B48 Gastric tumors

Question 1

What are the types of benign and malignant gastric tumors?

Answer 1

Benign

• Polyps: can be
  
  • Hyperplastic/inflammatory: 75%. These are common, especially in elderly. Reactive hyperplasia of the stroma and inflammation. Edematous epithelium with dilated glands. Small, less than 1cm wide. Occur on the background of chronic gastritis, and may become dysplastic and produce adenocarcinoma.
  • Fundic gland polyps: Occur spordically in some people, always occur in people with familial adenomatous polyposis, but are totally benign. form due to elevated gastrin levels causing hyperplasia (often in people on proton pump inhibitor drugs)
  • Adenomatous polyps: are precancerous lesions in which the polyps show dysplasia. The frequency of dysplasia in hyperplastic polyps increases with their size. Above 2cm in diameter have a very high risk of becoming adenocarcinoma.

Malignant:

• Adenocarcinoma 95% of gastric cancer
  
  • Intestinal type: Associated with H. pylori, chronic gastritis, nitrosamines in smoked food, and alcohol. Preceeded by Intestinal metaplasia and ulceration.
  • Diffuse type: Signet ring neoplastic cells invade the mucosa and form the linitis plastica, leather bottle stomach, due to the desmoplastic reaction of the stroma; connective tissue hyperplasia. Not related to H. pylori, gastritis, or smoke. Involves mutation of E-cadherin.
• MALT lymphoma: 4%​
• Diffuse large B cell lymphoma
• Carcinoid tumors 3%: Tumors from neuroendocrine cells. Can form in response to gastrinoma elsewhere or to proton pump inhibitor therapy. They are slow growing luminal or mucosal tumors. Gastric carcinoid tumors rarely metastasize and are cured by resection.
• Stromal tumors 2% - GIST Gastro-intestinal stromal tumors. Arise from mesenchymal cells in the GI tract. Stomach is the most common site for GISTs to arise. 75-80% of GISTs have an activating, gain of function mutation in c-KIT receptor tyrosine kinase. 8% of GISTs without c-KIT mutation have an activating mutation in PDGF Receptor A, also a tyrK. These tumors arise from interstitial cells of Cajal from the ENS, or from a common precursor. Is treated with Imatinib (just like CML). These are not defined as benign or malignant, they are instead high risk or low risk, in which large tumors with high mitotic figures are high risk, and small tumors with low mitotic numbers are low risk. Stomach GISTS are usually less aggressive than intestinal GISTs.

Question 2

What are the differences in epidemiology for inestinal vs diffuse type of gastric adenocarcinoma?

Answer 2

Intestinal types are associated with chronic gastritis and precursor intestinal metaplasia

Occur after age fo 50. Male predominance, 2:!

Diffuse type do not have a known precursor lesion or risk factor.

Occur earliers earlier with no gender bias.

Question 3

How does gastric cancer usually present?

Answer 3

Weight loss,

Abdominal pain due to ulcers,

Anemia due to ulcers and chronic bleeding

Early satiety - especially with diffuse form.

Some rare signs that can be seen with gastric carcinoma:

• Acanthosis nigricans - stomach cancer is the most common cancer associated with this, but can occur with others, esp prostate, breast, and ovary.
• Leser Trelat sign. Acute, rapid development of dozens of hyperpigmented skin lesions “seborrheic keratosis”

Question 4

What is the prognosis of gastric cancer based on?

Answer 4

The depth of invasion into the stomach layers, and the extent of lymph node invasion or metastasis.

5yrS is high, 90%, for early gastric cancer, even if there is some lymph node involvment.

Advanced gastric cancer 5yrS is less than 20%, and unfortunately it is usually discovered at this type of advanced stage.

Overall 5yrS is 30%

Question 5

What causes gastric cancers?

Answer 5

Chronic gastritis - autoimmune, bacterial, chemical-alchol and nitrosamines in smoked foods

Chronic H. pylori infection

EBV infection.

Familial adenomatous polyposis

Blood type A is an important risk factor

Question 6

Where to stomach cancers metastasize to?

Answer 6

via regional lymph nodes, or via peritoneal spread.

to Regional lymph nodes, particularly via Virchow’s node. The Left supraclavicular node, which drains the stomach.

Periumbilical region (sister mary joseph nodule, seen with the intestinal type)

Ovaries (bilateral ovarian tumor-krukenberg tumor, seen with diffuse type. )

Liver metastases

Question 7

What types of cancer metastasize to the stomach?

Answer 7

Metastasese to the stomach are rare.

But when they occur, they are from melanoma or esophageal cancer.

also from the breast, lung, testis, and cervix less often.