Stomach cancer, also called gastric cancer, develops when abnormal cells in the lining of the stomach begin to grow out of control. It is one of the more common cancers worldwide, yet it often stays quiet in its early stages, when the symptoms can look like ordinary indigestion. Because of this, many cases are found later than doctors would like. Understanding how the disease starts, what raises your risk, and which warning signs deserve attention can help you act sooner and ask the right questions. This article explains what stomach cancer is, its main causes and symptoms, how it is diagnosed, where blood tests fit into the picture, and the treatments and recent research shaping care today.
What is stomach cancer?
The stomach is a muscular pouch in the upper abdomen that mixes food with acid and enzymes before passing it into the small intestine. Its inner wall is built from several layers, and the innermost layer, called the mucosa, is where most tumors begin. Stomach cancer forms when cells in this lining pick up changes in their DNA that let them multiply without the usual controls. Growth is often slow, and a tumor can develop over many years before it causes clear problems.
Doctors sometimes divide these tumors by where they start. Cancers at the top of the stomach, near where it meets the esophagus, can behave differently from those in the lower stomach. This location influences both the symptoms a person notices and the treatment that works best. Overall, stomach cancer has become less common in many countries over recent decades, partly because Helicobacter pylori infections are now found and treated more often, but it remains a serious disease that benefits from early attention.
Types of stomach cancer
According to the American Cancer Society, about 90 to 95 percent of stomach cancers are adenocarcinomas, meaning they start in the gland cells of the mucosa. Adenocarcinomas are often described as intestinal or diffuse, a distinction that reflects how the cells look and spread under a microscope. Less common forms include gastrointestinal stromal tumors (GISTs), neuroendocrine or carcinoid tumors, and lymphomas of the stomach. Because these types are treated differently, identifying the exact kind of cancer is an early and important step.
What causes stomach cancer, and who is at risk?
There is rarely a single cause. Instead, stomach cancer usually reflects a mix of factors that damage the stomach lining and change how its cells behave over time. Knowing these risk factors can help you and your doctor decide when closer attention is worth it.
Helicobacter pylori infection
The most important known risk factor is long-term infection with Helicobacter pylori, a common bacterium that lives in the stomach lining. Over years, it can cause ongoing inflammation, gradually pushing the lining toward precancerous changes. Most people who carry the bacterium never develop cancer, but its role is now well established, and clearing the infection removes one of the strongest preventable risks. A simple breath, stool, or blood test can detect it. Researchers describe a step-by-step process in which lasting inflammation first thins the lining, a change called atrophic gastritis, then leads to intestinal metaplasia, and occasionally moves further toward cancer. Finding and treating the infection early can interrupt this sequence before serious damage sets in.
Diet, smoking, and lifestyle
Diets heavy in salty, smoked, pickled, or processed foods and low in fresh fruit and vegetables are linked to higher risk. Smoking roughly raises the odds as well, and heavy alcohol use and excess body weight add to the picture. Long-standing acid reflux can also cause a nagging acid reflux cough, and reflux that reaches the top of the stomach is associated with cancers in that area.
Age, family history, and medical conditions
Risk rises with age, and most people diagnosed are over 60. Men are affected somewhat more often than women. Certain conditions, such as chronic gastritis, pernicious anemia, stomach polyps, or previous stomach surgery, also increase risk. A minority of cases run in families through inherited conditions such as hereditary diffuse gastric cancer, linked to changes in the CDH1 gene. If several close relatives have had stomach or related cancers, tell your doctor, who may suggest earlier or more frequent checks.
Symptoms and warning signs of stomach cancer
Early stomach cancer often causes no symptoms at all, or only vague ones that are easy to blame on something minor. As a tumor grows, more noticeable problems can appear. Common symptoms include:
- Persistent indigestion, heartburn, or discomfort in the upper abdomen
- Feeling full quickly, even after a small meal
- Nausea, or trouble swallowing that slowly gets worse
- Loss of appetite and unintended weight loss
- Ongoing tiredness, sometimes from anemia caused by slow blood loss
- Black, tarry stools, or vomiting that contains blood
These symptoms are far more often caused by harmless conditions such as an ulcer or an infection. Bleeding higher in the digestive tract usually turns stools black, while bleeding lower in the tract can instead produce pendarahan rektal. The point is not to worry over a single episode of indigestion, but to notice symptoms that persist or worsen.
Kapan harus menemui dokter?
Make an appointment if any of the following continue for more than two weeks, and seek prompt care if you notice signs of bleeding:
- Indigestion or stomach pain that does not settle with usual measures
- New difficulty swallowing, or food seeming to stick
- Unexplained weight loss or a lasting loss of appetite
- Feeling full after eating only a little, week after week
- Vomiting blood, or passing black, tarry stools
- Unusual tiredness, paleness, or breathlessness that could point to anemia
Seeing a doctor early does not mean you have cancer. Most people with these symptoms do not. But an early check is the best way to find and treat any serious cause while it is most manageable.
How stomach cancer is diagnosed
The main tool for diagnosis is an upper endoscopy, sometimes called a gastroscopy. A doctor passes a thin, flexible tube with a camera through the mouth to look directly at the stomach lining. If a suspicious area is seen, the doctor takes a small tissue sample, called a biopsy, so it can be examined under a microscope. Only a biopsy can confirm cancer and identify its type. If cancer is found, imaging such as a CT scan, an endoscopic ultrasound, or a PET scan helps show whether it has spread, a process known as metastasis. Staging uses a system that describes how deep the tumor has grown and whether it has reached nearby lymph nodes or distant organs, and an endoscopic ultrasound can show how far into the stomach wall a tumor extends. This staging guides treatment.
Where blood tests fit in
Blood tests cannot diagnose stomach cancer on their own. No blood test can confirm the disease, and a normal result does not rule it out. What blood work can do is support the wider picture: flagging a risk factor, hinting at hidden bleeding, or helping monitor a cancer that is already known. To look for hidden blood loss, doctors often order a hitung sel darah lengkap (CBC). Slow bleeding from a tumor can cause anemia defisiensi besi, and during follow-up doctors may track a blood tumor marker called carcinoembryonic antigen (CEA). In some digestive cancers, clinicians also measure the CA 19-9 blood marker. The table below shows how these tests help, and where they stop short.
| Tes darah | Apa yang dapat disarankan | Key limitation |
|---|---|---|
| H. pylori tests (breath, stool, or blood) | Detect infection with the main bacterial risk factor | A positive result signals infection to treat, not cancer |
| Hitung darah lengkap (CBC) | May reveal anemia caused by slow bleeding from a tumor | Anemia has many causes; a normal count does not rule cancer out |
| Iron studies, including ferritin | Can show iron deficiency from long-term blood loss | Non-specific; low iron is far more often benign |
| Tumor markers (CEA, CA 72-4, CA 19-9) | Sometimes used to monitor a known cancer or its treatment | Often normal early and raised by benign conditions; not a screening test |
How stomach cancer is treated
Treatment depends on the type of cancer, where it sits, how far it has spread, and a person’s overall health. Care is usually planned by a team that may include a surgeon, a medical oncologist, a radiation oncologist, a gastroenterologist, and a dietitian.
Surgery is the main treatment when the cancer is caught early enough to remove. Very early tumors confined to the lining can sometimes be taken out through an endoscope, without open surgery. More often, part or all of the stomach is removed in an operation called a gastrectomy, along with nearby lymph nodes. Chemotherapy may be given before surgery to shrink a tumor, or after it to lower the chance of return. Radiation therapy is used in some situations, often alongside chemotherapy.
For advanced disease, treatment focuses on controlling the cancer and easing symptoms. This is where newer targeted drugs and immunotherapy have changed the options in recent years, matched to the biology of each tumor. For some advanced cancers, a drug called ramucirumab, which limits the blood supply a tumor needs to grow, may be combined with chemotherapy. Clinical trials are also worth discussing, since they can offer access to newer approaches before they become widely available. Supportive care, including help with nutrition and pain, is an important part of treatment at every stage.
Latest scientific advances in stomach cancer
Research on stomach cancer has moved quickly, especially around prevention and treatments tailored to a tumor’s biology. Here is what recent, high-quality studies suggest, in plain terms.
Clearing H. pylori to lower risk
Large reviews published in 2023 confirmed that Helicobacter pylori is the single biggest preventable cause of stomach cancer, and that finding and clearing the infection can reduce long-term risk. What this means for you: a simple test can detect the bacterium, and a short course of antibiotics can clear it, removing a major risk factor before years of low-level damage build up. If you have had ulcers or a family history of stomach cancer, it is worth asking your doctor whether testing makes sense.
HER2-targeted smart drugs
Some stomach cancers carry extra copies of a protein called HER2 on their surface. A newer drug, trastuzumab deruxtecan, works like a guided delivery system: an antibody finds HER2 and carries a chemotherapy payload straight to those cells. In trials reported between 2023 and 2025, it helped shrink tumors in people whose cancer had grown after earlier treatment. What this means for you: if a biopsy shows a tumor is HER2-positive, more targeted choices exist than a few years ago, though doctors are still confirming the best way to use them.
Immunotherapy joins first-line care
Immunotherapy uses medicines that help the body’s own immune system recognize and attack cancer. Since 2023, expert guidelines from the American Society of Clinical Oncology have supported adding drugs such as nivolumab or pembrolizumab to chemotherapy for many advanced stomach cancers with certain markers. What this means for you: doctors increasingly test a tumor’s biology, for example a marker called PD-L1, to match each person with the therapy most likely to help.
A newer target called claudin 18.2
Scientists have found another target, called claudin 18.2, on the surface of many stomach-cancer cells. A drug named zolbetuximab attaches to this target and, combined with chemotherapy, has delayed the time before cancer worsens in people whose tumors carry it. What this means for you: testing a biopsy for claudin 18.2 is becoming one more way to personalize treatment, which is part of why the tissue sample taken during an endoscopy matters so much.
Reducing your risk and living with stomach cancer
You cannot change your age or your genes, but several everyday steps lower risk. Testing for and treating Helicobacter pylori is one of the most effective. The Mayo Clinic and other centers also advise eating plenty of fruit and vegetables, cutting back on salty and smoked foods, and not smoking. Note that in the United States, the National Cancer Institute states there is no standard screening test for stomach cancer for people at average risk, so paying attention to persistent symptoms remains important.
For those living with a diagnosis, good nutrition, regular follow-up, and emotional support all matter. After surgery, eating smaller and more frequent meals is often necessary, and a dietitian can help. Because part or all of the stomach may be removed, some people need vitamin B12 injections and other supplements over the long term, and regular check-ups help catch any return early. Follow-up visits may include blood tests to watch for anemia or to track tumor markers over time. Understanding what those numbers mean can make appointments feel less overwhelming and help you take an active part in your care.
Glosarium
| Ketentuan | Definisi |
|---|---|
| Gastric | Relating to the stomach. Gastric cancer is another name for stomach cancer. |
| Adenocarcinoma | Cancer that starts in gland cells of a lining, such as the stomach mucosa. It is the most common type of stomach cancer. |
| Helicobacter pylori | A common bacterium that can infect the stomach lining and, over time, raise the risk of ulcers and stomach cancer. |
| Endoscopy | A test using a thin, flexible camera passed through the mouth to view the stomach lining. Also called gastroscopy. |
| Biopsi | The removal of a small tissue sample so it can be examined under a microscope to confirm a diagnosis. |
| Penanda tumor | A substance measured in blood that can rise with some cancers. Used mainly for monitoring, not for diagnosis. |
| HER2 | A protein found in larger amounts on some cancer cells. HER2-positive tumors may respond to specific targeted drugs. |
| Claudin 18.2 | A protein on the surface of many stomach-cancer cells that newer targeted treatments are designed to find. |
| Imunoterapi | Treatment that helps the body’s own immune system recognize and attack cancer cells. |
| Metastasis | Penyebaran kanker dari tempat asalnya ke bagian tubuh lainnya. |
Pertanyaan yang sering diajukan
What are the early warning signs of stomach cancer?
Early stomach cancer often causes no symptoms, or only mild ones such as indigestion, mild nausea, or feeling full quickly. Because these overlap with far more common conditions, they are easy to overlook. Signs that deserve a doctor’s attention include symptoms that persist or worsen over weeks, unintended weight loss, new trouble swallowing, or any sign of bleeding such as black stools or vomiting blood. Noticing a pattern, rather than a single episode, is what matters most.
Can a blood test detect stomach cancer?
No single blood test can diagnose stomach cancer. Blood work can support the process, for example by revealing anemia from slow bleeding or by tracking tumor markers in someone already diagnosed, but it cannot confirm or rule out the disease. A diagnosis requires an endoscopy and a biopsy. Blood tests are most useful for spotting clues that prompt further testing and for monitoring during and after treatment.
What is the survival rate for stomach cancer?
Survival varies widely and depends heavily on the stage at diagnosis, the type of cancer, and how it responds to treatment. In general, stomach cancer found early, while it is still limited to the stomach, is more treatable than cancer that has already spread. Because early disease often causes few symptoms, many cases are found later, which is why paying attention to persistent symptoms is so important. Your care team can give figures that fit your individual situation.
Apakah kanker lambung bersifat turun-temurun?
Most stomach cancers are not inherited. However, a small share are linked to genetic conditions passed down in families, such as hereditary diffuse gastric cancer, which involves changes in the CDH1 gene. Having one relative with stomach cancer slightly raises risk; having several, or relatives diagnosed young, raises it more. If that describes your family, mention it to your doctor, who may recommend genetic counseling or earlier checks.
Bagaimana cara mendeteksi kanker lambung?
In the United States, there is no routine screening program for stomach cancer in people at average risk, according to the National Cancer Institute. In some countries where the disease is more common, endoscopy is used to screen. People at higher risk, for instance those with certain inherited conditions or precancerous changes, may be offered regular endoscopic checks. If you think you may be at higher risk, ask your doctor what monitoring is appropriate for you.
Are stomach cancer symptoms different in women?
The core symptoms of stomach cancer are broadly the same in women and men: indigestion, feeling full quickly, weight loss, nausea, and fatigue. Some symptoms, such as tiredness from anemia, may be blamed on other causes, which can delay attention. The guidance is the same regardless of sex: symptoms that persist, worsen, or involve bleeding should be checked by a doctor rather than waited out.
Sumber
- National Cancer Institute — What Is Stomach Cancer? cancer.gov/types/stomach
- American Cancer Society — Stomach Cancer (About, Types, Risk Factors, Detection, Treatment). cancer.org/cancer/types/stomach-cancer.html
- Mayo Clinic — Stomach cancer: Symptoms and causes. mayoclinic.org
- Thrift AP, Wenker TN, El-Serag HB — Global burden of gastric cancer: epidemiological trends, risk factors, screening and prevention — Nature Reviews Clinical Oncology, 2023. doi.org/10.1038/s41571-023-00747-0
- Malfertheiner P, et al. — Helicobacter pylori infection — Nature Reviews Disease Primers, 2023. doi.org/10.1038/s41572-023-00431-8
- Van Cutsem E, et al. — Trastuzumab deruxtecan in HER2-positive advanced gastric or gastroesophageal junction cancer (DESTINY-Gastric02) — The Lancet Oncology, 2023. doi.org/10.1016/S1470-2045(23)00215-2
- Trastuzumab Deruxtecan or Ramucirumab plus Paclitaxel in Gastric Cancer (DESTINY-Gastric04) — The New England Journal of Medicine, 2025. doi.org/10.1056/NEJMoa2503119
- Shah MA, et al. — Immunotherapy and Targeted Therapy for Advanced Gastroesophageal Cancer: ASCO Guideline — Journal of Clinical Oncology, 2023. doi.org/10.1200/JCO.22.02331
- Zolbetuximab-clzb: Targeting Claudin 18.2 in Advanced Gastric and Gastroesophageal Adenocarcinoma — Annals of Pharmacotherapy, 2025. doi.org/10.1177/10600280251342801
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Blood tests do not diagnose stomach cancer, but they play a real supporting role. An H. pylori test can flag a major risk factor to treat, a complete blood count can reveal anemia from slow bleeding, and tumor markers such as CEA can help monitor a cancer that is already known. AI DiagMe helps you understand what these results mean in plain language, so you can have a more informed conversation with your doctor. It does not diagnose disease and does not replace medical advice.
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