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Gastric Cancer – Comprehensive Medical Guide

Overview

Gastric cancer, also called stomach cancer, is a malignant tumor that originates in the lining of the stomach. It usually begins in the glandular cells that produce mucus and digestive juices, but less commonly it can arise from other cell types (e.g., neuroendocrine cells).

Worldwide, gastric cancer is the fifth most common cancer and the third leading cause of cancer‑related death. In 2022, the WHO reported approximately 1.09 million new cases and 770,000 deaths globally. The disease is more prevalent in East Asia (especially Japan, South Korea, and China), Eastern Europe, and parts of Central and South America.

Age and gender matter: most patients are diagnosed after the age of 55, and men are about twice as likely to develop gastric cancer as women. However, it can occur at any age, including in children with hereditary cancer syndromes.

Symptoms

Early gastric cancer often produces no noticeable signs, which is why routine screening is important in high‑risk regions. When symptoms do appear, they can be vague and overlap with benign gastrointestinal conditions. Below is a comprehensive list with brief explanations.

• Persistent indigestion or heartburn – a feeling of burning or discomfort in the upper abdomen that does not improve with antacids.
• Upper abdominal pain or discomfort – dull, gnawing pain that may worsen after meals.
• Early satiety – feeling full after eating only a small amount of food.
• Unintentional weight loss – loss of >5% body weight over a few weeks without trying.
• Nausea and vomiting – may be intermittent; if vomiting contains blood (hematemesis) it signifies bleeding.
• Loss of appetite – reduced desire to eat, often related to early satiety.
• Vomiting of undigested food – especially if it occurs soon after eating.
• Difficulty swallowing (dysphagia) – occurs when the tumor obstructs the gastro‑esophageal junction.
• Gastrointestinal bleeding – manifests as black, tar‑like stools (melena) or bright red blood in stool.
• Fatigue or weakness – frequently caused by anemia from chronic bleeding.
• Feeling of bloating or distention – can be a sign of tumor causing partial obstruction.
• Persistent hiccups – rarely, diaphragmatic irritation from a large tumor.

If any of these symptoms persist for more than a few weeks, especially in someone over 50 or with known risk factors, a medical evaluation is warranted.

Causes and Risk Factors

Primary Causes

Gastric cancer is multifactorial. The disease arises when normal stomach cells acquire genetic mutations that lead to uncontrolled growth. These mutations can be triggered by environmental exposures, infections, dietary habits, and inherited genetic syndromes.

Major Risk Factors

• Helicobacter pylori infection – the single most important modifiable risk factor; chronic infection causes atrophic gastritis and intestinal metaplasia. Eradication reduces cancer risk by ~30‑40% (NIH).
• Dietary factors – high intake of smoked, salted, or pickled foods; low consumption of fresh fruits and vegetables; excessive alcohol.
• Tobacco use – smokers have a 1.5‑ to 2‑fold higher risk; risk decreases after quitting.
• Family history & hereditary syndromes – first‑degree relatives with gastric cancer double the risk; genetic conditions such as hereditary diffuse gastric cancer (CDH1 mutation), Lynch syndrome, and familial adenomatous polyposis increase susceptibility.
• Previous stomach surgery – partial gastrectomy for ulcer disease can alter gastric environment and increase risk.
• Obesity – especially central obesity, is linked to increased risk of gastroesophageal junction adenocarcinoma.
• Age & gender – risk rises sharply after age 55; men are about twice as likely to develop the disease.
• Blood type – some studies suggest type A may carry a modestly higher risk.
• Occupational exposures – workers in coal mining, rubber, or metal may have higher incidence.

Diagnosis

Because early disease is often silent, diagnosis usually occurs when symptoms prompt evaluation. A systematic approach combines endoscopic visualization, imaging, and laboratory tests.

Initial Evaluation

• Physical examination – may reveal palpable abdominal mass, lymphadenopathy, or signs of anemia.
• Blood tests – complete blood count (CBC) for anemia, liver function tests, serum electrolytes; tumor markers (CEA, CA 19‑9) are not diagnostic but can aid monitoring.

Endoscopic Procedures

• Upper gastrointestinal (GI) endoscopy (esophagogastroduodenoscopy, EGD) – gold standard. Allows direct visualization of the mucosa, biopsy of suspicious lesions, and sometimes therapeutic interventions (e.g., hemostasis).
• Endoscopic ultrasound (EUS) – assesses depth of tumor invasion (T stage) and samples nearby lymph nodes (fine‑needle aspiration).

Imaging Studies

• Contrast‑enhanced CT scan of the abdomen and pelvis – evaluates tumor size, local invasion, and distant metastasis (liver, peritoneum).
• Positron emission tomography (PET‑CT) – useful for detecting occult metastases and assessing treatment response.
• Magnetic resonance imaging (MRI) – particularly for liver metastases or when CT is contraindicated.

Staging

Staging follows the AJCC TNM system (Tumor, Node, Metastasis). Accurate staging guides treatment selection and prognosis estimation.

Treatment Options

Treatment is personalized based on stage, tumor location, patient’s health, and preferences. Multidisciplinary care—oncology, surgery, gastroenterology, radiology, nutrition, and palliative services—is the standard.

Curative‑Intent Treatments (Stage I‑III)

• Surgery
  • Subtotal (distal) gastrectomy – removal of the lower two‑thirds of the stomach, common for cancers in the antrum.
  • Total gastrectomy – removal of the entire stomach, indicated for proximal or diffuse tumors.
  • Reconstruction (Roux‑en‑Y gastrojejunostomy) restores continuity of the digestive tract.
  • Lymphadenectomy (D2 dissection) is routinely performed to remove regional lymph nodes.
• Peri‑operative chemotherapy – regimens such as FLOT (5‑FU, leucovorin, oxaliplatin, docetaxel) improve survival; commonly given before and after surgery (e.g., MAGIC trial).
• Neoadjuvant (pre‑operative) therapy – for locally advanced tumors (T3‑T4 or node‑positive) to shrink the tumor and increase the chance of complete resection.
• Radiation therapy – combined with chemotherapy (chemoradiation) for select cases, especially when surgical margins are close.

Advanced or Metastatic Disease (Stage IV)

• Systemic chemotherapy – standard first‑line options include a fluoropyrimidine (capecitabine or 5‑FU) plus a platinum agent (cisplatin or oxaliplatin). The addition of trastuzumab for HER2‑positive tumors (≈20% of gastric adenocarcinomas) improves outcomes (ToGA trial).
• Immunotherapy – checkpoint inhibitors (pembrolizumab, nivolumab) are approved for PD‑L1‑positive or microsatellite instability‑high (MSI‑H) tumors after prior chemotherapy.
• Targeted agents – ramucirumab (VEGFR‑2 antagonist) can be used alone or with paclitaxel in second‑line setting.
• Palliative surgery – may relieve obstruction, bleeding, or perforation, but does not cure disease.
• Supportive care – nutritional support, pain management, and psychosocial services are essential.

Lifestyle and Complementary Measures

• Smoking cessation and limiting alcohol intake improve treatment tolerance.
• High‑protein, small‑frequent meals help maintain weight during therapy.
• Physical activity as tolerated (e.g., walking) can reduce fatigue.
• Consultation with a dietitian experienced in oncology is strongly recommended.

Living with Gastric Cancer

Nutrition

• Eat soft, well‑cooked foods; avoid very hot, spicy, or high‑fiber items that may irritate the stomach.
• Incorporate protein‑rich shakes or supplements if oral intake is insufficient.
• Consider enteral feeding (nasogastric, PEG tube) if you cannot meet caloric needs.

Managing Side Effects

• Nausea & vomiting – prophylactic anti‑emetics (ondansetron, aprepitant) before chemotherapy.
• Diarrhea – loperamide as needed; stay hydrated.
• Peripheral neuropathy – dose adjustments of oxaliplatin; use protective gloves for daily tasks.
• Fatigue – schedule rest periods, light exercise, and address anemia if present.

Follow‑up Care

After curative treatment, most guidelines recommend:

• Physical exam, CBC, and tumor markers every 3–6 months for the first 2 years, then annually.
• CT or endoscopic surveillance based on surgeon’s recommendation (typically every 6–12 months).
• Vaccination for pneumococcal and yearly influenza to reduce infection risk.

Emotional & Social Support

• Join support groups (e.g., GLOW – Gastric Cancer Living Online Worldwide).
• Seek counseling or psychotherapy for anxiety/depression; a cancer diagnosis raises mental health needs.
• Engage caregivers early; discuss advance directives and treatment goals.

Prevention

While not all cases are preventable, risk can be markedly reduced by adopting the following measures:

• Eradicate Helicobacter pylori – testing and treatment (triple therapy) for those infected, especially in high‑incidence regions.
• Maintain a healthy diet – plenty of fresh fruits, vegetables, and whole grains; limit smoked, salted, or processed meats.
• Avoid tobacco and limit alcohol – quit smoking; keep alcohol intake below 1 drink/day for women and 2 drinks/day for men.
• Weight management – aim for a BMI within the normal range (18.5–24.9 kg/m²).
• Regular medical check‑ups – especially if you have a family history or known H. pylori infection.
• Screening in high‑risk populations – endoscopic surveillance every 2–3 years for individuals with chronic atrophic gastritis, intestinal metaplasia, or hereditary diffuse gastric cancer (CDH1 mutation).

Complications

If gastric cancer is left untreated or diagnosed at a late stage, several serious complications may arise:

• Obstruction – tumor blocks the gastric outlet leading to vomiting, dehydration, and malnutrition.
• Upper gastrointestinal bleeding – can cause anemia, fainting, or hemorrhagic shock.
• Perforation – rare but life‑threatening; leads to peritonitis and sepsis.
• Metastatic spread – liver, peritoneum, lungs, and distant lymph nodes are common sites; leads to organ dysfunction.
• Cachexia – severe muscle wasting and weight loss that is not fully reversible with nutrition.
• Paraneoplastic syndromes – such as hypercoagulability (deep‑vein thrombosis) or dermatomyositis.

When to Seek Emergency Care

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Sources: Mayo Clinic, National Cancer Institute, World Health Organization, American Cancer Society, Cleveland Clinic, ToGA trial (Lancet Oncology 2010), MAGIC trial (N Engl J Med 2006), CDC H. pylori guidelines.

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