Gastric cancer

Last updated: January 19, 2022

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Gastric cancer is the fifth most common type of cancer worldwide. Incidence is declining in the United States and Europe but continues to be high in Asia. Development of gastric cancer is associated with several risk factors, including consumption of cured or smoked foods rich in nitrates, increased nicotine intake, and Helicobacter pylori infection. Adenocarcinoma is the most common form, accounting for 95% of cases. Initially, gastric cancer is usually asymptomatic or manifests with nonspecific symptoms such as epigastric discomfort or nausea. Late-stage disease is characterized by symptoms of gastric outlet obstruction and/or signs of distant metastatic disease. Upper endoscopy with biopsy is used to confirm the diagnosis. The mainstay of treatment is endoscopic or surgical resection of the tumor. Depending on the stage of the disease, chemoradiation therapy can be used as neoadjuvant, adjuvant, or palliative therapy. The prognosis varies significantly with tumor stage, but 5-year survival rates are generally low (5% for late-stage disease) because diagnosis is often delayed due to lack of symptoms.

  • Incidence
    • An estimated 27,600 new cases were diagnosed in the US in 2020. [1][2]
    • Highest incidence in South Korea, Mongolia, and Japan [3]
  • Sex: > [2]

Epidemiological data refers to the US, unless otherwise specified.

Exogenous risk factors [2]

Endogenous risk factors [2]

Early stages of gastric cancer

  • Often asymptomatic
  • Loss of appetite, nausea

Late stages of gastric cancer

Confirmatory tests

Laboratory tests

Workup of diagnosed gastric cancer


About half of patients with gastric cancer present with advanced disease at the time of diagnosis.

pTNM classification of gastric cancer [11]
Intent AJCC/UICC TNM Tissue invasion Lymph node metastases Distant metastasis
  • Stage 0
  • None
  • None
  • Stage IA
  • T1, N0, M0
  • Stage IB
  • T1, N1, M0
  • T2, N0, M0
  • Muscularis propria
  • None
  • Stage IIA
  • T1, N2, M0
  • T2, N1, M0
  • Muscularis propria
  • T3, N0, M0
  • Subserosal tissue
  • None
  • Stage IIB
  • T1, N3a, M0
  • T2, N2, M0
  • Muscularis propria
  • T3, N1, M0
  • Subserosal tissue
  • T4a, N0, M0
  • None
  • Stage IIIA
  • T2, N3a, M0
  • Muscularis propria
  • T3, N2, M0
  • Subserosal tissue
  • T4a, N1, M0
  • T4a, N2, M0
  • T4b, N0, M0
  • Adjacent organs/structures
  • None
  • Stage IIIB
  • T1, N3b, M0
  • T2, N3b, M0
  • Muscularis propria
  • T3, N3a, M0
  • Subserosal tissue
  • T4a, N3a, M0
  • T4b, N1, M0
  • Adjacent organs/structures
  • T4b, N2, M0
  • Stage IIIC
  • T3, N3b, M0
  • Subserosal tissue
  • T4a, N3b, M0
  • T4b, N3a, M0
  • Adjacent organs/structures
  • T4b, N3b, M0
  • Stage IV
  • Any T, any N, M1
  • Any structure
  • Any number
  • Yes

Gastric adenocarcinoma

General features

  • Accounts for ∼ 95% of cases [14]
  • Most commonly located on the lesser curvature
  • Arises from glandular cells in the stomach

Lauren classification of gastric adenocarcinoma

  • Intestinal type gastric carcinoma
    • Typically localized
    • Polypoid, glandular formation
    • Similar to an ulcerative lesion with clear raised margins
    • Commonly located on the lesser curvature
  • Diffuse type gastric carcinoma
    • No clear border
    • Spreads earlier in the course of disease
    • Infiltrative growth
    • Diffuse spread in the gastric wall
    • Linitis plastica: gastric wall thickening and leather bottle appearance
    • Composed of signet ring cells: round cells filled with mucin, with a flat nucleus in the cell periphery
    • Associated with E-cadherin mutation [15]
  • Intermediate type (the least common type): should be treated as the diffuse type, as the extent of tumor infiltration is difficult to assess

Gastric conditions

Other types of cancer

Gastrointestinal stromal tumor (GIST) [16]

The differential diagnoses listed here are not exhaustive.

Early-stage disease

Late-stage disease

Perioperative chemotherapy or radiotherapy

For the forms of cancer associated with HER2/neu overexpression and the medication used for treatment, think TRUST HER, GaBriel! (TRUSTuzumab; HER2; Gastric cancer; Breast cancer)


Metastatic disease

The Skeleton (bones), Liver, Lung, and Brain are the structures most commonly affected by hematogenous spread of gastric cancer: Zombie SKELETONs don't LIVE LONG (lung) without eating BRAINs.

Paraneoplastic syndromes

Paraneoplastic syndromes may be signs of visceral malignancies, especially GI carcinomas. These syndromes include:

Always rule out malignancy in patients with acanthosis nigricans.

Postgastrectomy complications


Small intestinal bacterial overgrowth (SIBO)

Efferent loop syndrome

  • Definition: kinking or anastomotic narrowing of the efferent loop that causes emesis and/or a feeling of fullness
  • Management

Afferent loop syndrome

  • Definition
    • Biliary and pancreatic obstruction due to stenosis, kinking, or incorrect anastomosis of the afferent loop
    • Chyme enters the afferent loop instead of the efferent loop and causes loss of appetite, a feeling of fullness, and bilious vomiting with subsequent relief of nausea.
  • Management: surgical treatment

Dumping syndrome

  • Definition: rapid gastric emptying as a result of defective gastric reservoir function, impaired pyloric emptying mechanisms, or anomalous postsurgery gastric motor function

Early dumping

Late dumping

Suspect late dumping syndrome in a patient with previous gastric surgery and hypoglycemia.

Remnant gastric cancer [20][21][22]

We list the most important complications. The selection is not exhaustive.

  • Because there are no early signs, gastric cancer is often diagnosed very late. Around 50% of cancers have already reached an advanced stage that does not allow for curative treatment due to tissue invasion and metastases. [11]
  • If diagnosed at a very early stage, the 5-year survival rate is 95%. [23]
  • Late-stage disease with distant metastases and/or peritoneal carcinomatosis has a poor prognosis (5-year survival rate of ∼ 5%). [24]
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