Stomach Cancer: Symptoms, Causes & Treatment Options

What Is Stomach Cancer?

Stomach cancer (gastric cancer) is a malignant tumor that develops in the lining of the stomach. The most common type, adenocarcinoma, accounts for 90-95% of cases and originates in the glandular cells that produce stomach mucus. Stomach cancer is the fifth most common cancer worldwide, with approximately 1 million new cases diagnosed annually.

The stomach is a muscular, J-shaped organ located in the upper abdomen between the esophagus and small intestine. It plays a crucial role in digestion by storing food, mixing it with digestive enzymes, and gradually releasing it into the small intestine. The stomach wall consists of several layers, and cancer most commonly begins in the innermost layer called the mucosa, which contains glandular cells that produce digestive juices and protective mucus.

Stomach cancer develops when normal cells in the stomach lining undergo genetic changes (mutations) that cause them to grow and divide uncontrollably. Over time, these abnormal cells accumulate and form a tumor. Unlike benign tumors, malignant tumors can invade nearby tissues and spread (metastasize) to other parts of the body through the bloodstream or lymphatic system. This process typically occurs gradually over many years, which is why stomach cancer is more common in older adults.

The global incidence of stomach cancer varies significantly by geographic region. Rates are particularly high in East Asia (Japan, South Korea, China), Eastern Europe, and parts of Central and South America. These regional differences are attributed to variations in diet, prevalence of H. pylori infection, and other environmental factors. In Western countries, the incidence of stomach cancer has been declining over the past several decades, likely due to improved food preservation methods, decreased H. pylori infection rates, and reduced consumption of salted and smoked foods.

Types of Stomach Cancer

While adenocarcinoma is by far the most common type of stomach cancer, several other types exist:

• Adenocarcinoma: Accounts for 90-95% of all stomach cancers. Develops from the glandular cells in the stomach lining that produce mucus and digestive fluids.
• Lymphoma: Cancer that starts in the immune system cells (lymphocytes) in the stomach wall. Represents about 4% of stomach cancers.
• Gastrointestinal stromal tumors (GIST): Rare tumors that develop from special cells in the stomach wall called interstitial cells of Cajal. These tumors may be benign or malignant.
• Carcinoid tumors: Slow-growing tumors that start in the hormone-producing cells of the stomach. These are uncommon.
• Squamous cell carcinoma and small cell carcinoma: Very rare types that are treated similarly to adenocarcinoma.

Stages of Stomach Cancer

Cancer staging describes how far the disease has spread. Stomach cancer is staged from 0 to IV, with higher numbers indicating more advanced disease:

Stage 0 (Carcinoma in situ): Abnormal cells are present only in the innermost layer of the stomach lining. This is the earliest stage and is highly curable with surgery.

Stage I: Cancer has grown into deeper layers of the stomach wall but has not spread to lymph nodes or distant sites. Subdivided into IA (mucosa or submucosa only) and IB (into the muscle layer or 1-2 lymph nodes).

Stage II: Cancer has spread to the deeper muscle layers of the stomach wall and possibly to nearby lymph nodes, but not to distant organs.

Stage III: Cancer has grown through the stomach wall into nearby structures or has spread to many lymph nodes. It may involve the spleen, colon, liver, pancreas, or other nearby organs.

Stage IV: Cancer has spread to distant parts of the body (metastasis), such as the liver, lungs, peritoneum (abdominal lining), or distant lymph nodes. This is the most advanced stage.

What Are the Symptoms of Stomach Cancer?

Early stomach cancer often causes no symptoms or only vague symptoms like indigestion, mild stomach discomfort, and feeling full quickly when eating. As the disease progresses, symptoms may include unexplained weight loss, persistent nausea and vomiting, blood in the stool (appearing dark or black), loss of appetite, and fatigue. Because early symptoms are subtle, stomach cancer is often not detected until later stages.

One of the challenges with stomach cancer is that early-stage disease typically produces no symptoms or only mild, nonspecific symptoms that are easily attributed to other, more common conditions. This is a significant reason why stomach cancer is often diagnosed at advanced stages in countries without routine screening programs. Understanding the potential warning signs is crucial for seeking timely medical evaluation.

The symptoms of stomach cancer develop as the tumor grows larger and begins to affect the stomach's normal function. A tumor may interfere with the stomach's ability to store food, produce digestive enzymes, or move food into the small intestine. Advanced tumors can cause bleeding, obstruction, or spread to other organs, leading to additional symptoms.

Common Early Symptoms

In the early stages, stomach cancer may cause:

• Persistent indigestion or heartburn: A burning sensation or discomfort in the upper abdomen that doesn't improve with antacids
• Mild abdominal discomfort or pain: Vague discomfort or aching in the stomach area, often after eating
• Early satiety: Feeling full after eating only a small amount of food
• Slight nausea: Occasional queasiness, especially after meals
• Loss of appetite: Decreased interest in food or aversion to certain foods, particularly meat

These symptoms are common to many digestive conditions, including gastritis, peptic ulcers, and dyspepsia (sensitive stomach). However, if they persist for more than a few weeks or worsen over time, medical evaluation is warranted.

Advanced Symptoms

As stomach cancer progresses, symptoms become more pronounced:

• Unexplained weight loss: Losing weight without trying, often due to decreased appetite and difficulty eating
• Persistent vomiting: Especially if it contains blood or material that looks like coffee grounds
• Blood in the stool: Stools may appear dark, tarry, or black (melena) due to digested blood from the stomach
• Difficulty swallowing: If the tumor is near the junction of the esophagus and stomach
• Abdominal swelling: May occur if fluid accumulates in the abdomen (ascites)
• Severe fatigue: Often due to anemia from chronic blood loss
• Jaundice: Yellowing of the skin and eyes if cancer spreads to the liver

When Should You Seek Medical Care?

Contact your healthcare provider if you have persistent indigestion, unexplained weight loss, or loss of appetite lasting more than 3 weeks. Seek urgent care for black or bloody stools, vomiting blood or material resembling coffee grounds, or sudden severe abdominal pain. Call emergency services immediately if you have severe abdominal pain with dizziness, fainting, or feel extremely unwell.

Many of the symptoms associated with stomach cancer are common to other digestive conditions and often resolve on their own or with simple treatment. However, certain patterns of symptoms warrant medical evaluation to rule out serious conditions, including cancer.

Contact your healthcare provider if you experience any of the following:

• Persistent indigestion or stomach discomfort that doesn't improve with over-the-counter medications
• Unexplained weight loss, especially if you're losing weight without trying
• Loss of appetite or feeling full after eating small amounts for more than 3 weeks
• Persistent nausea or vomiting
• Increasing difficulty swallowing

Seek urgent medical attention (same day or next day) for:

• Black, tarry stools (melena), which may indicate bleeding in the stomach
• Vomiting that contains blood or looks like coffee grounds
• Significant unexplained weight loss (more than 5% of body weight)
• New-onset feeling of fullness lasting more than 3 weeks

What Causes Stomach Cancer?

The exact cause of stomach cancer is not fully understood, but several factors increase risk. Helicobacter pylori (H. pylori) bacterial infection is the most significant risk factor, causing chronic inflammation that can lead to cancer. Other risk factors include smoking, diet high in salted/smoked foods, family history, and certain genetic conditions. About 10% of cases may have an inherited component.

Stomach cancer develops when normal cells in the stomach lining acquire genetic mutations that cause uncontrolled growth. This process typically occurs gradually over many years, during which normal cells may pass through stages of precancerous changes before becoming cancerous. Understanding the risk factors can help identify individuals who may benefit from closer monitoring or lifestyle modifications.

Helicobacter pylori Infection

H. pylori is a spiral-shaped bacterium that infects the stomach lining and is recognized by the World Health Organization as a Group 1 carcinogen for stomach cancer. This common infection affects approximately half of the world's population, though most infected individuals never develop cancer. H. pylori causes chronic inflammation (gastritis) that, in some people, progresses through stages of atrophic gastritis, intestinal metaplasia, and dysplasia before potentially becoming cancerous.

The bacteria's ability to cause cancer is influenced by the bacterial strain, duration of infection, host genetic factors, and environmental factors like diet and smoking. H. pylori infection is also the primary cause of peptic ulcers, though most people with the infection experience no symptoms.

Dietary Factors

Diet plays an important role in stomach cancer risk:

• High-risk foods: Diets high in salted, smoked, and pickled foods are associated with increased risk. These preservation methods can create carcinogenic compounds (like N-nitroso compounds) and may damage the stomach lining.
• Protective foods: Diets rich in fresh fruits and vegetables appear to reduce risk, likely due to their antioxidant content and other protective compounds.
• Processed meats: Regular consumption of processed meats has been linked to increased stomach cancer risk.

Lifestyle Factors

Smoking: Tobacco use significantly increases stomach cancer risk, particularly for cancers in the upper part of the stomach near the esophagus. The risk increases with the amount and duration of smoking and decreases after quitting.

Alcohol: Heavy alcohol consumption may increase stomach cancer risk, though the evidence is less clear than for smoking.

Obesity: Being significantly overweight increases the risk of cancers at the junction between the esophagus and stomach (gastroesophageal junction cancers).

Genetic and Hereditary Factors

Approximately 10% of stomach cancer cases have a hereditary component:

• Family history: Having a first-degree relative (parent, sibling, or child) with stomach cancer increases your risk 2-3 fold.
• Hereditary diffuse gastric cancer (HDGC): A rare inherited syndrome caused by CDH1 gene mutations that dramatically increases stomach cancer risk.
• Lynch syndrome: An inherited condition that increases risk of several cancers, including stomach cancer.
• Other genetic syndromes: Familial adenomatous polyposis (FAP), Li-Fraumeni syndrome, and Peutz-Jeghers syndrome are associated with increased stomach cancer risk.

Other Risk Factors

• Age: Risk increases significantly after age 50, with most cases occurring in people over 70.
• Sex: Men are about twice as likely as women to develop stomach cancer.
• Previous stomach surgery: Partial gastrectomy for ulcer disease increases long-term cancer risk.
• Pernicious anemia: This condition affects vitamin B12 absorption and is associated with increased risk.
• Blood type A: People with blood type A have a slightly higher risk for unknown reasons.

How Is Stomach Cancer Diagnosed?

Stomach cancer is typically diagnosed through gastroscopy (upper endoscopy), where a flexible tube with a camera is inserted through the mouth to examine the stomach and obtain tissue samples (biopsy) for analysis. Additional tests including CT scans, blood tests, and sometimes laparoscopy are used to determine the cancer stage. The diagnostic process usually follows a standardized pathway to ensure timely evaluation.

If you have symptoms that suggest stomach cancer, your healthcare provider will conduct a thorough evaluation. The diagnostic process involves several steps to confirm whether cancer is present and, if so, determine its extent (staging). Accurate staging is essential for planning the most effective treatment.

Initial Evaluation

Your doctor will begin with a detailed medical history and physical examination. You'll be asked about your symptoms, how long you've had them, your family history of cancer, and any risk factors. The physical exam may include feeling your abdomen for any masses or enlarged organs, though early stomach cancers rarely produce findings on physical examination.

Blood tests may reveal:

• Anemia (low red blood cell count), which may indicate chronic bleeding
• Liver function abnormalities if cancer has spread to the liver
• Tumor markers like CEA or CA 19-9, though these are not specific for stomach cancer

Gastroscopy (Upper Endoscopy)

Gastroscopy is the gold standard for diagnosing stomach cancer. During this procedure:

• A thin, flexible tube with a camera (endoscope) is passed through your mouth, down the esophagus, and into the stomach
• The doctor can directly visualize the stomach lining and identify any abnormal areas
• Tissue samples (biopsies) are taken from suspicious areas for laboratory analysis
• The procedure is usually done under sedation and takes about 15-30 minutes

The biopsy samples are examined by a pathologist who can confirm whether cancer cells are present and determine the cancer type. If adenocarcinoma is confirmed, additional tests may be performed on the tissue to identify specific characteristics that may affect treatment decisions, such as HER2 status or microsatellite instability (MSI).

Staging Investigations

If cancer is confirmed, additional tests are performed to determine the stage:

CT scan (Computed Tomography): A CT scan of the chest, abdomen, and pelvis provides detailed images that can show the size and location of the tumor, whether lymph nodes are enlarged, and whether cancer has spread to distant organs like the liver or lungs.

Endoscopic ultrasound (EUS): An ultrasound probe attached to an endoscope can show how deeply the tumor has grown into the stomach wall and whether nearby lymph nodes appear abnormal.

PET scan (Positron Emission Tomography): May be used to detect cancer spread that isn't visible on CT scans, though not always necessary.

Laparoscopy: In some cases, particularly for potentially curable cancers, a small surgical procedure may be performed to look directly at the abdominal cavity. This can detect small deposits of cancer on the peritoneum or liver surface that may not be visible on imaging.

How Is Stomach Cancer Treated?

Treatment for stomach cancer depends on the stage and typically involves surgery (partial or total gastrectomy) combined with chemotherapy. Early-stage cancers may be cured with surgery alone, while more advanced cancers usually require chemotherapy before and/or after surgery. For cancers that cannot be surgically removed, treatments focus on controlling growth and managing symptoms through chemotherapy, radiation, targeted therapy, or immunotherapy.

The treatment plan for stomach cancer is developed by a multidisciplinary team of specialists including surgeons, medical oncologists, radiation oncologists, gastroenterologists, and other healthcare professionals. The best treatment approach depends on several factors, including the cancer stage, tumor location, your overall health, and your personal preferences.

Surgery

Surgery is the primary treatment for potentially curable stomach cancer. The goal is to remove the tumor with adequate margins of healthy tissue, along with nearby lymph nodes.

Partial (subtotal) gastrectomy: If the tumor is in the lower part of the stomach, the surgeon may remove only the portion containing the cancer. The remaining stomach is then connected to the small intestine.

Total gastrectomy: If the tumor involves the upper stomach or is widespread, the entire stomach may need to be removed. The esophagus is then connected directly to the small intestine. While this is a major change, people can live well without a stomach by eating smaller, more frequent meals.

Lymph node removal: During surgery, lymph nodes near the stomach are removed and examined to determine if cancer has spread. The extent of lymph node removal varies by surgical technique and is an important factor in determining prognosis.

Surgery is typically performed using either open technique (a larger incision) or minimally invasive approaches (laparoscopic or robotic surgery). The best approach depends on the tumor's size and location, and your surgeon's expertise.

Chemotherapy

Chemotherapy uses drugs to kill cancer cells throughout the body. For stomach cancer, chemotherapy is often used:

Before surgery (neoadjuvant): Chemotherapy given before surgery can shrink the tumor, making it easier to remove completely. This approach may also eliminate microscopic cancer cells that have spread beyond the stomach.

After surgery (adjuvant): Chemotherapy after surgery aims to kill any remaining cancer cells and reduce the risk of recurrence. Most patients with stage II or III stomach cancer receive both neoadjuvant and adjuvant chemotherapy.

For advanced cancer: When surgery is not possible, chemotherapy can help control cancer growth and relieve symptoms. Multiple chemotherapy drugs are typically combined for better effectiveness.

Common side effects of chemotherapy include nausea, fatigue, hair loss, mouth sores, and increased infection risk. Most side effects are temporary and can be managed with supportive medications.

Radiation Therapy

Radiation therapy uses high-energy beams to kill cancer cells. For stomach cancer, it may be used:

• Combined with chemotherapy after surgery (chemoradiation) in certain cases
• To relieve symptoms like pain or bleeding in advanced cancer
• As part of treatment when surgery is not possible

Targeted Therapy

Targeted therapies are drugs that attack specific features of cancer cells:

• HER2-targeted therapy: About 20% of stomach cancers have extra copies of the HER2 gene. Trastuzumab (Herceptin) targets HER2-positive cancers and is often combined with chemotherapy.
• Anti-angiogenic drugs: Ramucirumab blocks the formation of new blood vessels that tumors need to grow.

Immunotherapy

Immunotherapy helps your immune system recognize and attack cancer cells. Checkpoint inhibitors like pembrolizumab (Keytruda) and nivolumab (Opdivo) may be used for advanced stomach cancer, particularly for tumors with specific characteristics (MSI-high or PD-L1 positive).

Palliative Treatment

If stomach cancer cannot be cured, treatment focuses on maintaining quality of life and managing symptoms:

• Stent placement: If the tumor is blocking food from passing through, a metal tube (stent) can be placed to keep the passage open.
• Pain management: Various medications and techniques can effectively control cancer-related pain.
• Nutritional support: Feeding tubes or intravenous nutrition may help maintain nutrition when eating is difficult.
• Palliative chemotherapy: Can slow tumor growth and improve symptoms even when cure is not possible.

How Does Stomach Cancer Affect Daily Life?

Living with or after stomach cancer treatment involves significant adjustments, particularly regarding eating. After stomach surgery, you'll need to eat smaller, more frequent meals and may experience dumping syndrome (rapid passage of food causing discomfort). Vitamin B12 supplementation is required for life after total gastrectomy. Physical activity aids recovery, and most people need several months of sick leave. Emotional support and rehabilitation services are important parts of recovery.

A diagnosis of stomach cancer affects many aspects of life, from physical functioning to emotional well-being. Understanding what to expect and accessing appropriate support can help you cope with these changes and maintain the best possible quality of life.

Eating After Stomach Surgery

After partial or total gastrectomy, your digestive system must adapt to working with a smaller stomach or no stomach at all. Most people can eventually eat regular food, but the way they eat must change:

• Smaller, more frequent meals: Instead of three large meals, you'll need to eat 5-8 small meals throughout the day.
• Chew thoroughly: Take time to chew food well and eat slowly.
• Limit liquids with meals: Drinking too much liquid while eating can cause discomfort.
• Avoid certain foods: Very sweet or fatty foods may cause problems initially.

Dumping syndrome is a common experience after stomach surgery. It occurs when food moves too quickly into the small intestine, causing symptoms like nausea, sweating, cramping, and feeling faint after eating. Learning to recognize triggers and adjusting eating habits usually controls this problem. Symptoms typically improve over time as your body adapts.

Nutritional considerations: Maintaining adequate nutrition can be challenging after stomach surgery. Working with a dietitian is essential. You may need:

• Vitamin B12 supplementation (required for life after total gastrectomy, as the stomach is needed to absorb this vitamin)
• Iron and calcium supplements
• Oral nutritional supplements if you're not getting enough calories
• Nutritional tube feeding through the small intestine (jejunostomy tube) temporarily after surgery

Physical Recovery

Recovery from stomach cancer treatment is gradual and varies by individual:

• Fatigue: Tiredness is common during and after treatment. It may be caused by the cancer itself, treatment side effects, anemia, or emotional stress. Pace yourself and allow time for rest.
• Physical activity: Gentle exercise like walking helps recovery. Gradually increase activity as you feel able. Physical therapy may help restore strength and function.
• Work: Most people need several months off work after major stomach surgery. The timing of return depends on the type of work and how recovery progresses.

Emotional and Psychological Support

A cancer diagnosis brings significant emotional challenges. Feelings of fear, anxiety, sadness, and uncertainty are normal. Support is available through:

• Cancer nurse specialists and counselors at your treatment center
• Patient support groups where you can connect with others facing similar challenges
• Mental health professionals experienced in helping cancer patients
• Family and friends who can provide practical and emotional support

Follow-Up Care

After completing treatment, you'll have regular follow-up appointments to monitor for recurrence and manage any ongoing effects of treatment. Follow-up typically includes:

• Physical examinations
• Blood tests
• CT scans or other imaging at intervals
• Endoscopy in some cases
• Monitoring of nutritional status and vitamin levels

Where Can You Find Support and Information?

Support is available through your healthcare team, cancer support organizations, and patient advocacy groups. Contact nurses, also called nurse navigators or clinical nurse specialists, can provide ongoing guidance and help coordinate your care. Cancer support groups offer opportunities to connect with others facing similar challenges. Children of parents with cancer have a right to age-appropriate information and support.

Receiving a cancer diagnosis can feel overwhelming, and you don't have to face it alone. Multiple sources of support are available to help you through diagnosis, treatment, and recovery.

Your Healthcare Team

Your treatment center has professionals dedicated to supporting patients:

• Contact nurse/nurse navigator: A specialized nurse who serves as your point of contact, answers questions, and helps coordinate your care.
• Oncology social worker: Can help with practical concerns, emotional support, and connecting you with resources.
• Dietitian: Essential for helping manage eating challenges after stomach surgery.
• Palliative care team: Focuses on quality of life and symptom management for people with serious illness, regardless of stage.

Support Organizations

Various organizations provide information, support services, and community connections for people affected by stomach cancer. Cancer support organizations can offer:

• Educational materials about stomach cancer and treatment
• Support groups (in-person and online)
• One-on-one peer support from others who have faced stomach cancer
• Information about clinical trials
• Practical assistance programs

Supporting Children

If you have minor children, they have a right to information and support appropriate to their age and understanding. Healthcare teams can help you:

• Decide how to talk to children about your diagnosis
• Provide age-appropriate explanations
• Connect with resources for children of parents with cancer
• Identify signs that children may need additional support

For Caregivers and Family Members

Caring for someone with cancer is challenging. Caregivers also need support:

• Don't hesitate to ask the healthcare team questions
• Seek support for your own emotional needs
• Accept help from others when offered
• Take breaks when possible to maintain your own health