Despite being less common in the United States, stomach cancer is still the 4th most common cancer and 2nd leading cause of death for cancers.3 The most common areas in the world for stomach cancers are east Asia, eastern Europe, and central and south America. Stomach cancer affects men twice as much as women.
Etiology:
The risk factors associated with stomach cancer include3:
Helicobacter Pylori infection
Family History
Smoking
High intake of salted foods
Low intake of fruits and vegetables
Low socioeconomic level
Decreased use of refrigeration1
Signs & Symptoms:
Fatigue4
Feeling bloated after eating
Feeling full after eating small amounts of food
Heartburn that is severe and persistent
Indigestion that is severe and unrelenting
Nausea that is persistent and unexplained
Stomach pain
Vomiting that is persistent
Weight loss
Diagnostic Procedures:
Blood tests: Blood test is given to check for anemia. Stomach cancer can cause anemia to develop.4
Bowel movement sample: This is done to check for blood in stool.
Abdominal ultrasound:
Chest x-ray: This may show cancer has spread.
Barium meal: Helps to visualize how stomach digestion process.
CT scan
Endoscopy: This test uses a scope to see the inside of your digestive tract. A scope is a long, bendable tube with a light on the end of it. A camera may be hooked to the scope to take pictures. Biopsy may be taken for tests. Small tumors may be removed, and bleeding may be treated during an endoscopy.5
Histology:
Adenocarcinoma accounts for 90-95% of all gastric malignancies.1 Lymphoma, usually with unfavorable histology, is the second most common.
Lymph node drainage:
Lymph node drainage follows the arterial supply.1 Major lymph nodal chains at risk include lesser and greater curvature, celiac axis, pancreaticoduodenal, splenic, suprapancreatic, and porta hepatis. Most lymphatics drain ultimately to the celiac nodal area.
Metastatic spread:
The most common site for distant metastatic spread is to the liver. When the cancer involves the distal esophagus, there is also a greater risk for spread to the lungs.1 Peritoneal contamination is possible if a lesion extends beyond the gastric wall to a free peritoneal surface, and the cancer may also extend directly into the omenta, pancreas, diaphragm, transverse colon, and duodenum.
Grading:
Grade refers to the appearance of the tumor under the microscope.2 Grade 1 (low-grade) - The cancer cells tend to grow slowly, look quite similar to normal cells (are ‘well differentiated’) and are less likely to spread than higher grades. Grade 2 (moderate-grade) - The cells look more abnormal and are slightly faster growing. Grade 3 (high-grade) - The cancer cells tend to grow more quickly, look very abnormal (are ‘poorly differentiated’) and are more likely to spread than low-grade cancer cells.
Staging:
The stage describes how far the cancer has spread.7 The clinical stage is based on the results of physical exams, endoscopy, biopsies, and any imaging tests. The pathologic stage can be determined using the results from surgery in addition to the same test results from the clinical stage. The clinical stage may be used to plan treatment, but sometimes the cancer spreads further than what the clinical stage estimates. The pathologic stage can more accurately predict the patient’s outlook because it’s based on what was found from surgery. The staging described here is the pathologic stage.
The American Joint Commission on Cancer (AJCC) TNM system is the common staging system for stomach cancer. The TNM system for staging contains 3 key pieces of information: • T describes the extent of the primary tumor (how far it has grown into the wall of the stomach and into nearby organs). • N describes the spread to nearby (regional) lymph nodes. • M indicates whether the cancer has metastasized (spread) to distant parts of the body.
Numbers or letters appear after T, N, and M to provide more details about each of these factors: • The numbers 0 through 4 indicate increasing severity. • The letter X means “cannot be assessed” because the information is not available. • The letters “is” refer to carcinoma in situ, which means the tumor is only in the top layer of mucosa cells and has not yet invaded deeper layers of tissue.
American Joint Committee on Cancer (AJCC) TNM Staging Classification for Carcinoma of the Stomach:8 Primary Tumor (T): TX: Primary tumor cannot be assessed T0: No evidence of primary tumor Tis: Carcinoma in situ - intraepithelial tumor without invasion of the lamina propria T1: Tumor invades lamina propria, muscularis mucosae or submucosa T1a: Tumor invades lamina propria or muscularis mucosae T1b: Tumor invades submucosa T2: Tumor invades muscularis propria T3: Tumor penetrates subserosal connective tissue without invasion of visceral peritoneum or adjacent structures T4: Tumor invades serosa (visceral peritoneum) or adjacent structures T4a: Tumor invades serosa (visceral peritoneum) T4b: Tumor invades adjacent structures
Regional Lymph Nodes (N): NX: Regional lymph node(s) cannot be assessed N0: No regional lymph node metastasis N1: Metastasis in 1-2 regional lymph nodes N2: Metastasis in 3-6 regional lymph nodes
N3: Metastasis in seven or more regional lymph nodes N3a: Metastasis in 7-15 regional lymph nodes N3b: Metastasis in 16 or more regional lymph nodes
Distant Metastasis (M): M0: No distant metastasis M1: Distant metastasis
Reprinted from American Cancer Society, 2013.8
Radiation side effects:
Skin irritation at the treatment site, nausea, vomiting, diarrhea, and fatigue.7
Prognosis:
The prognosis of stomach treatment is mostly dependent on the extent of the tumor as well as the location and amount of lymph nodes involved.6 The five year survival rate based on the tumor stage is listed below.
Stage IA 71%
Stage IIA 45%
Stage IIIA 20%
Stage IV 4%
Stage IB 57%
Stage IIB 33%
Stage IIIB 14%
Stage IIIC 9%
Treatments:
Surgery is the primary treatment for operable stomach cancer with a 5 centimeter (cm) margin.6 Inoperable tumors are treated concurrently with radiation therapy and 5-FU chemotherapy. The anterior-posterior (AP), posterior-anterior (PA) treatment is taken to a dose of 45-52 gray (Gy). While it is important that the kidney dose is watched carefully, a proximal tumor in the stomach requires a 3-5 cm margin on the distal esophagus.
TD 5/5:
Organ TD5/5:6 Kidneys 1.8Gy-2.3Gy Liver 3.Gy-3.5Gy Small bowel 4.Gy-4.5Gy Spinal cord 4.5Gy-4.7Gy Heart 4.5Gy Esophagus 5.5Gy
References:
Chao K, Perez C, Brady L. Radiation Oncology Management Decisions. 3rd ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2011.
Lymphoma, usually with unfavorable histology, is the second most common.
Grade 1 (low-grade) - The cancer cells tend to grow slowly, look quite similar to normal cells (are ‘well differentiated’) and are less likely to spread than higher grades.
Grade 2 (moderate-grade) - The cells look more abnormal and are slightly faster growing.
Grade 3 (high-grade) - The cancer cells tend to grow more quickly, look very abnormal (are ‘poorly differentiated’) and are more likely to spread than low-grade cancer cells.
The American Joint Commission on Cancer (AJCC) TNM system is the common staging system for stomach cancer. The TNM system for staging contains 3 key pieces of information:
• T describes the extent of the primary tumor (how far it has grown into the wall of the stomach and into nearby organs).
• N describes the spread to nearby (regional) lymph nodes.
• M indicates whether the cancer has metastasized (spread) to distant parts of the body.
Numbers or letters appear after T, N, and M to provide more details about each of these factors:
• The numbers 0 through 4 indicate increasing severity.
• The letter X means “cannot be assessed” because the information is not available.
• The letters “is” refer to carcinoma in situ, which means the tumor is only in the top layer of mucosa cells and has not yet invaded deeper layers of tissue.
American Joint Committee on Cancer (AJCC) TNM Staging Classification for Carcinoma of the Stomach:8
Primary Tumor (T):
TX: Primary tumor cannot be assessed
T0: No evidence of primary tumor
Tis: Carcinoma in situ - intraepithelial tumor without invasion of the lamina propria
T1: Tumor invades lamina propria, muscularis mucosae or submucosa
T1a: Tumor invades lamina propria or muscularis mucosae
T1b: Tumor invades submucosa
T2: Tumor invades muscularis propria
T3: Tumor penetrates subserosal connective tissue without invasion of visceral peritoneum or adjacent structures
T4: Tumor invades serosa (visceral peritoneum) or adjacent structures
T4a: Tumor invades serosa (visceral peritoneum)
T4b: Tumor invades adjacent structures
Regional Lymph Nodes (N):
NX: Regional lymph node(s) cannot be assessed
N0: No regional lymph node metastasis
N1: Metastasis in 1-2 regional lymph nodes
N2: Metastasis in 3-6 regional lymph nodes
N3: Metastasis in seven or more regional lymph nodes
N3a: Metastasis in 7-15 regional lymph nodes
N3b: Metastasis in 16 or more regional lymph nodes
Distant Metastasis (M):
M0: No distant metastasis
M1: Distant metastasis
Reprinted from American Cancer Society, 2013.8
Stage IA 71%
Stage IIA 45%
Stage IIIA 20%
Stage IV 4%
Stage IB 57%
Stage IIB 33%
Stage IIIB 14%
Stage IIIC 9%
Kidneys 1.8Gy-2.3Gy
Liver 3.Gy-3.5Gy
Small bowel 4.Gy-4.5Gy
Spinal cord 4.5Gy-4.7Gy
Heart 4.5Gy
Esophagus 5.5Gy
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