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Cancer and Nutrition
Overview
Cancer patients frequently have problems
getting enough nutrition. Malnutrition is a major cause of illness and
death in cancer patients. Malnutrition occurs when too little food is
eaten to continue the body's functions. Progressive wasting, weakness,
exhaustion, lower resistance to infection, problems tolerating cancer
therapy, and finally, death may result.
Anorexia (the loss of
appetite or desire to eat) is the most common symptom in people with
cancer. Anorexia may occur early in the disease or later, when the tumor
grows and spreads. Some patients may have anorexia when they are diagnosed
with cancer; and almost all patients who have widespread cancer will
develop anorexia. Anorexia is the most common cause of malnutrition and
deterioration in cancer patients.
Cachexia is a wasting syndrome
characterized by weakness and a noticeable continuous loss of weight, fat,
and muscle. Anorexia and cachexia often occur together. Cachexia can occur
in people who are eating enough, but who cannot absorb the nutrients.
Cachexia is not related to the tumor size, type, or extent. Cancer
cachexia is not the same as starvation. A healthy person's body can adjust
to starvation by slowing down its use of nutrients, but in cancer
patients, the body does not make this adjustment.
Some cancer
patients may die of the effects of malnutrition and wasting.
Effects
Effects of the Tumor
Many
malnutrition problems are caused directly by the tumor. Tumors growing in
the stomach, esophagus, or intestines can cause blockage, nausea and
vomiting, poor digestion, slow movement through the digestive system, or
poor absorption of nutrients. Cancer of the ovaries or genital and urinary
organs can cause ascites (excess fluid in the abdomen), leading to
feelings of early fullness, worsening malnutrition, or fluid and
electrolyte imbalances. Pain caused by the tumor can result in severe
anorexia and a decrease in the amount of foods and liquids consumed.
Central nervous system tumors (such as brain cancer) can cause confusion
or sleepiness; patients may lose interest in food or forget to eat.
Changes in the body's metabolism can also cause nutritional
problems. Tumor cells often convert nutrients to energy in different, less
efficient ways than do other cells.
Tumors may produce chemicals
or other products that can cause anorexia and cachexia. For example,
tumors can produce a substance that changes a person's sense of taste, so
that the patient does not want to eat. Tumors can affect the receptors in
the brain that tell the stomach if it is full. Tumors can also produce
hormone substances, which can change the amount of nutrients eaten, the
way they are absorbed, and the way they are used by the body.
Effect of Cancer Therapies
Nutrition problems can be
caused by cancer therapies and their side effects. The treatment may have
a direct effect, such as poor protein and fat absorption after certain
types of surgeries, or an indirect effect, such as an increased need for
energy due to infection and fever. Severe malnutrition is defined in two
ways: as an increased risk of illness and/or death and as a defined amount
of weight loss over a specified amount of time.
1. Surgery
Head
and neck surgery may cause chewing and swallowing problems or may cause
mental stress due to the amount of tissue removed during surgery. Surgery
to the esophagus may cause stomach paralysis and poor absorption of fat.
Poor absorption of protein and fat, dumping syndrome (rapid emptying of
the stomach) with low blood sugar, and early feelings of fullness may
follow stomach surgery. Surgery to the pancreas may also cause poor
protein and fat absorption, poor absorption of vitamins and minerals, or
diabetes. Small bowel and colon surgery may cause poor absorption of
protein and fat, vitamin and mineral shortages, diarrhea, and severe fluid
and electrolyte losses. Surgery to the urinary tract can cause electrolyte
imbalances. Other side effects of surgery that can affect nutrition
include infection, fistulas (holes between two organs or between an organ
and the surface of the body), or short-bowel syndrome. After a colostomy,
patients may decrease the amount they eat and drink.
2.
Chemotherapy
Chemotherapy can cause anorexia, nausea and/or vomiting,
diarrhea or constipation, inflammation and sores in the mouth, changes in
the way food tastes, or infections. Symptoms that affect nutrition and
last longer than 2 weeks are especially critical. The frequency and
severity of these symptoms depends on the type of chemotherapy drug, the
dosage, and the other drugs and treatments given at the same time.
Nutrition may be seriously affected when a patient has a fever for an
extended period of time since fevers increase the number of calories
needed by the body.
3. Radiation therapy
Radiation therapy to
the head and neck can cause anorexia, taste changes, dry mouth,
inflammation of the mouth and gums, swallowing problems, jaw spasms,
cavities, or infection. Radiation to the chest can cause infection in the
esophagus, swallowing problems, esophageal reflux (a backwards flow of the
stomach contents into the esophagus), nausea, or vomiting. Radiation to
the abdomen or pelvis may cause diarrhea, nausea and vomiting,
inflammation of the intestine or rectum, or fistula formation. Radiation
therapy may also cause tiredness, which may lead to a decrease in appetite
and a reduced desire to eat. Long-term effects can include narrowing of
the intestine, chronic inflamed intestines, poor absorption, or blockage
of the gastrointestinal tract.
4. Immunotherapy
Immunotherapy
(for example, biological response modifier therapy) can cause fever,
tiredness, and weakness, and can lead to loss of appetite and an increased
need for protein and calories.
Mental and Social
Effects
Eating is an important social activity. Anorexia and food
avoidance lead to social isolation when people cannot be with others
during meal times. Many mental and social factors can affect a person's
desire and willingness to eat. Depression, anxiety, anger, and fear are
often felt by cancer patients and can lead to anorexia. Feeling a loss of
control or helplessness can also reduce the desire to eat. Refusing to eat
even when begged to eat by family, friends, and care givers may be one way
a patient (who may not feel able to refuse treatment) feels able to have
some control in life. Learned food dislikes may also cause less eating or
drinking, nausea, and/or vomiting. People who have an unpleasant
experience after eating a certain food may avoid that food in the future.
Factors such as living alone, an inability to cook or prepare
meals, or an inability to walk to the kitchen because of physical
disabilities may lead to eating problems. A social worker or nurse can
evaluate the patient's home and recommend changes to help improve eating
habits.
Diagnosing the cancer and treating it often means that the
patient has to spend much time away from home and the normal routine,
including having meals. Favorite foods may not be available in the
hospital, or may not be tolerated well because of treatment side effects.
For example, a person who enjoys hot, spicy food and has inflammation of
the esophagus may not like the taste of bland food and may eat very
little. Changes in taste can affect a person's appetite and desire for
food.
The less a cancer patient eats, the weaker he or she
becomes, and the more it seems that the cancer is progressing. This
wasting is a constant reminder to the patient, family, and care givers of
the cancer diagnosis and expected poor outcome. This can affect quality of
life, social participation, and attitude. Also, with continued wasting,
and the resulting tiredness, the person socializes even less. Since food
and eating have such an important role in society, the inability to eat
well and the consequences of inadequate nutrition isolate the patient even
more.
Exercise (such as walking or mild aerobics) has a positive
effect on the patient's sense of well-being, alleviating nausea and
vomiting, and the patient's ability to eat. Patients who must have
artificial feeding methods may show depression, changes in body image, and
stress caused by feeding tubes and equipment. To cancer patients, problems
with nutrition are more important to their sense of well-being than their
sexuality and their ability to remain employed.
Nutritional Assessment
The patient's medical
history and physical examination are the most important factors in
determining the nutritional status of a cancer patient. This assessment
should include a weight history; any changes in eating and drinking;
symptoms affecting nutrition (including anorexia, nausea, vomiting,
diarrhea, constipation, inflammation and sores in the mouth, dry mouth,
taste/smell changes, or pain); medications that affect eating and the way
the body uses nutrients; other illnesses or conditions that could affect
nutrition or nutritional treatment; and the patient's level of
functioning. The cancer patient should be asked about changes in eating
and drinking compared to what is normal for him or her, and how long this
change has lasted. The physical examination should look for weight loss,
loss of fat under the skin, muscle wasting, fluid collection in the legs,
and the presence of ascites.
Finding out how much the person likes
to eat, as well as what he or she likes to eat, can help when making
changes to a cancer patient's diet. Knowing the patient's specific food
likes, dislikes, and allergies is also helpful.
General
Treatment Guidelines
The type of treatment needed to improve a
cancer patient's nutrition is chosen based on the following factors:
1. The presence of a working gastrointestinal tract.
2.
The type of cancer therapy, such as where and how much surgery has been
done, the type of chemotherapy used, where and how much of the body was
irradiated, the use of biological response modifiers, and the combinations
of therapies used.
3. The quality of life, how well the patient is
functioning, and the expected outcome of the cancer.
4. The cost
of the care.
Keeping the body looking well and maintaining good
nutrition can help the cancer patient feel and look better and help
improve his or her daily functioning. It may also help patients tolerate
cancer therapy. The type of treatment chosen for nutritional problems
depends on the cause of the problems. Problems caused by the tumor may end
when the tumor responds to therapy.
Food odor frequently causes
anorexia in cancer patients. Patients with anorexia should avoid odors
caused by food preparation. Cancer patients may be able to tolerate food
with little odor. For example, they may be able to eat at breakfast, since
many breakfast foods have little odor.
The following suggestions
can help cancer patients manage anorexia:
1. Eat small frequent
meals (every 1-2 hours).
2. Eat high-protein and high-calorie
foods (including snacks).
3. Avoid foods low in calories and
protein and avoid empty calories (like soda).
4. Avoid liquids
with meals (unless needed to help dry mouth or swallowing) to keep from
feeling full early.
5. Try to eat when feeling best; use
nutritional supplements when not feeling like eating. (Cancer patients
usually feel better in the morning and have better appetites at that
time.)
6. Try several different brands of nutritional supplements
or high- calorie, high-protein drinks or pudding recipes. If it tastes too
sweet or has a bitter aftertaste, adding the juice of half a freshly-
squeezed lemon may help.
7. Work up an appetite with light
exercise (such as, walking), a glass of wine or beer if allowed, or
appetite stimulants.
8. Add extra calories and protein to food
(such as butter, skim milk powder, honey, or brown sugar).
9. Take
medications with high-calorie fluids (like nutritional supplements) unless
the medication must be taken on an empty stomach.
10. Make eating
a pleasant experience (for example, try new recipes, eat with friends,
vary color and texture of foods).
11. Experiment with recipes,
flavorings, spices, types, and consistencies of food. This is important,
since food likes and dislikes may change from day to day.
12.
Avoid strong odors. Use boiling bags, cook outdoors on the grill, use a
kitchen fan when cooking, serve cold food instead of hot (since odors are
in the rising steam), and take off any food covers to release the odors
before entering a patient's room. Small portable fans can be used to blow
food odors away from patients. Order take- out food, to avoid preparing
food at home.
Suggestions for helping cancer patients manage taste
changes include:
1. Use plastic utensils if the patient complains
of a metallic taste while eating.
2. Cook poultry, fish, eggs, and
cheese instead of red meat.
3. Marinate meats with sweet marinades
or sauces.
4. Serve meats cool instead of hot.
5. Use
extra seasonings, spices, and flavorings, but avoid flavorings that are
very sweet or very bitter. A higher sensitivity to the taste of food may
cause them to taste flavorless or boring.
6. Substitute milk
shakes, puddings, ice cream, cheese, and other high protein foods for
meats if the patient does not want to eat meat.
7. Rinse the mouth
before eating.
8. Use lemon-flavored drinks to stimulate saliva
and taste, but do not use artificial lemon and use very little sweetener.
To prevent the development of taste dislikes:
1. Try new
foods and supplements when feeling well.
2. Eat lightly on the
morning of, or several hours before receiving chemotherapy.
3. Do
not introduce new tastes when bad odors are present.
To help dry
mouth or trouble swallowing:
1. Eat soft or moist foods.
2. Process foods in a blender.
3. Moisten foods with
creams, gravies, or oils.
4. Avoid rough, irritating foods.
5. Avoid hot or cold foods.
6. Avoid foods that stick to
the roof of the mouth.
7. Take small bites and chew completely.
The cancer patient should be encouraged to keep a positive
attitude towards treatment and try to take in enough calories and protein.
Individual calorie and protein requirements can be calculated so that
realistic goals can be set with the patient and his or her care givers.
The actual amount of calories and protein needed by each cancer patient
varies. The following formula can be used to determine how many calories
are needed to maintain a cancer patient's body weight:
General
guidelines of calories required (assuming light activity):
Underweight Adults - multiply weight in pounds by 18 Normal
weight adults - multiply weight in pounds by 16 Overweight adults -
multiply weight in pounds by 13
Some cancer patients need more
calories and protein. A cancer nutritionist (dietician, diet technician,
nurse, or doctor with special training in nutrition) can help determine
the nutritional needs and options of each patient. General guidelines for
grams of protein needed by cancer patients: multiply weight in pounds by
0.5.
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