2: Prevention

Question 1

What Cancers have convincing evidence that greater adiposity is a cause/risk?

Answer 1

esophagus(adenocarcinoma), pancreas, colorectum, breast(postmenopausal), endometrium, liver, and kidney

Question 2

What cancers have probable evidence that greater adiposity is a cause/risk?

Answer 2

stomach (cardia), gallbladder, ovaries, mouth/pharynx/larynx, and possibly prostate

Question 3

What are the possible mechanisms for the excess body fatness being a risk factor?

Answer 3

Insulin resistance=increase of IGF-1=increase promotion of growth and proliferation of cancer cells and inhibit apoptosis

chronic low-grade systemic inflammation=promote heightened local inflammation and cancer development

Increase bioavailability of estrogen, increasing endometrial and postmenopausal cancer risk

Increased levels of leptin=activate signaling that promotes cell proliferation and angiogenesis. Leptin can also induce aromatase enzyme required for adipose estrogen production

Deceased levels of adiponectin, which is a cancer protective hormone

Question 4

What are the levels for waist circumference recommended to reduce cancer risk?

Answer 4

Should be no larger than 37” in men and 31.5” in women

Question 5

Ways Physical Activity can reduce cancer risk

Answer 5

improved weight/body fat
improved insulin sensitivity and insulin levels
decreased levels of bioavailable sex steroid hormones
more rapid gut transit time, reducing colon cells exposure to carcinogens
improved immune function

Question 6

A Plant-based diet is recommended due to several studies. They show cancer risk reduction via:

Answer 6

Phytochemicals - inhibit phase I carcinogen-activating enzymes (cytochrome P-450) and promote activity of phase II carcinogen-detoxifying enzymes (glutathione S-transferase).

Epigenetic effects - several plant based foods can either silence or promote gene expression such as tumor suppressor genes

Hormone levels – increase fiber can reduce glucose absorption, reducing insulin levels

Antioxidant effects - reducing the effect of free radials

Gut Microbiota - fiber helps promote butyrate, which promotes healthy colon cell development

Question 7

Reasoning behind Red/Processed Meats reduction recommendation and levels

Answer 7

Red - 12-18 oz/week ; processed - little, if any
Risk for colorectal cancer increases by 12% for every 100 g red meat consumed daily and by 16% for every 50 g processed meats consumed daily

Red meat - heme iron, increased free radicals. also promotes formation of carcinogenic N-nitroso compounds (NOC) in gut
NOCs also form when nitrates are used to preserve meat are combined with amines from amino acids (during the curing process or in the digestive tract)
Cooking meat at high temp - increases production of heterocyclic amines and polycyclic aromatic hydrocarbons, both are carinogenic
gut microbiota might convert protein residues in high meat diets into carcinogenic/proinflammatory or both substances

Question 8

What cancers is alcohol consumption linked to?
What are the mechanisms?
What are the recommendations for consumption?

Answer 8

mouth, pharynx, larynx, esophagus (squamous cell), liver, stomach, colorectal, and breast (both pre and post)

Ethanol converts to acetaldehyde(carcinogen), it is solvent-enhancing penetration of dietary carcinogens–even worse with tobacco, metabolism generates reactive oxygen that can damage DNA, and increases circulating estrogen

14 g ethanol is one standard drink – limit to 1/day for women, 2/day for men. 14 g = 5 oz wine, 12 oz beer, 1.5 oz liquor

Question 9

Pros and Cons of Calcium Supplementation

Answer 9

doses above 200 mg/d PROBABLY protect against colorectal
limited evidence suggests diets high in calcium (food and supplements) increase risk of prostate cancer

Question 10

What supplements are associated with increased cancer risk?

Answer 10

High-dose B-carotene – increased lung
High-dose Vitamin E – may promote modest risk for prostate

Question 11

General rule for supplements

Answer 11

Research supports supplementation in a nutrient if a person is below normal/adequate levels, but it may have no effect or even be harmful to supplement when levels are already good.

This goes against the public’s practice of “if a little is good, more is better” with antioxidants and nutrients

Question 12

Flaxseed recommendations

Answer 12

Although there is no clear recommendation, 1-4 Tbsp/day ground flaxseed does have some evidence to be safe and possibly lower risk of breast and other cancers

Some observational studies found no link of interference of flaxseed consumption and the effectiveness of Tamoxifen

Very little studies done for Prostate, but might lower tumor biomarkers or presurgery rates of cell proliferation