Your stomach is a bagged shaped organ of the digestive tract. Its inner wall is lined by glandular cells that secrete acids and enzymes during digestion of food. The stomach is located between the esophagus and the first portion of the intestine. It receives foods from the esophagus through an opening called cardia. Once in the stomach, foods are broken apart and thoroughly mixed with gastric acid, and then passed through another passage called pylorus. This very important organ can be affected by many medical conditions, among which is cancer.
Stomach cancer is a malignancy that develops in the tissues of the stomach. Your stomach may be subject to several types of cancers; however, in most cases, the primary cancer of the stomach is an adenocarcinoma, a form of stomach cancer that develops in the cells of the glands of the mucous membrane layer of the stomach. Although rare, a cancerous growth can begin in any part of the stomach.
Stomach Cancer Statistics
Stomach cancer is the second leading cause of cancer death worldwide, particularly in Japan, China, Chile, and Ireland. It is estimated that stomach cancer causes 800,000 deaths worldwide every year. In 2009, about 12,820 men and 8,310 women were diagnosed with stomach cancer in the United States according to the American Cancer Society. However, in the last forty years the incidence of stomach cancer has been declining in Europe, North America, and particularly in the United States.
Stomach cancer incidence varies by age. From 2002-2006, the median age at diagnosis for cancer of the stomach was seventy-one years of age. The percentages and ages of people diagnosed with stomach cancer during that period (2002-2006) include:
- 0.1% under age 20
- 1.5% between age 20 and 34
- 4.8% between age 35 and 44
- 11.6% between age 45 and 54
- 17.7% between age 55 and 64
- 24.6% between age 65 and 74
- 27.7% between age 75 and 84
- 12.0% 85+ years of age
Stomach Cancer Causes
Your stomach is a muscular pear-shaped organ of the digestive tract. It is located between the esophagus and duodenum, which allows it to receive food chewed in the mouth and swallowed into the esophagus. One of the main functions of the stomach is to provide digestion of foods by its mechanical and chemical functions. It is an important organ that constantly works. The stomach can be attacked by cancer.
The causes of stomach cancer are not well known. Cancer occurs in precancerous cells or tissue altered by chemical or mechanical injuries. Stomach cancer tends to grow around an existing injury such as atrophic gastritis (chronic inflammation of the stomach mucosa).
In general, you have stomach cancer when there are errors in the process of DNA replication of certain cells of your stomach. Genes can be mutated due to a confrontation with a virus, parasite, or bacteria. A cell mutation may also be the result of an unhealthy lifestyle (pollution exposure, smoking, alcohol, and certain unhealthy foods) that lead to genetic changes responsible for abnormal multiplication of cells.
Although rare, sometimes cell mutations have their origin in their genetic material. This applies to people who have developed cancer as a result of a genetic mutation passed down from their parents.
Stomach Cancer Risk Factors
In some cases of stomach cancer, the causative factor of the disease is not identified; the cancer just occurs. Sometimes, however, some factors are known. Common risk factors that are often involved in the development of stomach cancer are:
- Diet – Consume a diet high in starch, salt and smoked meats, low in protein, fruits and vegetables.
- Aflatoxin fungus – consummation of food contaminated with aflatoxins
- Surgery – history of surgery to remove gastric or duodenal ulcers
- Environment – Living in a disadvantaged socio-economic group or environment puts you at high risk of becoming a victim of stomach cancer.
- Gastric ulcer – Although it is controversial, some scientists believe that gastric ulcers can lead to the development of gastric cancer.
- Helicobacter pylori – Infection by helicobacter pylori is recognized as favoring gastric cancer. In addition, this bacterium is responsible for a certain percentage of gastric ulcers.
- Tobacco – There is no scientific evidence showing that tobacco and alcohol play a role in the development of stomach cancer; however, since tobacco is highly carcinogenic, some researchers believe it may contribute in the development of the disease.
- Age – Stomach cancer is diagnosed mostly in older people.
- Family history – If you have a family history of stomach cancer, you are at higher risk.
- Sex – Men are more victims of stomach cancer than women are.
- Geography – Cancer of the stomach is more common in Southeast Asia (Japan) and Central Europe.
- Diseases – Some rare diseases are considered as causative factors of stomach cancer: pernicious anemia (also called Biermer’s anemia, Addison’s anemia or Addison–Biermer anemia), Menetrier’s disease (also called hyperplastic hypersecretory gastropathy) and gastric adenomas (pre-malignant condition in the stomach).
- Some professions – Certain professions increase your risk become a victim of stomach cancer:
1) coal mining
2) nickel refining
3) manufacturing products containing lead
4) rubber and timber processing
5) exposure to asbestos
Types of Stomach Cancer
There are different types of stomach cancer:
Stomach Adenocarcinoma -You suffer from adenocarcinoma of the stomach when the cancer develops in glands of the gastric mucosa, a group of cells that secrete mucus to protect the lining of your stomach from acidic and other pathogenic substances. Adenocarcinoma is often due to complications from stomach ulcer. Adenocarcinoma of the stomach represents 85 to 95% of cancers of the stomach.
Stomach Lymphoma – Lymphomas of the stomach are a rare form of cancer accounting for less than 2% of stomach cancers. It is characterized by malignant proliferation of lymphoid cells in the walls of the stomach. This type of cancer tends to grow rapidly, which makes it very life threatening.
Carcinoid cancer – You have carcinoid of stomach (gastric carcinoid) when the cancer develops in hormone-producing cells of your stomach. Gastric carcinoid is another rare malignant tumor that accounts for about 1-2% of all stomach cancers.
Gastrointestinal stromal tumor (GIST) – This form of stomach cancer begins in a group of cells found in your gastrointestinal tract called interstitial cells of Cajal (ICCs) or “pacemakers” of the GI tract. GIST is account for 1-3% of all stomach cancers.
Stomach Cancer Symptoms
As most cancers, stomach cancer is often asymptomatic at the beginning. Even if the symptoms occur, they are often nonspecific and insignificant. You can spend a long period of time with the tumor without noticing its existence. In most cases, when symptoms finally emerge, the cancer has already metastasized to other parts of your body, which often leads to a poor prognosis.
In general, signs and symptoms of stomach cancer include:
- unreasonable weight loss
- difficulty in swallowing
- weakness and fatigue
- nausea and vomiting
- diarrhea or constipation
- burning sensation (heartburn)
- loss of appetite (mostly for meat)
- abdominal pain or discomfort
- stomach bloating (principally after meals)
- vomiting (which may contain blood).
Stomach Cancer Complications
Anatomically, your stomach is in close contact with your liver (at right), spleen (at left), pancreas (behind), diaphragm (at the top), and the intestines (beneath). Therefore, cells of the stomach tend to spread into these organs to form other cancers called metastasis.
Stomach cancer treatment itself can lead to complications. Removal of the stomach always leads to nutritional problems. In addition, cancer can recur after initial treatment. To prevent complications during and after treatment, respect all advice and appointments of your doctor, and adopt a healthy lifestyle. A healthy diet is also important.
Stomach Cancer Diagnosis
If you experience stomach cancer symptoms, your doctor will ask you questions about the characteristic of the symptoms and your medical history. In addition, he will do a physical exam, looking for signs indicating the cancer: palpable mass in your stomach, difficulty in swallowing, etc. However, small sized-tumors rarely cause symptoms. Symptoms start emerging when the tumor has become large or metastatic, which makes the diagnosis of stomach cancer often delayed.
Even if there are typical symptoms of stomach cancer, your doctor may not confirm the disease. In general, to confirm the diagnosis, other more specific tests are needed. These include blood tests, gastroscopy, thoraco-abdominal-pelvic CT, exploratory laparoscopy, and biopsy.
Blood tests – Your physician may collect a sample of your blood for laboratory analysis. Usually, a specialist will analyze the appearance and content of your blood searching for pathogenic signs. The lab specialist can detect tumor markers, such as carcinoembryonic antigen (CEA) and carbohydrate antigen (CA). This step allows your oncologist to evaluate your organ functions and detect abnormalities that may indicate the presence of a stomach cancer.
Gastroscopy – An upper gastrointestinal endoscopy allows your doctor to visualize the interior lining of your upper gastrointestinal including the esophagus, stomach, and duodenum (the first part of your small intestine). In addition, it allows your physician to take samples of stomach tissue to examine under microscope in order to confirm the diagnosis. During the exam, a miniature camera (endoscope) will be inserted through your mouth into your esophagus, stomach, and duodenum. An upper gastrointestinal endoscopy can detect small tumors at early stage and/or other lesions on the gastric mucosa.
Biopsy – It is necessary for your physician to perform a histological examination of cells taken directly from your stomach lining. Biopsies must be multifaceted to accurately confirm the diagnosis. The biopsy can be combined with an ultrasound to correctly identify the stage of the cancer. The ultrasound can also help determine the location and extent of the tumor.
Stomach Cancer Stages
Once the cancer is found in your stomach, the next step is to stage it or find out the extent of the tumor. For this, your physician may perform X-rays, ultrasounds, and CT scans. In general, stomach cancer progresses in the following stages:
- Carcinoma in situ (CIS) – The cancer has not spread beyond the lining of the stomach tissue.
- Stage I – A stage 1 stomach cancer is not aggressive; the chance of recovery is high. The tumor is found in the layer of tissue that lines the inside of the stomach. Although rare, cancer cells can spread to nearby lymph nodes.
- Stage II – Although a stage 2 stomach cancer is still not aggressive, the tumor has spread into the muscular layer of the stomach wall; lymph nodes may also be affected.
- Stage III – At this stage, the cancer has become aggressive and invaded all layers of the stomach wall; the tumor has also spread into lymph nodes.
- Stage IV – A stage 4 stomach cancer is very aggressive. The tumor has affected not only the tissue of the stomach but also nearby structures. In some cases, the cancer cells can travel to the spleen, liver, bone, lung,or/and brain.
- Recurrent – Cancer has returned after initial treatment.
Stomach Cancer Treatment
There is no single treatment for stomach cancer; each person with stomach cancer may be assigned different treatment options depending on the specific characteristics of cancer and state of health. In general, before establishing a treatment plan, your oncologist will consider the size and stage of the tumor. He will also consider your age. Conventional treatments for stomach cancer include surgery, radiotherapy, and chemotherapy.
The type of surgical intervention performed in the treatment of stomach cancer depends on the nature, location, and size of the tumor. Based on your condition, your doctor may perform:
Removal by endoscopy – You will be recommended this surgical technique if you have a small size-tumor. During the surgery, your surgeon inserts a lighted tube with a camera (endoscope) into your stomach in order to reach the tumor and remove it and a margin of healthy tissue surrounding it.
Partial gastrectomy – If your cancer was detected at an early stage (stage 1 for instance), your surgeon may perform a partial gastrectomy to remove a portion of the stomach affected by the cancer. After ablation, the remaining stomach will be then be reconnected to the first section of the small intestine.
Total Gastrectomy – Total gastrectomy involves complete removal of the stomach. After the diseased stomach is removed, your surgeon will establish a continuity between your esophagus and your duodenum. In general, total gastrectomy is indicated for advanced stomach cancer.
Splenectomy – In case you have a type T3-T4 cancer associated with swollen/enlarged lymph nodes (lymphadenopathy), your surgeon may perform a splenectomy, partial, or complete surgical removal of the spleen. Splenectomy is not always practiced in the treatment of stomach cancer; it puts you at increased risk of infections, including pneumococcal and meningococcal infections.
Complications related to the surgery
Stomach cancer surgery can provide good results; however, it is not without consequences. Following surgery for stomach cancer, you may experience intra-abdominal infections and/or pancreatitis. In addition, the gastrectomy may cause:
- anastomotic disunion
- incisional hernia
- dumping syndrome
- deficiency in iron, vitamin B12 and/or folic acid.
Radiation therapy (radiotherapy)
Radiation therapy aims to destroy cancer cells and shrink the tumor in your stomach. Unlike chemotherapy, radiotherapy treats a specific area in your body, specifically, the tumor and small surrounding health tissue. The radiotherapy can be performed alone or in combination with surgery or chemotherapy. However, radiotherapy alone has not proven its efficacy in the treatment of stomach cancer, unless the tumor is well localized. Therefore, it is sometimes used in the palliative treatment or in cases of obstruction of the orifice above or below the stomach by the tumor. Radiation therapy may also be recommended in cases of gastric bleeding.
Although radiation therapy is less toxic than chemotherapy, it often causes adverse effects:
- general malaise
- redness and dryness of the skin
- nausea and vomiting
- decreased appetite
Chemotherapy involves taking, mostly intravenously, powerful chemicals to kill cancer cells. The chemotherapy agents act on the DNA of the cells to block certain stages of their division, preventing their proliferation. In cases of metastatic stomach cancer, used as a palliative treatment, chemotherapy improves survival rate and quality of life. However, the results of chemotherapy in the treatment of stomach cancer are conflicting; the drugs are not always effective in most patients.
Drugs mostly used to treat metastatic stomach cancer are doxorubicin, epirubicin, 5-fluorouracil, methotrexate, cisplatin and docetaxel. The protocol ELF (etoposide, leucovorin, 5-FU) can also be used because of its better tolerability, especially in fragile or elderly patients.
Chemotherapy is a powerful treatment that causes side effects in most patients:
- nausea and vomiting
- loss of hair
- shortness of breath
- mouth sores
Stomach Cancer Survival Rates
Stomach cancer is often diagnosed in its advanced stages, which makes its prognosis alarming. Most patients in an advanced stage will die one year following the treatment. In the United States, the overall five-year survival rate was estimated at 25.7% for the period of 1999-2005.
Five-year relative survival rates by race and sex for 1999-2005 were:
- 22.5% for white men
- 26.7% for white women
- 22.6% for black men
- 28.4% for black women
Stomach Cancer Prevention
To prevent stomach cancer, you have to reduce all risk factors that can lead to its development:
- Stop smoking.
- Adopt a healthy and balanced diet.
- Consume fruits and vegetables regularly and abundantly.
- Avoid alcohol or consume it in moderation.
- Prevent or treat stomach ulcers.
Eradicate systematically helicobacter pylori if it is found in your stomach.