Managing side effects of stomach cancer and its treatment

Stomach cancer and its treatment can cause side effects. Some of these may be permanent and could change what you can eat, and how your body digests food and absorbs essential nutrients.

Dumping syndrome

As surgery has changed the structure of your stomach, partially digested food can move into the small bowel too quickly. This is called dumping syndrome.

This can especially be a problem with sugary fluids, such as soft drinks, juices and cordial. You may have cramps, nausea, a racing heart, sweating, bloating, diarrhoea or dizziness.

This combination of symptoms most commonly occurs 15-30 minutes after a meal. If they happen 1-2 hours after a meal, they are called late symptoms and can include weakness, light-headedness and sweating. Symptoms are often worse after eating foods high in sugar.

To help manage dumping syndrome, try eating smaller meals, chew your food well, choose high-protein foods (e.g. lean meats, fish, eggs, dairy, beans) and starchy foods (e.g. pasta, rice, potatoes), avoid food and drinks high in sugar, and try not to drink with meals.

Anaemia and osteoporosis

After surgery to remove part or all of your stomach, your body may not absorb certain vitamins and minerals as well as before. When these levels are low, you may develop additional symptoms.

Calcium

Over time, low calcium can cause your bones to become weak and brittle and break more easily (osteoporosis). Your doctor will talk to you about exercise, your diet and drug treatments.

Vitamin B12

The most common symptom of low B12 is tiredness. Other symptoms include pale skin, breathlessness, headaches, a racing heart and appetite loss. Your doctor may recommend regular B12 injections. If you had a total gastrectomy, you will need regular injections as your body will no longer be able to absorb B12.

Iron

Low iron can lead to iron deficiency anaemia, which can cause fatigue, dizziness and shortness of breath. You may need an iron infusion, when iron is given as a liquid through a drip inserted into a vein.

You will probably have regular blood tests to check your vitamin and mineral levels. 

Eating during and after treatment

You need to eat and drink enough to get the nutrition your body needs and to avoid dehydration. It is also important to maintain your weight to prevent malnutrition. You may need a feeding tube during or after treatment if you are unable to eat and drink enough to meet your nutritional needs.

After treatment, you may find that some foods are uncomfortable to eat and cause digestive problems. You will need to try different foods and change your eating habits, such as eating smaller meals more often throughout the day.

Ask your doctor for a referral to a dietitian with experience in cancer care – they can give you more information. If you are eating less than usual, it is often recommended that you have high-energy and high-protein foods and follow healthy eating guidelines.

Learn more about nutrition for people living with cancer.

How to prevent unplanned weight loss

• Have a snack or small meal every 2–3 hours if you have lost your appetite and don’t feel hungry enough for a big meal.
• Keep a variety of snacks on hand (e.g. in your bag or car).
• Eat when you feel hungry or crave certain foods. 
• Try eating different foods to see if your taste and tolerance for some foods have changed.
• Eat slowly and stop and rest when you are full.
• Try to drink fluids that add energy (kilojoules), such as milk, milkshakes, smoothies or nutritional supplement drinks recommended by your dietitian.
• Prevent dehydration by drinking fluids between meals (30–60 minutes before or after meals).
• Ask your dietitian how you can increase your energy and protein intake.
• Use a food diary to keep a record of how you react to certain foods.