Side effects of surgery for stomach cancer

Side effects can happen with any type of treatment for stomach cancer, but everyone’s experience is different. Some people have many side effects. Other people have few or none at all.

Side effects can develop any time during, immediately after or a few days or weeks after surgery. Sometimes late side effects develop months or years after surgery. Most side effects will go away on their own or can be treated, but some may last a long time or become permanent.

Side effects of surgery will depend mainly on:

  • the type of surgery
  • your overall health

Tell your healthcare team if you have these side effects or others you think might be from your surgery. The sooner they are aware of any problems, the sooner they can suggest ways to help you deal with them.


Pain often occurs because surgery damages tissues. Surgery for stomach cancer is a major operation. It may take time for pain to go away after surgery. The intensity of the pain will depend on the procedure, how you heal and how well you tolerate pain. The healthcare team will prescribe drugs to control pain. Tell them if the pain doesn’t go away or pain medicines don’t relieve it.

Find out more about pain.


Some people may develop an infection in the wound after stomach cancer surgery. This is not a common side effect, but it can happen after any type of surgery. Sometimes tubes are placed into the wound to drain excess fluid. Antibiotics may be used to help prevent or treat an infection. Wound infections are a temporary side effect of surgery that may lead to poor wound healing.

Report signs of infection, such as redness, pus, foul-smelling drainage, fever and increased swelling or tenderness at the incision site, to the healthcare team.

Feeling full after eating or drinking

After surgery for stomach cancer, a person may feel full after eating even small amounts of food (early satiety). Surgery for stomach cancer reduces the size of the stomach and can cause scarring of the stomach wall. Surgery may also damage the vagus nerve, which relaxes the stomach wall when food enters the stomach.

This side effect will improve as the remaining part of the stomach stretches or as the body adjusts to the changes in digestion.

Small, frequent meals (every 2 or 3 hours) may be easier to eat than 2 or 3 large meals a day. Avoid drinking fluids with meals, and avoid large portions of food that are high in fibre.

Report any eating problems to the healthcare team.

Lung problems

Lung problems can occur after surgery for stomach cancer. Lung problems can occur for a variety of reasons, such as the location of the incision, the type of surgery done, pre-existing lung problems or smoking. The 2 main types of lung problems that may occur are a lung infection (pneumonia) and a collapsed lung (atelectasis).

Stopping smoking before surgery helps to prevent lung infections and mucus blocking the bronchial tubes that can cause a collapsed lung. Frequent deep breathing, coughing and turning in bed can help reduce the chance of lung problems after surgery. Report shortness of breath, fever, a dry cough or a cough that produces phlegm or mucus to the doctor or healthcare team.


Diarrhea is a common side effect of stomach cancer surgery, especially if the vagus nerve is damaged during surgery. People may also have a strong sense of urgency with the diarrhea.

Dumping syndrome

Dumping syndrome occurs when food moves too quickly from the stomach into the small intestine. It is a common side effect of stomach cancer surgery, especially a total gastrectomy.

Weight loss

Weight loss is a common problem for people who have had stomach cancer surgery. It can occur because the person can no longer eat large meals. Weight loss can also happen because the remaining stomach or small intestine can’t digest food and absorb fats and nutrients as well as they did before surgery.

Other treatment side effects, such as dumping syndrome, diarrhea and loss of appetite, also make it difficult for people to maintain weight after surgery for stomach cancer.

Vitamin B12 deficiency

Some people who have surgery for stomach cancer may develop a vitamin B12 deficiency. This is because the stomach helps to absorb vitamin B12. People who have had most or all of their stomach removed will need to have injections of vitamin B12 to prevent anemia and other problems.


Bleeding, or hemorrhage, can occur if a blood vessel is not sealed off during surgery. Nursing staff frequently check bandages and drains for heavy bleeding right after surgery. If bleeding occurs and is severe enough, the surgeon may have to take the person back to the operating room to find where the bleeding is coming from and to stop it.

A small amount of bloody drainage may be expected after surgery.

Blood clots

A blood clot in the legs is called a deep vein thrombosis (DVT). A DVT can occur right after surgery because the person cannot move around very well, along with other factors. In the most serious cases, a blood clot can break away and travel to the lungs (called a pulmonary embolus, or PE). This causes shortness of breath and affects the ability of the blood to get oxygen from the lungs. Blood clots in the lungs can potentially cause heart failure.

Taking blood thinners (anticoagulants) and applying compression stockings during and after surgery helps to prevent DVT and PE.

Report any shortness of breath or redness, swelling, pain or cramps in the calf of the leg to your doctor or the healthcare team.

Damage to nearby organs

The pancreas and gallbladder may be damaged during surgery for stomach cancer. In rare situations, this may lead to an inflammation of the pancreas (pancreatitis) or gallbladder (cholecystitis).

Anastomotic leak or stricture

An anastomosis is the area where the small intestine has been joined to the remaining stomach or to the esophagus (if the stomach has been removed).

In rare situations, the anastomosis may not heal properly. When this happens, the intestinal fluids leak out into the abdomen (anastomotic leak). Surgery is needed to repair the leak.

An anastomotic stricture occurs when the tissues around the anastomosis become narrowed. This can make it difficult or painful for a person to swallow food. Using an endoscope, the surgeon may treat the stricture by stretching the tissues or by placing a stent into the stricture to keep it open.

Gastroesophageal reflux disease

Gastroesophageal reflux disease (GERD) is a disorder in which the contents of the stomach (including stomach acid) back up into the esophagus (reflux) and cause heartburn and discomfort in the upper abdomen or chest. GERD can be a side effect of stomach surgery.

The healthcare team may prescribe antacid medicine to prevent or reduce GERD.

Hole (perforation) in the wall of the stomach

An endoscopic mucosal resection (EMR) carries a risk of creating a hole in the wall of the stomach. This may happen if too deep a cut is made by the tool attached to the endoscope. If the perforation is severe, surgery may be needed to repair it.

Blind loop syndrome

Blind loop syndrome is when the loop of duodenum that remains after a distal gastrectomy becomes partially or completely blocked. This part of the duodenum is where the bile duct is attached after part of the stomach and the first part of the duodenum are removed in a distal gastrectomy. Partially digested food may slow or stop moving through the intestines. This may lead to infection and malnutrition. Blind loop syndrome can also cause upper abdominal pain, nausea and vomiting, and fatty stools. People may be given antibiotics to fight the infection, and some may need surgery to relieve the blockage.

Expert review and references

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