (Prevacid)
• Omeprazole (Prilosec)

Prescription PPIs

• Pantoprazole (Protonix)
• Rabeprazole (AcipHex)

Additional medications used

A combination of medications is typically used to both treat the infection and help heal inflammation or any ulcers that develop.

Acid blockers (Cimetidine, famotidine and nizatidine): These medications limit histamine, a chemical that stimulates inflammation and initiates acid secretion in the stomach.

Misoprostol: This medication limits the amount of stomach acid produced while also protecting the stomach lining by increasing its resistance to acid.

Sucralfate: This medication treats ulcers by forming a protective barrier over open sores.

Can H. pylori come back?

H. pylori can return even if the initial bacteria are eliminated by effective treatment methods. Re-exposure can trigger a future infection – the recurrence rate ranges from 1.5 percent to 8.7 percent, depending on geographical and socioeconomic factors.

If you or a loved one has been exposed to Helicobacter pylori, it’s important to treat the infection to avoid long-lasting inflammation that can increase your risk of developing stomach cancer. Contact one of our gastroenterologists who specialize in diseases and illnesses of the GI tract. They can put a treatment plan together to limit the damage of H. pylori.