Do antacids have a link to stomach cancer?

Long-term use of medications for heartburn and acid reflux has long raised concerns about a possible link to an increased risk of stomach cancer . However, a large population study published in the British Medical Journal (BMJ) offers a more nuanced perspective, suggesting that this association may not exist when adjusting for confounding and methodological factors.

The study , which included national health data from five Northern European countries, concluded that long-term use of acid medications known as proton pump inhibitors is not associated with an increased risk of developing adenocarcinoma, a type of stomach cancer.

The study came to address methodological gaps that marred previous research linking these drugs to stomach cancer, such as short follow-up periods, weak statistical power, accounting for drug use prior to cancer diagnosis, and failure to control for key factors such as Helicobacter pylori infection.

Because of the difficulty of conducting long-term, randomized controlled trials in this field, the researchers adopted a robust observational design that takes these limitations into account.

The study, which covered the period from 1994 to 2020 (16 years) within a research project known as “NordGETS”, was conducted using high-quality, complete national registries in 5 Scandinavian countries: Denmark, Finland, Iceland, Norway, and Sweden, and included:

• 17,232 cases of stomach cancer.
• 172,297 uninfected individuals were randomly selected from the general population. The two groups were matched for age, gender, year of age, and country.

The results showed that : 10.2% of stomach cancer cases used proton pump inhibitors long-term, compared to 9.5% in the non-affected group.

After adjusting for multiple factors, including Helicobacter pylori infection, stomach ulcers, smoking, alcohol, obesity, type 2 diabetes, and certain other medications, no statistically significant association was found between long-term use of proton pump inhibitors and the risk of developing stomach cancer.

No similar association was recorded among users of histamine-2 receptor antagonists, which strengthened the reliability of the results.

Why was a type of stomach cancer ruled out?

The researchers ruled out stomach cancer near the heart to avoid confusion with gastroesophageal reflux disease, the main reason for prescribing proton pump inhibitors.

Because the assumed biological mechanisms of action of these drugs do not apply to this type of cancer, the study identified several reasons that may explain the false-positive results in previous research, including:

• Calculating the use of medication prior to cancer diagnosis.
• Include short-term use.
• Failure to differentiate between types of stomach cancer.
• Lack of adequate control of factors associated with Helicobacter pylori.

What do the results mean for patients?

These results provide important reassurance to the millions of patients who rely on proton pump inhibitors for extended periods when there is a clear medical need, as they indicate that long-term use does not appear to increase the risk of stomach cancer when systematically and carefully assessed.

However, researchers stress the importance of rational use and not taking these drugs for extended periods without medical supervision, given other potential side effects unrelated to cancer.

The study indicates that proton pump inhibitors are not associated with an increased risk of stomach cancer with long-term use, provided confounding factors are carefully controlled. It also emphasizes the importance of prescribing these medications according to medical guidelines, with periodic assessments of their continued necessity.