The gastrointestinal system is one long tube from the mouth down. After we ingest food, it is continuously broken down and digested through different chemical and physical processes. The accessory organs of the gastrointestinal system include the tongue, salivary glands, pancreas, liver and gallbladder. Here is a brief outline of the digestive process:

Figure 1: The Gastrointestinal System¹

1. Food enters the mouth, where the teeth and tongue help you chew it into small pieces. Here, saliva partially breaks down some food and helps us swallow it easily.
2. The bolus (compacted ball of chewed food mixed with saliva) passes through the esophagus, a muscular tube about 25 cm in length.
3. The esophagus empties into the stomach. Here, strong acids and enzymes chemically break down the food, while stomach muscles act like a blender to break it down even more. This produces a thick slurry known as chyme.
4. Chyme from the stomach passes into the small intestine where most of the important molecules from the food are absorbed for our body to use. The small intestine is divided into three distinct segments: (1) the duodenum, (2) the jejunum and (3) the ileum.
5. While in the duodenum, the chyme is exposed to bile (a greenish digestive fluid) secreted by the liver, as well as digestive fluids from the pancreas. These fluids help to further digest the chyme.
6. The small intestine empties into the large intestine. Here, a lot of the water is reabsorbed and the material is processed by healthy gut bacteria which are important for digestion.
7. Finally, the waste material is eliminated through the rectum and anus as feces.

If a gastric cancer diagnosis is made early enough, the disease is more likely to be considered curable. This assessment is made based on the stage of the tumor using the TNM system. Surgery for early gastric cancer tries to cure the disease by cutting out the organs affected by cancer cells. There are several different surgical options available to patients and their doctors. Some of the major ones are explained below.

“Gastrectomy” means to “cut out the stomach”. There are different types of gastrectomy procedures which can be selected based on the location and the extent of a patient’s tumor. Please see Figure 1².

1. Wedge: the tumor is located in the middle area of the stomach, only along the greater curvature (the left-most edge). Only a triangle-shaped area right around the tumor is cut out.
2. Central gastrectomy: a band through the middle of the stomach is removed.
3. Proximal: the tumor is located in the upper stomach only; the part of the stomach closest to the esophagus is cut out.
4. Distal: the tumor is located in the lower stomach only; the part of the stomach closest to the duodenum is cut out.
5. Subtotal: the entire stomach except for the very top (which connects with the esophagus and the gastroesophageal junction) is removed
6. Total: the cancer affects the whole stomach so it must all be cut out. Usually, the lower part of the esophagus and the upper part of the duodenum are also cut out².  

Figure 2: Showing the different regions of the stomach which may be cut out during a gastrectomy surgery; the grey area represents the removed part of the stomach³

“Lymphadenectomy” means to “cut out the lymph nodes”. It is also known as a “lymph node dissection”. This is almost always done with a gastrectomy because lymph nodes are a common secondary site for cancer and they provide an easy route for it to spread through the body. In this surgery, lymph nodes are cut out and inspected for the presence of cancer cells.

One of the biggest ongoing debates in gastric cancer treatment amongst experts is what type of lymphadenectomy should be done. See Figure 2¹

1. D0: lymph nodes are not removed
2. D1: this removes the lymph nodes closest to the wall of the stomach only
3. D1+: this removes more lymph nodes than a D1 resection, but does not touch the nodes along other organs such as the pancreas, as is done in a D2 resection.
4. D2: this removes the lymph nodes closest to the wall of the stomach and some lymph nodes located further from the stomach near major blood vessels and other organs.
5. D3: this removes the greatest number of lymph nodes, including those right next to a large blood vessel called the aorta.

It is important to understand that higher numbers correspond to more nodes being removed. For example, a D2 resection removes all the same nodal groups as a D1+ does, plus a few more! Thus, D2 is a more extensive procedure than D1+ is.

Figure 3: This shows the locations of lymph node groups that are commonly removed in D1 (blue), D1+ (yellow) and D2 (red) lymphadenectomies accompanying a total gastrectomy².

Currently in North America, doctors tend to use the D1 or D1+ technique most often. On the other hand, surgeons in East Asian countries usually use the D2 approach as standard of treatment. Dr. Coburn’s research group has done a lot of work reviewing the lymphadenectomy techniques used in different places, as well as the pros and cons of each approach. 

Understandably, it may become difficult to eat and maintain a healthy lifestyle after having part (or all) of a major digestive organ removed. If the GI tract is one long tube from the mouth onwards, how can food pass from one side to the other if the stomach is gone? To avoid this problem, the two ends of the GI tract on either side of the cut-out portion must be reattached. There are different techniques that a surgeon can use to achieve this and ensure the continuity of the GI tract. Three of these techniques are explained here³:

1. Billroth I: also known as a gastroduodenal anastomosis (“anastomosis” means “connection”). If the duodenum is still usable, it is attached to the bottom of the cut portion of the stomach³.
2. Billroth II: also known as a gastrojejunal anastomosis. Sometimes, the duodenum is not usable because it was also cut out to remove the tumor. In this case, the cut edge of the stomach is attached to the jejunum, which is the second part of the small intestine. It is important to know that the duodenum is the only place where iron is absorbed. So patients whose duodenum is removed are at a greater risk of developing anemia (a condition of low iron in the bloodstream)³.  
3. Roux-en-Y gastrojejunostomy: this method might be used if a large portion of the stomach and duodenum has been cut out. It attaches the very top part of the stomach (where it connects with the esophagus) to the jejunum³.

All three of these methods work by sealing together the two cut ends of the GI tract, so that food can pass through uninterrupted from the esophagus to the stomach and the small intestine.

Figure 4: Shows three major reattachment techniques of the stomach to the small intestine after a distal gastrectomy. Far left is Billroth I, middle is Billroth II, far right is Roux-en-Y

1. National Institute of Diabetes and Digestive and Kidney Diseases. Your Digestive System and How it Works. Available from: https://www.niddk.nih.gov/health-information/digestive-diseases/digestive-system-how-it-works . [Accessed: July 2, 2018].
2. Tamura, S. et al. Lymph node dissection in curative gastrectomy for advanced gastric cancer. International Journal of Surgical Oncology. 2011. Available from: doi: http://dx.doi.org/10.1155/2011/748745.
3. Virginia Surgery Associates. Gastric Surgery. Available from: https://www.vasurgery.com/surgical-procedures/general-surgery-2/gastric. [Accessed: June 21, 2018].
4. Zong, L. “Billroth I vs Billroth II vs. Roux-en-Y following distal gastrectomy: a meta-analysis based on 15 studies”. Hepatogastroenterology. 2011. 58:109(1413-1424). Available from: doi: 10.5754/hge10567.

In a clinical trial conducted in Spain, researchers wanted to look at the effects of prehabilitation on surgery outcomes in individuals undergoing abdominal surgery. 125 participants were divided into a control group and an intervention group.

• The control group received the usual standard care given before surgery. The standard care included some nutritional advising and general guidelines on staying well. This may be different for each hospital.
• The intervention group was given a personalized prehab program in addition to standard care for 6 weeks to follow. The prehab program included supervised high-intensity endurance training sessions and physical activities to follow at home.

What was measured in the study? 

• Endurance was measured based on the duration of riding a stationary bicycle.
• Number of complications after surgery

What were the results of the study?

• Participants were able to increase their endurance by 218%.
• Participants experienced fewer health complications after surgery
• There was a lower risk of cardiovascular conditions following surgery 

How may this study help patients and researchers? 

This study showed that prehabilitation including high-intensity endurance exercise is effective in building strength before going into surgery. Anyone may be at risk of developing complications or experiencing a decline in health after a major surgery. There is encouraging evidence that prehab may reduce the challenges that may arise during your recovery from surgery. 

Click here to learn more about the study

In another clinical study conducted in Canada, researchers looked at the effects of exercise and nutrition in patients with esophagogastric cancer after their cancer surgery. 51 patients were divided into a control and a prehab group.

• The control group received standard care including some recommendations on staying healthy before surgery. 
• The prehab group was given an exercise and nutrition program to follow as well as standard care. The exercise program occurred 4 times per week and consisted of cardio and strengthening activities tailored to each individual.
• In the nutrition program, participants consulted with a dietitian for dietary advice and were prescribed whey protein supplements if needed. 

What was measured in the study?

• Physical health was measured based on a walk test where patients were asked to walk back and forth on a 20 metre course for 6 minutes.
• Physical health was measured from the beginning to the end of the prehab program and 4-8 weeks after surgery.

What were the results of the study?

• 62% of the individuals in the prehab program were able to significantly improve their physical health before undergoing surgery.
• Many were able to maintain their strength after surgery.

How may this study help patients and researchers? 

This is the first randomized clinical trial that has demonstrated that prehabilitation can improve strength in patients with esophagogastric cancer and maintain these improvements even after surgery. This is important because cancer treatments such as surgery, chemotherapy, or radiation may lead you feeling worse even if your cancer is responding to treatment.  These findings suggest that physical and nutritional care in prehab can be integrated into cancer treatment plans to better prepare you for your treatment. 

Click here to learn more about the study

A study completed in Spain examined the influence of exercise-based prehab programs for patients with esophageal and gastric cancer undergoing chemotherapy followed by surgery.

• All 40 individuals in the study participated in interval and respiratory muscle training for 5 weeks. The prehab program was scheduled after the completion of chemotherapy until the date of surgery.
• Each participant also had a nutritional consultation with a dietitian. 

What was measured in the study? 

• Physical health was measured based on a cardiopulmonary exercise test. In this test, breathing levels and heart rate were recorded when patients participated in a stationary bicycle exercise and a 25 metre walk.
• Physical health was measured before chemotherapy treatment, after completion of chemotherapy, and before surgery.

What were the results of the study?

• Patients were able to regain or even improve their health after chemotherapy as a result of the exercise program.
• Patients reported improvements in social wellbeing, an increase in appetite, and were feeling less fatigue.

How may this study help patients and researchers? 

Patients with gastric cancer are frequently treated with chemotherapy before undergoing surgery. Chemotherapy can cause harsh side effects that can make you feel more exhausted than normal.  Researchers in this study were able to show that exercise-based prehabilitation can help overcome those negative side effects in patients with esophagus or gastric cancer. Prehab may help you recover and regain your strength after chemotherapy and prepare you for surgery next. 

Click here to learn more about the study

Another study in Denmark examined the impact of exercise training in patients with gastro-oesophageal junction cancer during chemotherapy. Researchers wanted to know if exercise training can be safe for patients to participate during chemotherapy and its effects on physical health and surgical complications. 62 participants were split into a control group and an exercise prehab group.

• The control group received standard care, which consisted of some general recommendations on staying healthy before surgery.
• The exercise group participated in aerobic and resistance exercises supervised by an instructor two times each week. 

What was measured in this study? 

• Physical health was evaluated through an exercise test on a stationary bicycle and measurements of oxygen uptake levels.
• Muscle strength was measured by the maximum weight patients were able to lift with resistance training machines.

What were the results of the study? 

• The exercise group was able to improve their overall physical strength and emotional wellbeing after completing the program.
•  The exercise group was able to tolerate chemotherapy and experienced fewer hospital admissions than the control group.
• After surgery, the number of surgical complications and length of hospital stay were almost the same across the exercise and control group. 

How has this study helped patients and researchers? 

This study showed encouraging results that suggested that exercise may be safe and effective for patients even when they are receiving chemotherapy. Exercise prehab can help strengthen your health and well-being during chemotherapy while also building enough energy for you to complete surgery.

Click here to learn more about the study