Stomach cancer is one of the most dangerous oncological diseases, ranking fourth among cancer deaths worldwide. Its main characteristic is that its symptoms often resemble those of less severe disorders, which is why diagnosis is usually made too late, after the tumor has spread.

This disease, also known as gastric cancer, develops from cells lining the stomach.

The main symptoms of stomach cancer are:

Upper abdominal pain is often aching and constant.

Sudden weight loss without apparent cause.

Loss of appetite and aversion to meat products.

Nausea and vomiting, sometimes with blood.

A rapid feeling of fullness even after a small amount of food.

Fatigue and weakness caused by anemia.

Blood in the stool—stool becomes dark or black.

However, according to a new study by researchers from Rutgers Robert Wood Johnson School of Medicine (New Jersey, USA), the first signs of stomach cancer can be detected long before symptoms appear—using a simple mouth rinse.

The researchers used a simple “swish and spit” procedure and identified characteristic changes in the composition of oral bacteria in people who subsequently developed stomach cancer.

According to Dr. Shruti Reddy Perati, the study’s author, there is a close relationship between the microflora of the mouth and stomach:

“By understanding the bacteria present in the mouth, we can assess the health of the stomach. This is an important discovery that could change approaches to early diagnosis and cancer prevention.”

As part of the study, the researchers analyzed oral microflora samples from 98 patients undergoing endoscopy. Among them were:

38 healthy participants,

30 patients diagnosed with stomach cancer,

30 people with precancerous changes in the gastric mucosa (inflammation, atrophy, etc.).

Although not all people with such changes develop cancer, statistics show that approximately one in 50 patients with chronic inflammation of the gastric mucosa develops cancer over 20 years.

The scientists discovered significant differences in the oral microbiome composition between healthy participants and patients with cancer or precancerous conditions. Moreover, samples from the latter two groups were very similar, suggesting the possibility of detecting pathological changes at the preclinical stage.

The researchers identified 13 bacterial species that showed the most significant difference between the groups. Rothia, Leptotrichia, and Lactobacillus were more common in patients with stomach cancer, which may serve as a biomarker for non-invasive diagnosis of the disease.