04/19/23Oklahoma Cooperative Extension Service

Diet and Health Guidelines to Lower Risk of Cancer

Presented by Janice Hermann, PhD, RD/LD

OCES Adult and Older Adult Nutrition Specialist

CancerCancer second leading cause of death in the

United StatesCancer not a single disorder

Many typesDifferent characteristicsOccur in different body locationsTake different coursesRequire different treatments

Cancer DevelopmentGenes work together to regulate cell division

and ensure new cells are replicas of parent cells

Process allows:Body to growReplace dead cellsRepair damaged cells

Cancer DevelopmentCancer develops from mutations in genes

regulating cell divisionMutations inhibit genes that ordinarily monitor

and correct errorsAffected cells lose ability to stop cell division

Result is an abnormal mass of cells

Cancer DevelopmentAn abnormal mass of cells is called a tumor

BenignTumors that stop growing without intervention or can be

surgically removedMost often pose no threat to health

MalignantTumors that multiply out of controlThreaten surrounding tissues and health

How Cancer DevelopsAs a malignant tumor grows, blood vessels

form to supply the tumor with nutrients Eventually, the tumor invades more and more

healthy tissue and may metastasizeMalignant cancers are described by:

LocationSizeExtent of growthIf spread to surrounding lymph nodesIf spread to distant sites in the body

Cancer Development

Cancer DevelopmentGenetic FactorsImmune FactorsEnvironmental FactorsPhysical ActivityDietary Factors

Cancer InitiatorsCancer PromotersProtective Factors

Cancer DevelopmentGenetic factors

All cancers have a genetic component in that a mutation causes abnormal cell growth

Some cancers have a genetically inherited component as wellExample: someone with a family history of color cancer

has a greater risk of developing colon cancer than someone without a genetic predisposition; however, this does not mean that they will develop colon cancer

Cancer DevelopmentImmune factors

A healthy immune system recognizes foreign cells and destroys them

Theorized an ineffective immune system may not recognize tumor cells as foreign, thus allowing unchecked cell growthAging affects immune function, and incidence of cancer

increases with ageDiseases that weaken the immune system can increase

cancer risk

Cancer DevelopmentEnvironmental Factors

Environmental factors known to cause cancer:Exposure to radiation and sunlightWater and air pollutionSmoking

Cancer DevelopmentPhysical Activity

Lack of physical activity may play a role in the development of some types of cancerPeople whose lifestyles include regular, vigorous physical

activity have the lowest risk of colon cancerPhysical activity may also protect against breast cancer

by reducing body weight and by other mechanisms unrelated to body weight

Cancer DevelopmentDietary Factors

Estimates are 1/3 of cancers attributed to nutrition

Cancer InitiatorsSome dietary factors may initiate cancer development

Cancer PromotersOther dietary factors may promote cancer development

once it has startedProtective Factors

Still other dietary factors may protect against cancer development

Diet and Cancer StudiesEpidemiological studies try to identify relationships

between the diet of population groups and incidence of specific cancers

Diet complexity makes identifying relationships difficultThousands of chemicals in a dietDiets contain initiators, promoters and protective factorsChanging one factor in the diet may change others, making

identifying individual factors difficultMany cancers have a long latency period, thus diet at

initiation or promotion may not be the same as at diagnosis

Dietary Factors: Cancer InitiatorsPesticides

Some pesticides may be carcinogenic at extremely high doses, however, they are safe at the levels permitted on fruits and vegetables

The benefits of eating fruits and vegetables are far greater than any potential risk

Food additivesThose approved for use in foods are not

carcinogenic

Dietary Factors: Cancer Initiators

AlcoholAlcohol associated with increased risk of mouth,

esophageal and breast cancerMouth and esophageal cancer are especially increased if

alcohol is combined with smoking

Dietary Factors: Cancer Initiators

Alcohol If alcohol intake causes liver cirrhosis, there is an

increased risk of liver cancerMalnutrition associated with alcoholism is also

likely to be important in the increased risk for certain cancers

Thus, potential benefits of moderate alcohol intake for cardiovascular disease must be weighed against potential risks

Dietary Factors: Cancer InitiatorsFood preparation methods

Cooking meat, poultry, and fish at high temperatures and smoking meat causes carcinogens to form on food surfaces which have been related to colon, breast and stomach cancerHigh heat cooking methods such as grilling, broiling, and

barbecuing Healthier cooking methods include roasting,

broiling, poaching, steaming, stewing, braising and microwaving

Fruits and vegetables appear to provide a protective effect

Dietary Factors: Cancer InitiatorsFood preparation methods

Large amounts of salt-cured and salt-pickled foods have been related to stomach, colon and bladder cancersSodium and potassium nitrates used in salting, pickling,

and curing processesNitrates can be converted into nitrite, which can form

potential carcinogens nitrosamines Diets with high amounts of fruits and vegetables

contain vitamin C and phytochemicals can retard conversion of nitrites to nitrosamines

Dietary Factors: Cancer Promoters

High fat dietsHigh dietary total fat and saturated fat may be

related to increased risk of breast, colon, endometrial and prostate cancerOmega-3 fatty acids however, may be protective

Thus same dietary fat advice applies to cancer protection as to heart diseaseReduce total fat and saturated fatIncrease omega-3 fatty acids

Dietary Factors: Cancer Promoters

High fat dietsMay increase cancer risk by increasing:

ObesityBile acid productionEstrogen levels

Because fat is calorie dense it is difficult to distinguish between the effects of high dietary fat, and total calories

Dietary Factors: Cancer Promoters

High calorie intakeIn most epidemiologic studies, a positive

association has been seen with high calorie intake and promotion of breast, colon and endometrial cancer

Increased risk may be due to:Excess calories themselvesWeight gain due to excess caloriesHigh fat intake that often supplies excess calories

Dietary Factors: Cancer Promoters

Obesity may increase risk of colon, endometrial and breast cancerIncreased risk may be due to:

Extra weightAdipose tissue production of estrogenExtra caloriesHigh fat intake that often supplies excess calories and

contributes to weight gainProtective effect of physical activity related to

breast and colon cancer may be due in part to helping to control obesity

Dietary Factors: Cancer PromotersProtein

Excessive muscle meat sources of protein have been related to increased risk of colon and prostate cancer

Not know if increased risk due to:Protein levelFat contentFat typeIncreased calories from fatOther factor such as being low in fiber, antioxidants and

phytochemicalsFurther research needed

Dietary Factors: Cancer PromotersProtein

In general tumor development is:Suppressed by diets that contain protein below that

required for optimal growthEnhanced by protein levels two to three times the

amount required

Dietary Factors: Protective Factors Fruits, vegetables, whole grains and legumes

Epidemiological studies show a link between diets with plenty of fruits, vegetables, whole grains and legumes and reduced incidence oral cavity, esophagus, stomach, colon and lung cancer

Compounds in these foods that may help lower cancer risk:Dietary fiberVitamin CVitamin EPhytochemicalsLow fat

Dietary Factors: Protective FactorsFruits, vegetables whole grains and legumes:

FiberFiber-rich diets may protect against colon cancer

In the intestine bile can be converted into potential cancer causing substances. Soluble fibers can bind bile acids and increase their excretion

Insoluble fibers absorb water making a larger, softer stool which can dilute potential cancer causing substances

A larger, softer stool moves through intestine faster so colon exposed to cancer causing substance for less time

Foods high in fiber are typically lower in fat, which may also help protect against colon cancer by reducing bile acid production

Dietary Factors: Protective FactorsFruits, vegetables, whole grains and legumes:

Antioxidants Fruits, vegetables, whole grains and legumes also

contain antioxidant nutrients that may protect against cancerAntioxidants stop free radical oxidation which may help

to prevent cell and tissue damage that can promote cancer

Possible these nutrients have many other effects in the body which lower cancer risk

Dietary Factors: Protective FactorsFruits, vegetables, whole grains and legumes:

PhytochemicalsFruits, vegetables, whole grains and legumes also

contain phytochemicals that may protect against cancerSome function antioxidants, protecting against harmful

cell damage from oxidationOthers lower cancer risk in different ways such as

activating enzymes that destroy carcinogens

Dietary Factors: Protective Factors

Fruits, vegetables, whole grains, and legumesBecause it is not known which specific substances

in fruits, vegetables, whole grains and legumes help to lower cancer and whether it is the substances themselves or their presence in food, the best recommendation is to eat a variety of these foods.

Best to get these nutrients from foods not supplements.

Dietary Factors: Protective Factors

CalciumCalcium may have a role in lowering colon cancer;

however, more research is neededIn the meantime, adequate calcium is known to

be important for growth and bone development

Cancer Development

Evidence suggests millions of cases of cancer could be prevented by changes in:DietWeight controlPhysical activitySmoking

Consequences of CancerNonspecific effects of cancer include:

Anorexia and reduced food intakeMetabolic alterationsTissue wasting and weight loss

Anorexia, tissue wasting, weight loss and fatigue typify cancer cachexiaOccurs in as many as 80% of people with cancer

Consequences of CancerAnorexia and Reduced Food Intake

Major contributors to wastingWith cancer body may not be able to respond to

reduced nutrient intake and nutrient stores are rapidly depleted

Without adequate energy and nutrients, the body is poorly equipped to:Maintain immune defensesSupport organ functionAbsorb nutrientsRepair damaged tissues

Consequences of CancerAnorexia and Reduced Food Intake

Factors contributing to anorexia and reduced food intake:Chronic nausea and early satiety

People with cancer frequently experience nausea and a premature feeling of fullness after eating small amounts of food

FatiguePeople with cancer often tire easily and lack the energy to prepare

and eat meals If cachexia develops, these tasks become even more difficult to

handle

Consequences of CancerAnorexia and Reduced Food Intake

Factors contributing to anorexia and reduced food intake:Pain

People in pain may have little interest in eating, particularly if eating makes pain worse

Mental stressA cancer diagnosis can cause distress, anxiety, and depression, all

of which may reduce appetiteFacing and undergoing cancer treatments causes additional

psychological stress

Consequences of CancerAnorexia and Reduced Food Intake

Factors contributing to anorexia and reduced food intake (cont.):Effects of cancer therapies

Therapies for cancer (including medications, chemotherapy radiation therapy, surgery, and bone marrow transplants) can affect food intake by causing nausea, vomiting, altered taste perceptions, food aversions, inflammation of the mouth and esophagus, dry mouth, mouth sores, difficulty swallowing, intestinal cramping, diarrhea, and constipation

Consequences of CancerAnorexia and Reduced Food Intake

Factors contributing to anorexia and reduced food intake (cont.):Obstructions

A tumor may partially or completely obstruct a portion of the GI tract, causing complications such as nausea and vomiting, early satiety, delayed gastric emptying, and bacterial overgrowth

Some patients with obstructions are unable to tolerate oral diets

Consequences of CancerMetabolic Alterations

Metabolic changes can also exacerbate wastingIncreased protein turnover, but reduced muscle protein

synthesisIncreased gluconeogenesis, further straining supply of body

proteinsIncreased triglyceride breakdown, but decreased fat synthesisMany develop insulin resistance

Metabolic alterations help explain why people with cancer fail to regain lean body mass or maintain healthy body weights even when receiving adequate energy and nutrients

Consequences of CancerTissue Wasting

Weight loss often evident at time cancer diagnosedFactors contributing to wasting

Anorexia and reduced food intakeMetabolic alterationsCytokines released by both tumor and immune cells

induces a hypermetabolic, catabolic stateDiversion of nutrients to support tumor growth result in

lower energy and nutrients available to healthy tissuesSevere tissue wasting, often seen in the later stages

of cancer, may be ultimate cause of death

Cancer TreatmentsPrimary medical treatments for cancer are:

SurgeryChemotherapyRadiation Therapy

Aim is to remove cancer cells, prevent further tumor growth, and alleviate symptoms

Medical treatments can effect nutritional status

Cancer TreatmentsSurgery

Performed to remove tumorsCan affect nutritional status

Acute metabolic stress caused by surgery raises protein and energy needs and can exacerbate wasting

Surgery may also contribute to pain, fatigue, anorexia and reduced food intake

Blood loss further contribute to nutrient losses

Cancer TreatmentsChemotherapy

Used to inhibit tumor growthInterfere or prevent cell divisionAffect rapidly growing cancer cells

Unfortunately, most of these drugs can effect normal cells (especially rapidly dividing cells, such as those in the GI tract, skin and bone marrow) and can effect nutritional status due to:AnorexiaNauseaMalabsorptionDiarrhea

Cancer TreatmentsRadiation Therapy

Bombarding cancer cells with radiation induces formation of reactive oxygen species, such as superoxide and hydroxyl radicals, which can damage cellular DNA and cause cell death

Radiation can effect normal cells and can effect nutritional status Radiation to head and neck may damage salivary glands and

taste buds, causing dry mouth and altered tasteRadiation to lower abdomen can cause radiation enteritis,

inflammation of the small intestine, causing nausea, vomiting, diarrhea, and malabsorption

Cancer TreatmentsBone Marrow Transplants

Replace bone marrow destroyed by chemotherapy or radiation

Primary treatment for leukemiaCan substantially effect nutritional status

After bone marrow is destroyed, immune function is suppressed, increasing the risk of foodborne illness

Effects of transplant include anorexia, dry mouth, inflamed mucous membranes, altered taste, and diarrhea

Patients often unable to consume adequate food and may require nutritional support

Cancer TreatmentsMedications to combat anorexia and wastingMedications sometimes prescribed to

stimulate the appetite and promote weight gain

Cancer TreatmentsAlternative therapies

60 to 80% of cancer patients combine complementary and alternative medicine (CAM) approaches with standard treatment

Many people do not discuss their use of complementary and alternative medicine approaches with their physicians

Cancer TreatmentsAlternative therapies

Dietary supplements and herbal remedies among most frequently used CAM

Many supplements can be used without risk; however, others may have adverse effects or interfere with conventional treatmentsSt. John’s wort can reduce effectiveness of some

anticancer drugsAntioxidant supplementation may interfere with

chemotherapy and radiation treatment

Nutritional TherapyObjectives of medical nutrition therapy are to:

Minimize tissue wasting and weight lossProtein and energy needs are considerable to prevent

tissue wasting and weight loss.Correct nutritional deficienciesHelp people maintain their strength and immune

functionProvide a diet that can be tolerated and enjoyed

despite the complications of illness

Nutrition TherapyNutrition therapy depends on the type and

severity of cancer, side effects of treatment and patient’s nutritional status

In addition, factors may interfere with eating

Nutrition TherapyEnteral (tube) and parenteral (intravenous) nutrition

supportTube feedings and intravenous nutrition not routinely

recommended for adequately nourished or mildly malnourished people with cancer who are able to eat

However, these approaches help to maintain nutrition status when anorexia persists or when a patient is severely malnourished and is about to undergo aggressive cancer therapy

Each case is decided individually

Nutrition TherapyNutrition support for bone marrow transplants

People undergoing a bone marrow transplant routinely receive total parenteral nutrition (TPN) before and after the transplant because the GI tract is severely compromised by the preparatory procedure

When GI function return, the patient begins to receive foods orally along with TPN, whenever possible

As oral intake improves, TPN is gradually tapered off