Gastric cancer types
Although lymphoma (such as diffuse large cell lymphoma or MALT lymphoma) , gastrointestinal stromal tumour (GIST) and other less common types can arise from the stomach, primary stomach cancer usually refers to carcinoma arising from the lining of the stomach and are of 2 main histopathological types (Lauren’s Classification) :
- Intestinal type (well differentiated)
- Diffuse type (undifferentiated)
The two types are distinguished by light microscopy appearance of biopsy specimens obtained from endoscopy (OGD). Their origins, epidemiology, and genetic profiles are also thought to be different. Compared to diffuse subtype, the intestinal subtype tends to affect males more than females, older more than younger patients and tends to have a better prognosis.
Central to these differences is the cellular adhesion molecules which keep cells tightly together. This is preserved in intestinal type but disrupted in diffuse type stomach cancer. When preserved, the intestinal type gastric cancer tends to form glands and tubules (adenocarcinoma) like other parts of the gastrointestinal tract. However, in diffuse type stomach cancer, the cancer cells do not adhere to one another. The individual cancer cells tend to grow and invade surrounding structures, tissues or organs without forming tubules or glands. The molecular basis of this is loss of E-cadherin, a cell protein involved in adhesion, in diffuse type gastric cancer. It has even been found that there are some families with Hereditary Diffuse Gastric Cancer syndrome whereby the gene CDH1, which codes for E-cadherin is mutated.
Beyond Lauren’s histopathological subtypes mentioned above, the classification of gastric cancers has evolved to include various subtypes based on:
- Location (Gastroesophageal junction vs Gastric)
- HER2 expression (Positive versus Negative)
- Microsatellite stability (Stable versus Unstable)
- Molecular profile (Epstein Barr Virus positive subtype, Microsatellite unstable subtype, Genome Stable subtype and Chromosomal instability subtype)
These classifications have important therapeutic implications. For example, HER2 overexpressing gastric cancers can be treated with the anti-HER2 targeted drug trastuzumab. Gastric cancers which are microsatellite unstable can potentially respond to immunotherapy drugs which target PD-1.
Nutritional aspects of stomach cancer
The process by which food is taken in and used by the body for growth, metabolism, and to replace tissue is called nutrition. Eating the right kinds of foods before, during, and after cancer treatment can help the patient feel healthy, strong and stay fit. A healthy diet includes eating and drinking enough of the foods and liquids that have the important nutrients (protein, carbohydrates, fat, vitamins, minerals, and water) that the body needs.
Malnutrition occurs when the body is not able to get or absorb the nutrients from food. This is malnourishment or malnutrition. In stomach cancer, this can happen from the various ways mentioned before. It also depends on the location of the tumour, whether it is proximal, near the oesophagus, in the body of the stomach or distal before the stomach joins the duodenum or small bowel.
In stomach cancer, there can be specific issues related to nutrition and weight in patients with or without an operation on the stomach, called a gastrectomy.
Gastrectomy – Operation for stomach cancer
Good nutrition is important for cancer patients. For stomach cancer, nutrition prior to surgery is important as this will affect wound healing and avoid complications. Surgeons are aware of this and will try to prepare the patients in the short time before surgery for the needed operation. This may involve nutrition support either via a feeding tube (nasogastric tube) or intravenously (parenteral nutrition) as required.
Gastrointestinal function is disrupted and deranged when patients have a gastric operation. It depends on the extent (proximal, distal) of operation, the volume of gastric tissue removed (partial or total gastrectomy) and the types of stomach reconstruction operation done.
Some patients may have symptoms in the early post operation or post gastrectomy period which eventually settles down to a stable pattern. Chronic problems related to pain, obstruction, stomach motility problems need to be evaluated. Some of the symptoms may include gastrointestinal discomfort, including nausea, vomiting, cramps, and diarrhea, as well as vasomotor symptoms such as sweating, palpitations, and flushing (Post gastrectomy dumping syndrome).
It is not uncommon for patient to lose weight after gastrectomy. There could also be possible nutritional deficiencies that can develop following partial gastrectomy, including malabsorption of vitamins or minerals. At OncoCare Cancer Centre, Singapore, we have a nutritionist, Ms Jackie Green who can advise on diet in such situations.
Advanced stomach cancer and nutrition
Gastric cancer treatment in the advanced cancer patient is challenging. Needing to maintain patient weight and fitness with appropriate nutrition, especially when chemotherapy or other cancer treatment is planned is important. There are potentially several causes of poor nutrition in advanced stomach cancer patients. These can range from anorexia, cachexia from the cancer; poor gut motility, obstruction of gastrointestinal tract, medications related or ascites.
If obstruction from tumour is a problem, bypass with a feeding tube or stent can be an option. A stent would need to be placed endoscopically. Intravenous nutrition is sometimes considered for patients but this has to be discussed in detail with the patient and family because it entails high maintenance and support.
For advanced cancer patients, anorexia or cachexia can cause malnutrition. A careful consultation and discussion is needed to ascertain the cause and identify reversible elements for nutrition. Some of the possible causes in advanced cancer patients (not exhaustive list) could be:
- Obstruction of gastrointestinal tract
- Ileus or poor motility of gut
- Ascites ( fluid in the tummy / peritoneal space)
- Medication or treatment drugs related
- Concurrent other infection
Gastric cancer treatment at OncoCare Cancer Centre
Eating and food is central to many cultures and gastric cancer presents its unique challenges in care of patients. Some of the chemotherapy and anti-cancer drugs used in treatment of gastric cancer (the list is not exhaustive and changes with time) are:
- 5-FU (5-fluorouracil)
- Cisplatin Oxaliplatin
- Paclitaxel and Docetaxel
- Oral Capecitabine (Xeloda)
- Oral TS-1
- Ramucirumab (Cyramza)Tratsuzumab (Herceptin)
Managing stomach cancer at OncoCare Cancer Centre, Singapore, involves treating the cancer and providing the necessary supportive care.
“Expert knowledge means better care for cancer”
|Dr Benjamin Chuah||Dr Wong Nan Soon||MBBCH||MBBS (Singapore)||BAO (Ireland)||M.Med (Singapore)||MRCP (United Kingdom)||FRCP (Edinburgh) MRCP (UK)||FRCP (Medical Oncology)||FAMS (Medical Oncology)|