Stomach cancer often presents itself as a silent disease, with no pain, no drama, until it's too late. That's why it's crucial to recognize those early signs that our body is sending us, even though we may easily mistake them for something entirely ordinary, like indigestion or stress.

How common is stomach cancer?

Stomach cancer is less common than, for example, lung or breast cancer, but still quite dangerous. According to the World Health Organization (WHO) data from 2022, more than 1 million people worldwide are diagnosed with this form of cancer each year, and almost 800,000 die from it. In Slovenia, according to the data from the Oncology Institute Ljubljana, around 400 new cases of stomach cancer are diagnosed each year, with more than 60% affecting men.

For comparison: in life, 1 in 111 people will develop stomach cancer, meaning that almost everyone knows someone who has had this disease.

Not always inherited

Stomach cancer is not as frequently inherited as we might think. Only about 5–10% of cases are genetic. Most people develop it due to so-called sporadic mutations, meaning that errors occur in certain cells of the stomach lining without anyone "bringing" them into the family. Among the main triggers are: a diet high in salt and smoked foods, long-term infection with Helicobacter pylori (a bacterium that lives in the stomach), smoking, and excessive alcohol consumption.

But now, to the essence – which symptoms can indicate stomach cancer, even if you don't feel any pain?

1. Blood in the stool or vomit
   This is one of the more reliable signs that something is seriously wrong in the digestive system. Blood in the stool is not always bright red – sometimes it's almost black, indicating it's old and digested. This can be a sign of bleeding higher up in the digestive tract, perhaps even in the stomach. If there is blood in vomit, it's often dark and looks like coffee grounds. This is not a normal occurrence – and never delay seeing a doctor!
   
   Interesting: In a study in Japan (where stomach cancer is most common in the world), they found that 72% of patients with gastrointestinal bleeding also had abnormalities in the gastric mucosa, often associated with early-stage cancer.
   
   
2. Sudden loss of appetite
   Were you a big eater recently but now feel no desire to eat after just three bites? And this happens repeatedly? This is one of the signs that is often overlooked. People think it's "psychological", a result of stress, but it could actually be something much more serious. Stomach cancer can cause the mucosa to tense, causing the stomach to fill up faster and the body to feel full too quickly. In medicine, this is called early satiety.
   
   According to the Mayo Clinic, 60% of stomach cancer patients report this symptom in the early stages of the disease – before more severe complications occur.
   
   
3. Pain in the upper abdomen (but not always)
   Yes, pain can indicate cancer – but it's rare. In fact, many people with stomach cancer experience no pain in the early stages. However, if pain does occur, it's not usual. It's not like the "poking in the stomach" feeling you get after eating a pizza with peppers. It's a persistent, dull pain that doesn't go away for days or weeks. People often mistake it for an ulcer or gastritis. Sometimes it occurs after eating and can radiate to the back.
   
   
4. Unexplained weight loss
   Losing weight without dieting, exercise, or any effort can be a sinister sign. If you lose more than 5% of your body weight in one month and don't know why, it could be a serious health alarm. For example, if you weigh 80 kg and lose more than 4 kg in a month for no reason, that's something you should investigate.
   
   According to the National Cancer Institute (NIH), unexplained weight loss is the second most common symptom in patients with stomach cancer, right after loss of appetite.
   
   
5. Heartburn, belching, bad breath
   Heartburn is not always just a result of a greasy meal or lack of sleep. If it lasts for weeks, occurs after every meal, is accompanied by a feeling of heaviness and belching, it could be due to changes in the gastric mucosa. Cancer often changes the acidic environment in the stomach, leading to poor digestion, a feeling of acidity in the mouth, and bad breath that doesn't go away even with chewing gum.
   
   In a study on 320 stomach cancer patients at the Charite Clinic in Berlin, persistent heartburn was detected in 47% of patients at least six months before the diagnosis was made.
   
   
6. Bloating, diarrhea, constipation
   When something is wrong in the abdominal cavity, the body often responds with a very precise mechanism – it alters digestion. Stomach cancer can press on the intestines, slow down food emptying, or change the balance of bacteria. This leads to frequent alternating between diarrhea and constipation, bloating after every meal, flatulence, and even cramps.
   
   According to gastroenterologist Dr. Maja Strmole, patients showing sudden changes in their digestive rhythm should be referred for gastroscopy, as these could be the first signs of stomach changes, including cancer.
   Listen to your body before it screams
   
   Stomach cancer is insidious. It may not necessarily hurt. It may not necessarily be obvious. But it can hide behind everyday things – a slightly reduced appetite, sudden weight loss, more frequent heartburn. If you notice multiple signs together, don't wait. It costs nothing to get checked – and it might save your life.
   
   As a medical researcher from Korea, Dr. Jae-Hyun Kim, once said: Every cancer is easier to treat when detected early. Stomach cancer is no exception. Silent symptoms require loud attention.
   
   And one more thing: according to the European Cancer Patient Coalition, the five-year survival rate for stomach cancer increases from 15% to over 60% when the disease is detected early. Therefore, it's worth listening to your body, asking your doctor, and taking timely action.