Cancer Essay Flashcards
What does obesity increase and what is the consequence for cells (4)
Increase production of pro-inflammatory cytokines, sex steroids and insulin-like growth factor 1
Results in chronic low grade inflammation
Chronic low grade inflammation consequence on cells (2)
Promotes proliferation of tumour cells an discourages apoptosis
Lifestyle factors that lead to obesity and are also associated with cancer (4)
Low physical activity
High meat intake
Low fruit and veg intake
Low fibre intake
How may physical activity protect against colorectal cancer?
Reduction of insulin resistance
Oesophageal cancer and obesity
Promoted by gastric reflux in obese individuals
Fibre cancer intro
World cancer research fund has reported a 10% decreased risk in colorectal cancer per 10g/day
Fibre protective mechanisms (4)
Larger stool size and smaller surface area to volume ratio exposes fewer caring end to the colon
Larger stools result in a reduced transit times
Less carcinogens spend less time in the colon
Products of bacterial fermentation produces anti-tumour agents
Albert fibre supplement intervention (3)
Study on men who previously had colorectal tumour removed
High fibre supplementation compared against low fibre supplement
However there were no benefits of fibre supplements
Folate or fibre debate (4)
Studies that have reported a reduced risk have come from dietary sources
Therefore no effect can be attributed specifically to fibre
Fibre intake is strongly correlated with folate intake
Studies have shown that serum folate is associated with a lower risk for colon cancer but not rectal cancer
Folate cancer mechanism (4)
Plays an important role in DNA synthesis, methylation and repair
Abnormal methylation has been linked to abnormal gene expression
And cancers at several sites
Folate may also reduce HPV proliferation in cells
Red meat cancer relationship
Meta-analysis of cohort studies showed a 15% increased risk per 50g/d
Red meat cancer mechanism (4)
Generation of potentially carcinogenic N-nitroso compounds
Some meats are cooked at high temp results in the production of heterocyclic amines
And polycyclic aromatic hydrocarbons
Red meat contains haem iron and free iron can lead to the production of free radicals
Epic study fibre cancer (3)
Largest study ever conducted
On the relationship between diet and cancer
Findings suggest that dietary fibre is protective
Non nutrient components of plant foods that may be protective against cancer (5)
Flavonoids Isothiocynates Allium Indoles Phenols
Plant foods protection apart from fibre (2)
Some fruit and veg are high in fibre
However they are also high in other components that may protect against cancer
CARET trial (3)
Examined the effects of carotene and retinol supplementation ok lung cancer risk
Trial was stopped early due to no benefit and increased mortality
Excess beta carotene promotes cell proliferation if initiation has already occurred
Plants and antioxidants (4)
Strong evidence that foods which are rich in antioxidants are protective against many cancers
E.g green leafy veg and citrus fruits
Harder to establish if the benefits are specifically due to antioxidants
Issues with interventions (4)
Extremely high doses
Fail to promote dietary behaviour
Lack of considerations of the interactions between nutrients
Lack of consideration of the non nutrient components of fruit and veg
African Americans v rural Africans intro oKeefe (5)
Intake from animal products much higher in African Americas than rural Africans in SA
While fibre intake much high in RAs
Colon cancer is also much more prevalent in AAs then RAs
This suggest dietary factors play a role in cancer risk
It’s been observed that AAs have greater mucosal proliferation
Which is a biomarker of cancer risk
AAs v RAs intervention (4)
AAs fed high fibre low fat African style diet
Dietary change resulted in marked changes in mucosal biomarkers of cancer risk
Such as increased bacterial fermentation
And suppressed secondary bike acid synthesis
Bjelakovic antioxidant meta analysis (2)
Conducted a meta analysis examining the effects of antioxidant supplements on GI cancer
The results from high quality studies found a significantly greater risk of death from AOX supplants
Obesity and breast cancer (3)
Premenopausal women at less risk with high BMI
Postmenopausal women at more risk with high BMI
Central adiposity increase risk in all women
Obesity breast cancer mechanism (3)
Beyond menopause production of progesterone and oestrogens stops
Increase in androgens
Androgen converted to most carcinogenic oestrogen (17b-oestradiol) in adipose tissue
Strong correlation between oestradiol and BMI Postmenopausal
Isothiocynates protective mechanism (3)
Activate phase II metabolism
Of the metabolism of carcinogens
This results in the removal of carcinogens
