Food Safety During and After Cancer Treatment

Approved by the Cancer.Net Editorial Board, 10/2016

Food safety is important for people both during and after cancer treatment. Cancer and cancer treatments, such as chemotherapy, radiation therapy, and stem cell/bone marrow transplantation, often weaken the immune system. This makes it harder for your body to protect itself from foodborne illness, also called food poisoning. Foodborne illness is caused by eating food that contains harmful bacteria, parasites, or viruses.

Ask a member of your health care team if you should take special food safety steps. This discussion may include how to safely handle, prepare, and store food. You should also discuss which foods you should avoid and how long you should take food precautions, if needed.

Foods to avoid

Some foods have a higher risk of becoming tainted with bacteria. These include:

  • Unwashed fresh fruit and vegetables, especially leafy vegetables that can hide dirt and other contaminants
  • Raw sprouts, such as alfalfa sprouts
  • Raw or undercooked beef, especially ground beef, or other raw or undercooked meat and poultry
  • Cold hot dogs or deli lunch meat (cold cuts), including dry-cured, uncooked salami. Always cook or reheat these foods until they are steaming hot.
  • Refrigerated pâté
  • Raw or undercooked shellfish, such as oysters.
  • Smoked fish
  • Some types of fish, both raw and cooked, as they may contain high levels of mercury
  • Sushi and sashimi, which often contain raw fish. Commercially frozen fish, especially those labeled “sushi-grade” or “sashimi-grade,” is safer than other fish, but check with your doctor before eating it.
  • Unpasteurized beverages, such as unpasteurized fruit juices, raw milk, raw yogurt, or cider
  • Soft cheeses made from unpasteurized milk, such as blue-veined (a type of blue cheese), Brie, Camembert, feta, goat cheese, and queso fresco or blanco
  • Undercooked eggs, such as soft boiled, over easy, and poached; raw, unpasteurized eggs; or foods made with raw egg, such as homemade raw cookie dough and homemade mayonnaise
  • Deli-prepared salads with egg, ham, chicken, or seafood

Simple steps for food safety

Shop smart.

  • Do not buy food stored or displayed in an unclean area.
  • Do not buy bruised or damaged fruits or vegetables.
  • Do not buy cans that have cracks, dents, or bulges.
  • Pick up foods that can spoil at the end of your shopping trip and store them in a cooler on the way home.

Prepare and clean up foods carefully.

  • Rinse all fresh fruits and vegetables under running water, and dry them with a clean towel or paper towel.
  • Clean the top of cans before opening them.
  • After preparing food, wash your hands for 20 seconds with hot water and soap. Pay special attention to areas between fingers and under nails.
  • Clean your utensils and dishes with hot water and soap.
  • Disinfect your kitchen and cutting boards using 1 teaspoon of liquid, unscented bleach mixed into 1 quart of water.  

Prevent cross-contamination.

  • Keep raw meat, poultry, and fish or their juices away from other food. Bacteria can spread through contact with the food or its liquid, causing cross-contamination.
  • Do not rinse raw meat or poultry because it can spread bacteria to nearby surfaces.
  • Wash all items you used for preparing raw foods, including utensils, cutting board, and plates, before using them for other foods or cooked meat.
  • Set aside a specific cutting board for preparing uncooked meat, fish, and chicken. Never use it for uncooked fruits, vegetables, or other foods.

Dispose of old food.

  • Eat canned and packaged food before its expiration date (the “use by” or “best before” date).
  • Consume refrigerated leftovers within 3 to 4 days. After that time, throw out the food. Even if the food does not smell or look spoiled, it still may be unsafe. Some bacteria, such as Listeria, can grow even on foods stored in the refrigerator if they are kept for too long.

Take precautions when eating out.

  • At restaurants, avoid buffets and salad bars where food sits out for a long time and comes in contact with many people. Food can become contaminated when someone with a virus, often a norovirus, or another “bug” handles it.
  • Put any leftover food in a “to-go” container yourself, rather than having the server do it. And, refrigerate leftovers as soon as you get home.
  • Choose restaurants that are clean and that are willing to prepare your food as you order it cooked.

Cook food to the right temperature. Use a food thermometer to check for a safe internal temperature of all poultry and meat. For instance, a hamburger should be cooked to at least medium (160˚F or 71˚C). Get a full list of recommended internal cooking temperatures on the website of the U.S. Food and Drug Administration (FDA).

Chill food promptly. Refrigerate or freeze perishable food within 2 hours of cooking or buying it (sooner in warm weather.) Proper cooking destroys bacteria, but they can still grow on cooked food that is left out too long. Food stored in the refrigerator should be kept at below 40˚F (4˚C). And, food stored in the freezer should be kept below 32˚F (0˚C).

Thaw food properly. Thaw frozen food in the refrigerator rather than at room temperature. You can also thaw food in frequently changed cold water or in the microwave, but cook it as soon as it thaws.

Think about your water source. Some water sources, such as well water, may contain potentially harmful bacteria or chemicals. Community-supplied tap water is fine for healthy individuals, but it is not tested for safety for people with weakened immune systems. Use a water filter to remove spores and cysts, as well as trace organics and heavy metals, for food preparation and drinking. Many types of these filters are for sale in stores.

Symptoms of foodborne illness

Symptoms of foodborne illness differ depending on the pathogen that causes the illness. Most often, symptoms are like those of the stomach flu:

  • Diarrhea
  • Stomach pain or cramps
  • Nausea
  • Vomiting
  • Fever
  • Headache
  • Muscle pains

The time symptoms begin can vary widely. It may be within a few hours to 10 days after eating the tainted food, or even later. With some foodborne illnesses, symptoms may not start until a few weeks later. Usually, however, people start feeling sick within the first couple days after infection.

When you suspect foodborne illness

  • Call your doctor right away. Early treatment is important.
  • Drink plenty of fluids to stay hydrated.
  • Keep the suspected food or the food’s packaging materials, as your doctor may want it to be examined.
  • If you became ill due to eating food at a restaurant or other public place, call your local health department. By reporting it, you may help prevent other people from getting sick.

More Information

Nutrition Recommendations During and After Treatment

When to Call the Doctor During Cancer Treatment

Additional Resources

U.S. Food & Drug Administration: Food Safety for People with Cancer

U.S. Department of Health & Human Services: Food Safety