Nutrition and cancer risk
Cancer research limitations
Cannot separate components of diet well. Data based on FFQ and diet hx intake is not extremely valid/reliable. Development of cancer is multifactorial, difficult to see nutrition picture clearly.
Reflux
Causes chronic inflammation and Barrett's Esophagus which predisposes to adenocarcinoma of the esophagus.
Cross-sectional study
Compares rates of cancer in a group with a key difference, i.e. comparing breast cancer in a state with high and low physical activity levels.
Case control study
Compares something about the case subject to a control subject. I.e. fruit in vegetable intake in a 62 y.o. white woman with cancer to a 60 y.o. white woman without cancer.
Brassica vegetables
Consumption is linked with reduction in breast cancer risk.
Animal studies
Control and experimental animals in the study. Inject substance that causes cancer into experimental, or use a transgenic animal bred to develop cancer. Then, provide different diets.
Fiber
Convincing evidence of a decreased risk for colo-rectal cancer according to a large epidemiological study.
Processed meat
Convincing evidence of increased risk for colo-rectal and gastric cancer. Limited suggestive increased risk for esophageal, lung, and prostate cancer.
Obesity
Convincing evidence that ____ increases risk for esophageal, pancreatic, kidney, liver, gall bladder, endometrial, post-menopausal breast, and colon cancer.
Alcohol
Convincing increased risk for mouth, pharynx, larynx, esophageal, breast, liver, and colo-rectal cancer. May protect against kidney cancer per 2015 data.
Obesity
Creates a systemic inflammatory environment. Adipocytes in central fat release pro-coagulant factors and adipocytokines that may increase risk for cancer.
American institute for cancer research
Recommends 5 portions (14 oz) non-starchy veg & fruits/d Eat relatively unprocessed cereals/legumes with each meal Limit refined grains No more than 18 oz red meat/wk, very little processed Limit salt
American Cancer Society
Recommends to eat at least 2.5 c. F & V/d, choose whole grains vs refined limit consumption of processed and red meats
Iron
Serves as a pro-oxidant, may facilitate cancer development.
Framinham Cohort Study
Showed that obesity and high waist circumference increased risk for cancer. Stronger effect in men than women.
Benefits of physical activity
-Promotes a healthy wt -Improves immune fxn -Positive influence on levels of sex hormones, insulin, and prostaglandins
Red meat
Convincing evidence of increased risk for colo-rectal cancer. Limited suggestive increased risk for esophageal, lung, pancreatic, endometrial cancer.
Fat intake
Could affect secondary bile acid content in the bowel and increase risk for cancer.
Initiation
Damage to DNA
Fruits
Limited suggestive decreased risk for nasopharynx, pancreatic, liver, and colo-rectal cancers. Probable decreased risk for mouth, pharynx, larynx, esophageal, and lung cancer.
Alcohol
May increase permeability of oropharynx tissues to carcinogens. May also increase circulating levels of estrogen and decrease folate levels which could influence development of breast cancer.
Vitamin D and calcium
4 yr RCT found that consumption of both was associated with improved survival free from cancer for a longer period of time.
Meet nutritional needs w/ diet vs supplements
AICR recommendations in regards to supplement use.
Molecular/cellular studies
Administer a substance to a specific type of cancer cells, then test for RNA, protein, or cell growth.
1. Maintain healthy wt and choose foods and bvgs to achieve/maintain healthy wt 2. Adopt physically active lifestyle 3. Consume healthy diet with plant sources. 4. Limit ETOH consumption
Advice to the public (4 main items).
Vitamin D
Associated with reduced risks of colorectal cancer but results are inconsistent. Unclear if associated with risk of other cancers. Not recommended for or against supplement to reduce risk of colorectal or any other type of cancer.
Promotion
Environment enhances reproduction of mutated cells
Indole-3-carbinol and sulforaphane
Exist as glucosinolates in brassica family vegetables and are hydrolyzed to these, which are anti-oxidants and natural detoxifying enzymes.
Omega 3 FAs
Fishermen on the coast had less cancer than farmers living inland possibly d/t consumption of this. However, conclusion is that dietary supplementation of this is not likely to reduce risk of cancer.
Soy
Incidence of breast cancer lower in Asian women who consume this regularly.
Women's Health initiative
Increased risk for invasive breast cancer in post menopausal women with a BMI >35.
Metabolic stress
Increases ROS, insulin levels, and adipokine secreation, along with gut permeability. R/t obesity.
Vegetables
Limited suggestive decreased risk for nasopharynx, esophageal, endometrial, ovary, colo-rectal cancer. Probable decreased risk for mouth, pharynx, larynx, and esophageal.
1. Achieve and maintain a healthy wt. Wt loss may be beneficial after treatment if over wt/obese. 2. Be physically active (esp for breast, colo-rectal, prostate, and ovarian cancer). 3. Eat a healthy diet, emphasize whole grains, fruits, and veg.
MNT for cancer survivors.
Progression
Mutated cells multiply rapidly, forming a tumor
Vitamin D and calcium
No effect on colorectal cancer in postmenopausal women according to the Women's Health Inititiative.
Vitamin C and Vitamin E
Physician's health study found no cancer benefit or harm from supplementing these 2 nutrients.
6 mos
Recommended time for breastfeeding to reduce cancer risk per AICR.
CPS II by Amer Cancer Society
Study showed that the heaviest men and women more likely to die from cancer.
Fruits and vegetables
Systematic review showed some decreased risk for lung cancer but not all data is convincing (some studies with no observed benefit).
Cohort study
Takes a population (group) and following them start to finish to identify who gets cancer and then look at difference in diet of those with and without cancer.
IGF-1
Thought to promote cell proliferation and survival, increased in obesity.
Tobacco, obesity, and physical inactivity
Three key lifestyle influences on risk for cancer. Over half of cancer deaths in U.S. in 2011 were caused by one of these risk factors.
Supplements
Until further research, it is wise to encourage public to reduce cancer risk by eating a variety of foods that provide many vitamins/minerals vs using these to reduce risk of cancer.
Physical activity
_______ has convincing evidence to decrease risk for colo-rectal cancer (15% of colo-rectal cancer can be attributed to lack of this!!!).