Is an Ulcer Cancer? The Link Between Ulcers and Cancer

Most ulcers are not cancer. The vast majority of stomach ulcers, mouth sores, and skin ulcers are benign conditions that heal with appropriate treatment. But the relationship between ulcers and cancer is more than casual: in a large study of gastric ulcers, about 6% turned out to harbor a malignancy on biopsy, and the bacterium most responsible for peptic ulcer disease is also the strongest known risk factor for stomach cancer.¹ That overlap is why doctors take stomach ulcers seriously and why understanding the connection matters.

How Often a Gastric Ulcer Hides a Cancer

When a doctor sees an ulcer in the stomach during an endoscopy, the first question is whether it is a simple peptic ulcer or something more dangerous. In a cohort of 432 patients with gastric ulcers, 27 turned out to have dysplasia or a malignancy, including 19 adenocarcinomas, 5 lymphomas, and other cancers. That works out to a malignancy rate of about 6%.¹ An older study of 265 gastric ulcer cases found 37 were malignant, putting that figure closer to 14%.² The wide range reflects differences in the populations studied, but the message is consistent: a stomach ulcer that looks benign can still be cancerous, and the only reliable way to tell is to take tissue samples.

The overwhelming majority of malignant cases are caught on the first biopsy. In the larger cohort, 93% of cancers were identified at the initial endoscopy.¹ That is why current guidelines call for biopsying every gastric ulcer at first sight, not waiting to see if it heals on its own. A small number of cancers, however, are missed on the initial pass. The cancer yield of follow-up endoscopy after an initially benign biopsy was about 0.9% in that same study, which is low but not zero.

The Bacterium Behind Both Ulcers and Stomach Cancer

Helicobacter pylori is a spiral-shaped bacterium that colonizes the stomach lining of roughly half the world’s population. Its discovery in the 1980s upended the understanding of both peptic ulcers and gastric cancer, because this single organism turned out to drive both conditions.³ H. pylori infection causes chronic inflammation of the stomach lining and is the strongest known risk factor for gastric cancer, which remains one of the leading causes of cancer-related death worldwide.⁴

A landmark Japanese study followed over 1,500 patients for years and found that gastric cancers developed in about 3% of H. pylori-infected patients and in none of the uninfected ones.⁵ Among those infected, cancer rates varied by the type of stomach condition the patient had: roughly 5% of those with non-ulcer dyspepsia developed cancer, about 3% of those with gastric ulcers, and about 2% of those with gastric polyps. The relationship between infection, ulcers, and cancer is not a simple chain of one causing the next. Rather, H. pylori sets up the inflammatory environment in which both ulcers and cancer can emerge, sometimes in the same person, sometimes along different pathways.

Why Duodenal Ulcers Are Different

If gastric ulcers carry a real risk of hiding a cancer, you might assume duodenal ulcers do the same. They do not. In the same Japanese study, none of the 275 patients with duodenal ulcers developed gastric cancer.⁵ This finding is consistent across the literature and explains why guidelines treat the two types of ulcers very differently. Duodenal ulcers are almost never biopsied, while gastric ulcers almost always are.

The reason has to do with biology. Duodenal ulcers tend to occur in people whose H. pylori infection stays concentrated in one part of the stomach, causing high acid secretion but relatively little of the widespread inflammation that progresses toward cancer. Gastric ulcers, by contrast, often form in a stomach where the infection has spread across the lining and is already causing the type of chronic damage associated with precancerous changes. Same bacterium, different patterns of disease.

The Slow Path from Inflammation to Cancer

Stomach cancer almost never appears overnight. The progression from a healthy stomach lining to invasive cancer follows a well-described sequence of changes that unfold over years or decades. Researchers call it the precancerous cascade. It starts with chronic inflammation of the stomach lining, moves to loss of the normal gland structure, then to a change in the type of cells lining the stomach, then to abnormal pre-cancerous cells, and finally to invasive cancer.⁶ H. pylori infection is the trigger that kicks off the initial inflammation in most cases.⁷

Not everyone who has chronic gastritis will progress through every step. Most people infected with H. pylori never develop cancer. But the risk climbs the further along the cascade a person is. This is why detecting and treating the infection early matters, and why doctors pay attention to biopsy results that show intestinal metaplasia or dysplasia, which are the steps closest to cancer on this timeline.

Does Treating H. pylori Prevent Stomach Cancer?

If H. pylori drives both ulcers and cancer, the obvious question is whether killing the bacterium lowers cancer risk. The answer, based on pooled data from multiple trials, is yes. A recent meta-analysis found that eradicating H. pylori cut gastric cancer incidence by about 39% compared to controls.⁸ The benefit was especially pronounced in patients who had already had early gastric cancer removed endoscopically, where successful eradication cut the risk of a new cancer roughly in half.

Timing appears to matter. A study of peptic ulcer patients found that earlier eradication was associated with a lower risk of developing gastric cancer down the line.⁹ A separate long-term study tracked over 1,200 patients for 17 years after attempted eradication. Those in whom treatment succeeded developed gastric cancer at roughly half the rate of those in whom the infection persisted.¹⁰ The protection is real but not absolute. Even after successful eradication, some patients still develop cancer, especially if the stomach lining was already significantly damaged before treatment.

When the Ulcer Itself Is a Lymphoma

Gastric adenocarcinoma is not the only cancer linked to H. pylori. A less common but remarkable connection involves MALT lymphoma, a type of low-grade cancer of the immune tissue in the stomach lining. These tumors can look like ulcers on endoscopy and are closely tied to H. pylori infection.¹¹

What makes MALT lymphoma unusual is that treating the infection with antibiotics can make the cancer regress. In a long-term study of 105 patients with localized gastric MALT lymphoma, eradicating H. pylori led to complete or partial regression of the lymphoma in about three-quarters of cases.¹² Even some patients who tested negative for the bacterium at diagnosis responded to eradication therapy, though at lower rates. In one smaller study, the complete remission rate was 63% in infected patients versus 13% in those who appeared uninfected.¹³ This is one of the few situations in medicine where treating an infection can directly cure a cancer.

Follow-up Endoscopy and Why Healing Matters

Because a small percentage of apparently benign gastric ulcers turn out to be malignant, guidelines in the UK and elsewhere recommend a repeat endoscopy within 6 to 12 weeks to confirm the ulcer has healed.¹⁴ An ulcer that does not heal despite proper treatment raises suspicion. It may simply need more time or a different approach, but persistent non-healing is one of the classic warning signs that something more serious is going on.

Is the follow-up worth it? One analysis estimated that performing repeat endoscopy on 50 patients with an apparently benign gastric ulcer would identify one patient with a malignancy who would go on to survive at least five years after surgery.¹⁵ That ratio may sound low, but catching stomach cancer early, when it is still potentially curable, dramatically improves outcomes. Among patients with gastric ulcers, the long-term risk of stomach cancer remains elevated for years. A large Scandinavian study found that the risk stayed roughly 1.8 times the general population’s rate for as long as 24 years of follow-up.¹⁶

Newer Ways to Spot the Dangerous Ones

Distinguishing a benign gastric ulcer from a malignant one by eye alone is unreliable, which is why biopsy remains the standard. But newer endoscopic technologies are making the visual assessment better. Techniques like narrow-band imaging and autofluorescence endoscopy let doctors examine the fine surface pattern and blood vessel architecture around an ulcer in real time. In a study of 25 ulcers, irregular patterns seen under narrow-band imaging and abnormal autofluorescence in the ulcer margin were highly suggestive of malignancy, particularly adenocarcinoma.¹⁷ These tools do not replace biopsy, but they help endoscopists decide where to aim the forceps, which makes sampling more accurate.

Artificial intelligence is also entering this space. Deep learning models trained on thousands of endoscopic images are being developed to help distinguish benign peptic ulcers from gastric adenocarcinoma based on visual features alone.¹⁸ These systems are not yet part of routine practice, but they may eventually serve as a second set of eyes during procedures.

Cancer Fear and Stomach Symptoms

A significant share of people who see a doctor about stomach pain are motivated at least partly by the fear that their symptoms might be cancer. A qualitative study of patients over 50 with dyspepsia found that the perceived threat of cancer and the need for reassurance were key reasons for seeking medical attention. That worry was often fueled by a family member or friend’s experience with serious illness.¹⁹

That anxiety is understandable but often out of proportion to the actual risk. The vast majority of stomach ulcers are simple peptic ulcers that respond well to treatment with acid-lowering drugs and, when H. pylori is present, antibiotics. The cancer concern is legitimate enough to justify investigation, especially in older patients or those with alarm symptoms like unexplained weight loss, difficulty swallowing, or vomiting blood. But for most people, the news after endoscopy is reassuring.

Mouth Ulcers and Oral Cancer

The stomach is not the only place where ulcers raise cancer questions. Mouth ulcers are extremely common and almost always benign, but a small fraction turn out to be cancerous. UK guidelines suggest that any oral ulcer lasting more than three weeks should be referred for specialist evaluation. An audit of over 1,000 such referrals found that only about 18% of the patients referred actually had a malignancy, which means the system catches cancers but also generates a lot of false alarms.²⁰ The practical takeaway is simple: a mouth sore that heals within a couple of weeks is almost certainly nothing to worry about. One that persists, especially if it is painless, firm, or oddly shaped, deserves a closer look.

Ulcerative Colitis and Colorectal Cancer

Ulcerative colitis, a form of inflammatory bowel disease that causes recurring ulcers in the colon, carries a well-documented increase in colorectal cancer risk. The risk does not appear immediately at diagnosis. Instead, it begins to climb about 8 to 10 years after ulcerative colitis is first diagnosed and continues to rise with time.²¹ Factors that push the risk higher include a younger age at diagnosis, disease that affects more of the colon, more severe inflammation, a family history of colorectal cancer, and a coexisting liver condition called primary sclerosing cholangitis.

This is why people with long-standing ulcerative colitis are put on surveillance colonoscopy programs. The goal is to catch precancerous changes, known as dysplasia, before they progress. The connection here is not that colitis ulcers “become” cancer in a direct sense but that the chronic inflammation of the colon’s lining creates an environment where cancer is more likely to develop over time, much like the process H. pylori sets up in the stomach.

Chronic Skin Ulcers and Marjolin’s Ulcer

Skin ulcers that refuse to heal for months or years carry their own cancer risk. Marjolin’s ulcer is the term for a malignancy, most often squamous cell carcinoma, that arises in chronic non-healing wounds, old burn scars, or areas of longstanding inflammation.²² Despite having “ulcer” in the name, it is really a cancer that develops within damaged tissue. The latency period can be long, sometimes decades between the original injury and the appearance of the malignancy.²³

Marjolin’s ulcers are rare, but they tend to be aggressive when they do appear. The typical presentation is a chronic wound or scar that suddenly changes: the edges become raised, bleeding increases, or the wound starts growing after years of stability. Biopsied tissue usually shows well-differentiated squamous cell carcinoma, though other types of skin cancer are sometimes found.²⁴ The lesson for anyone living with chronic wounds or old scars is that any change in the wound’s appearance, particularly if it has been stable for a long time, warrants medical evaluation.

Barrett’s Esophagus and Esophageal Cancer

Chronic acid reflux can damage the lower esophagus and, over time, cause the normal lining to be replaced by a different cell type in a condition called Barrett’s esophagus. This condition significantly raises the risk of esophageal adenocarcinoma. A community-based study found that Barrett’s esophagus increases the risk of esophageal cancer roughly 10 times and the risk of esophageal adenocarcinoma specifically about 30 times compared to the general population.²⁵ A US cohort study estimated the risk increase at 10 to 55 times, depending on the population studied.²⁶

The same study found that reflux disease on its own, without Barrett’s, carried only a modestly increased risk of esophageal cancer.²⁵ This distinction matters because many people with chronic heartburn worry about cancer, and the honest answer is that their worry is mostly justified only if Barrett’s has already developed. Reflux itself is not harmless, but the cancer risk it carries without Barrett’s is small. People diagnosed with Barrett’s are typically placed on surveillance endoscopy schedules to watch for the early signs of cancerous change.

When Ulcers Are Caused by a Tumor

In rare cases, the ulcer is not a precursor to cancer or a bystander near cancer but a direct consequence of a tumor elsewhere. Zollinger-Ellison syndrome is a condition in which a tumor called a gastrinoma, usually in the pancreas or duodenum, produces massive amounts of the hormone gastrin. This drives the stomach to secrete extreme levels of acid, leading to severe and recurrent peptic ulcers, chronic diarrhea, and acid reflux.²⁷ The gastrinoma itself is a neuroendocrine tumor that can be benign or malignant.²⁸

Zollinger-Ellison syndrome is uncommon, but it illustrates an important clinical point: ulcers that keep coming back despite standard treatment, particularly if they appear in unusual locations or are accompanied by persistent diarrhea, should prompt investigation for an underlying hormonal cause. In these patients, the ulcers are a symptom of the tumor, not an independent disease.