ALL STEM CELLS

4 significant malignancies of the stomach:
1) Adenocarcinoma (most common-95%)
2) Carcinoids (just discussed)
3) Lymphoma
4) GIST (gastrointestinal stromal tumors; e.g., leiomyosarcoma)
There are 2 distinct forms of gastric adenocarcinoma: a proximal diffuse type and a distal intestinal type. The
incidence of distal gastric cancer had been decreasing until about 20 years ago; since then, its incidence
has been holding steady. The proximal type has been steadily increasing.

The risk factors and associations with gastric cancer include:
• Chronic H. pylori infection
• Metaplastic (chronic) atrophic gastritis
• Menetrier disease(= large stomach folds from epithelial cell hyperplasia)
• Adenomatous gastric polyps (rare)

It appears that distal gastric cancer is most strongly associated and observed with environmental factors, especially:
• A diet low in fruits and vegetables and high in dried, smoked, and salted foods
• Foods rich in nitrates and nitrites (animal studies)
Acanthosis nigricans is a reactive skin condition with velvety dark plaques in the intertriginous areas (areas where opposing skin surfaces touch and rub). It is usually due to Type 2 diabetes and obesity, but it is also associated with various GT and lung malignancies. Of these malignancies, acanthosis nigricans is most often associated with gastric cancer.
Note that with H. pylori infection, some patients may develop MALT (extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue). This is diagnosed by EGD with biopsy. When the H. pylori infection is treated, the MALT may resolve. Endoscopic follow-up is necessary.
Neither alcohol consumption nor gastric ulcers has been proven to cause gastric cancer-as previously thought-even though gastric cancer can present as an ulcer.

Diagnosis of gastric cancer:
Often an ulcer is picked up on EGD or barium contrast study (double contrast is better). If it appears benign, it can be treated. Biopsy of gastric ulcers is recommended, especially nonhealing ulcers, if clear etiology is not found (H. pylori/NSAID).
For a nonhealing ulcer, endoscopy with multiple biopsies is the diagnostic procedure of choice. Tumor markers, such as carcinoembryonic antigen (CEA) and alpha fetoprotein (AFP), are not useful as early markers for gastric cancer.
Prognosis is determined by stage (TNM classification), using CT scan and endoscopic ultrasound. Because it is
largely asymptomatic until advanced, < 10% are found in the early gastric cancer stage (EGC, confined to the mucosa and submucosa, TIN0M0). The 5-year survival rate is 85-90% for treated EGC(Early Gastric Cancer) and only 3% for treated invasive, metastatic gastric cancer. Treatment consists of surgical removal of the cancer and adjacent lymph nodes. Adjuvant combination chemoradiation prolongs survival.
POSTGASTRECTOMY SYNDROMES
• Dumping Syndrome
• Blind Loop Syndrome<