Gastric cancer: Nursing

Gastric cancer is a malignant tumor that originates in the stomach, and is one of the most common types of cancer. First, let’s recall the physiology of the stomach. The stomach is a hollow, J-shaped organ of the digestive system that stores food, mixes it with gastric juices and empties it into the small intestine. It is divided into four parts, called the cardia, the fundus, the body and the pylorus. Now, let’s zoom into the wall of the stomach, which is made up of four layers. The outermost layer is called serosa or adventitia, and it faces the abdominal or peritoneal cavity.

This is the space between the abdominal wall and abdominal organs that is lined with peritoneal membrane and contains a small amount of serous fluid. Next layer is muscularis, which contracts to stir the food and move it further into the guts. After that is the submucosa, which consists of a dense layer of tissue that contains blood vessels, lymphatics, and nerves. And finally, there’s the innermost layer, called the mucosa, which consists of a simple columnar epithelium that forms many invaginations, called gastric pits, which connect to gastric glands. The gastric glands are composed of cells that produce gastric acid, which helps break down food and inactivate ingested bacteria; mucus, which protects the mucosa from the gastric acid; enzymes, which break down proteins; and intrinsic factor, which is a protein necessary for vitamin B12 absorption.

Now, the exact cause of gastric cancer is unknown, but there is usually a genetic mutation in a cell of the gastric mucosa. These include mutations in a tumor suppressor gene, which results in loss of inhibition of cell division, or a proto-oncogene, which stimulates cell division. And these mutations can be hereditary, meaning that the client inherits the mutation from one of their parents, or non-hereditary, also known as sporadic, which occur de novo or spontaneously. Whatever the cause is, the chance of developing gastric cancer increases with certain risk factors. Modifiable risk factors include Helicobacter pylori infection, gastric ulcers, gastroesophageal reflux disease and achlorhydria, which refers to low or absent HCl production by the stomach leading to a more alkaline environment that is suitable for bacterial growth.

Chronic inflammation and atrophic gastritis can lead to intestinal metaplasia, where the epithelial cells type is changed, which is considered a precancerous condition. Other risk factors include diet high in salted, smoked and processed foods, low vegetables and fruits intake, obesity, contaminated drinking water, exposure to irritants such as smoking and alcohol, and prolonged use of NSAIDs, since they block production of prostaglandins which normally stimulate gastric mucus secretion. On the other hand, non-modifiable risk factors include age above 40, being assigned male at birth, family history of gastric cancer, previous gastric surgery, radiation exposure, gastric polyps, Epstein-Barr virus infection and lymphoma, such as mucosa associated lymphoid tissue, or MALT lymphoma.

Okay, now let’s look at the pathology of gastric cancer. The most common type of gastric cancer is adenocarcinoma, which occurs when an epithelial cell becomes mutated and cancerous, and starts dividing uncontrollably, forming a tumor mass. As the tumor keeps growing, new blood vessels also develop via angiogenesis to supply it. Eventually, cancerous cells start invading neighboring tissues, such as the pancreas and transverse colon, and may even spread to nearby or even distal lymph nodes, such as left supraclavicular, or Virchow’s nodes, left axillary, or Irish nodes, and periumbilical, or Sister Mary Joseph nodes. Gastric cancer can also metastasize to distant organs, such as the liver via portal circulation, and the lungs and bones via systemic circulation. Finally, it can form seedlings that metastasize to the peritoneum, and even involve both the ovaries, causing a particular type of tumor, called Krukenberg’s tumor.

So, the clinical manifestations of gastric cancer vary based on the size and location of the tumor. Initially, clients can be completely asymptomatic. Over time, the body mounts an immune response to fight the tumor off, so clients can experience unintentional weight loss, fever, and malaise. At an early stage, clients might also experience dyspepsia, or indigestion, abdominal discomfort and early satiety. If the tumor grows enough to physically obstruct the stomach, it can cause narrowing of the lumen; dysphagia; nausea; vomiting; hematemesis, or vomiting of blood; or melena where the discolored blood can also appear in the stool, making it black. Blood loss and impaired gastric function can also cause iron deficiency anemia. In some cases, a palpable epigastric mass may also be present. Clients can also experience epigastric pain, retrosternal pain, or back pain due to the compression of nearby nerves. Finally, with peritoneal metastases, clients can develop ascites, which is a collection of free fluid in the abdominal cavity.

Diagnosis of gastric cancer starts with the client’s history and physical assessment, followed by esophagogastroduodenoscopy with biopsy. Laboratory test results are generally non-specific and may show low hematocrit and hemoglobin levels, as well as elevated blood levels of tumor markers like CEA, and CA 19-9. Hypoalbuminemia, increased bilirubin and liver enzymes can also be found if there’s liver metastasis, while increased amylase and lipase levels suggest pancreatic involvement. Once diagnosis has been confirmed, imaging tests like abdominal or pelvic CT scan, MRI, and positron emission tomography, or PET can be used to stage the tumor with the TNM classification, by defining the Tumor location and looking for lymph Node involvement or Metastasis.

Treatment for gastric cancer depends on its aggressiveness and extension. Small, localized tumors can be treated with partial gastrectomy, which is when the affected part of the stomach is surgically removed. The remaining healthy part of the stomach can be sutured to the duodenum, which is also known as the Billroth I procedure or gastroduodenostomy, or it can be sutured to the jejunum, which is known as the Billroth II procedure or gastrojejunostomy. On the other hand, for clients with larger tumors, the treatment of choice is total gastrectomy where the whole stomach is removed, while the esophagus is sutured to the jejunum, which is also known as esophagojejunostomy. Also, any involved nearby lymph nodes should be resected. Metastasectomy or removal of metastatic cancerous tissues in other organs can also be performed. In addition, many clients may require a gastrostomy, where the stomach contents are diverted into an artificial opening in the abdominal wall called a stoma, and ultimately eliminated into a pouch or bag.