The Importance of Protein During Radiation

4 months 3 weeks ago

In a previous blog, I discussed nutrition in cancer patients, especially concerning protein. Protein malnutrition is a devastating problem among cancer patients, as it increases morbidity, mortality, complications, length of hospital stay, hospital readmissions, and medical costs. It also diminishes patient quality of life and worsens patient outcomes. In short, the cost of protein malnutrition is large, not only financially, but can cause human suffering and may even lead to a patient’s death.

Unfortunately, the National Cancer Institute reported in Nutrition in Cancer Care-Health Professional Version, 2017 that protein-calorie malnutrition is the most common secondary diagnosis in individuals diagnosed with cancer. What is protein-calorie malnutrition? A condition caused by not getting enough calories, protein, or the right amount of key nutrients, such as vitamins and minerals that are needed for health. Generally speaking, most cancer patients experience some degree of gastro-intestinal (GI) dysfunction. The pain, inactivity, pain medication, surgery, chemotherapy, radiation and the disease, itself are causative factors. Protein-calorie malnutrition can and must be prevented.

Let’s specifically discuss radiation therapy and how it may relate to protein malnutrition. First, you need to know a few basics concerning radiation and its use in cancer patients.

Radiation therapy is used for almost 60% of cancer patients. It is a very valuable tool because radiation kills cancer cells by damaging their DNA. It’s used to treat patients by “de-bulking” or shrinking the tumor. Radiation may be used alone, or it may be used before surgery to shrink a tumor. This may make it easier for the surgeon to remove the tumor. Radiation may also be given during or after chemotherapy, with a goal of increasing its effectiveness. Radiation therapy can also be used as a palliative therapy to relieve symptoms. 

Unfortunately, while the radiation does damage to cancer cells, it may also harm normal cells. This is why some patients have side effects and complications from their radiation treatments. In some cases, these side effects significantly interfere with nutrition, and this may negatively affect patient outcomes and quality of life.

If radiation is part of your treatment plan, the side effects may occur early in treatment or even after treatment is complete. Side effects will also depend on the area being treated. Radiation therapy to the  brain, chest, head and neck, pelvis, rectum, and the stomach/abdomen are more likely to cause side effects that contribute to malnutrition. Side effects which may lead to malnutrition include fatigue, depression, anorexia, difficulty swallowing, mouth sores, change or loss of taste, dry mouth, oral infections, stiffness of the jaw, thick saliva, nausea, vomiting, and diarrhea. 

Since protein malnutrition is now recognized as the number one secondary diagnosis in cancer patients, I can’t overemphasize getting enough protein into your body beginning the day you are diagnosed. That being said, let’s briefly see what happens when you eat protein. Once in the mouth, the protein travels through the esophagus into the stomach. Here, stomach acid and enzymes are utilized to break down the protein into amino acids.

Protein degradation continues in the small intestine, facilitated by enzymes released from the pancreas. The resultant amino acids and peptides are then absorbed by the intestinal cells. Free amino acids are then released into the bloodstream for use by other tissues.  Every protein molecule has a role in maintaining body homeostasis. Protein makes up critical cell structure in muscle, viscera, blood cells, connective tissue and skin. Protein is also used in enzymatic activity, the immune system, and hormonal activity. Any loss of body protein is detrimental. Protein is necessary fuel for your body.

If a patient can’t eat enough protein or the patient’s body isn’t able to absorb the protein (malabsorption), then the patient is at risk for protein malnutrition and its potentially devastating outcomes.

Although radiation can affect any portion of the GI tract involved in therapy, such as the colon (radiation colitis) or rectum (radiation proctitis), let’s look at a condition called radiation-induced small bowel disease (also known as radiation enteritis or radiation enteropathy). This condition results from the normal cells of the intestinal lining being damaged by radiation. Malabsorption can be a very significant problem if the small intestine is affected. Symptoms may include abdominal pain, bloating, nausea, vomiting, and diarrhea. These symptoms usually begin around the second week of therapy and may last for several more weeks.

Chronic small bowel radiation disease may develop years after a completed course of radiotherapy. This may result in abdominal pain, nausea, vomiting, diarrhea, and weight loss. Additionally inflammation, ulceration, perforation, adhesions, bleeding, fistula formation, or stenosis/obstruction may occur. Occasionally, radiation vasculitis may be present. This means the blood supply to the intestine is compromised. These problems may resolve on their own or require additional treatment such as surgery. It has been reported that 90% of patients who receive pelvic radiation treatment develop a permanent change in their bowel habit, and 50% of patients with pelvic irradiation report decreased quality of life because of GI symptoms. While radiation therapy may not be painful during the actual administration, it is important for patients and their families to know the side effects and complications which may result. Talk to your healthcare team about your risk for side effects.

As radiation treatment has evolved, newer methods attempt to minimize damage to normal cells and decrease side effects. These methods include using the lowest dose of radiation as possible, spreading the radiation doses over time, and precise aiming of radiation to the cancer cells while sparing normal cells.

Remember, your body will use a great deal of energy to heal while undergoing any cancer treatment, including radiation therapy. It is of the utmost importance cancer patients do everything possible to take in sufficient calories, especially protein, to give themselves the best chance to maximize their treatment and return to wellness.



Steven L. Snodgrass, M.D., F.A.C.S.