Cancer Development and Diagnosis Flashcards
How many people get cancer each year? Which cancer is most prevalent
42,000- 26% is skin cancer
Write a note on smoking as a cancer risk
in the USA it accounts for 17% of deaths and 30% of cancer. Passive smoking is also a huge risk- non-smoker living with a smoker has 30% higher risk of dying from lung cancer
Lung cancer from smoking = increased risk of cancer in the mouth, oesophagus, pharynx, kidney and bladder
how many carcinogens are in tobacco
over 40- such as benzopyrene and nitrosamines such as dimethylnitosamine
how many years between tobacco consumption and lung cancer changes?
20 year gap
what effect is described to increase the risk of mouth cancer when alcohol and smoking are consumed together?
synergistic effect
what is a free radical
an atom, molecule or ion with unpaired electrons- they are highly reactive and take part in chemical reactions
They take part in biological reactions such as the killing of bacteria by Neutrophils
Reactions between free radicals and DNA are thought to cause many malignant cancers
which free radicals may participate in unwanted side reactions to produce cell damage?
superoxide and hydroxyl radicals
what enzymes are used to control the amount of free radical induced cell damage?
superoxide dismutase and glutathione peroxidase
what effect do antioxidants have on free radicals?
they neutralise certain free radicals- vitamins A, C, E and polyphenols
what effect does a good diet have on cancer risk?
fruit and veg are protective against many cancers (gastrointestinal, breast and lung). fruit and veg have fibre, complex phenols + micro-nutrients such as carotenoids and Vit A,C,E
what diet is considered to be the best diet?
Mediterranean diet- lots of fruit and veg, red wine for phenols and complex carbs with low saturated fats
what are 2 features of carotenoids that allow them to be a good preventative measure against cancer
1.they are rich in antioxidants
2. they are a precursor of vit A which promotes cell differentiation and hinders cell proliferation
What forms of vit A, C, E are found in food
Vit A = retinol
Vit C = ascorbic acid
Vit E = tocopherol
These all have antioxidant properties
what are the two types of plant phenols
Lignans- metabolised by gut micro-flora into phenols
Isoflavones- are found in soya products with oestrogen-like receptors. This has a beneficial effect on cancers requiring sex hormones for genesis as the phenols antagonise the mitogenic effect of the natural sex hormone oestradiol
how does fibre help prevent cancer
mode of action is unclear, but it is thought it may help:
1. inactivate carcinogens
2. alter the profile of the gut
3. high fibre diet is often associated with a low fat diet
two areas with similar fat intake but diff fibre intake were compared - New York had high fat low fibre and Finland had high fat but high fibre intake - finland had lower colon cancer incidence
what is the relation of fat and meat to cancer?
high meat diet is linked with high colon cancer rates. Meat is a major source of animal fat in Western diets. Animal fat has saturated fatty acids + cholesterol. high fat consumption esp of animal origin increases cancer risk at many sites
what relation is between obesity and cancer?
Obesity results in the production of the mitogenic steroid oestradiol as fat cells synthesis it - which triggers proliferation
what cancer is influenced by a high salt intake
stomach cancer
what does selenium and calcium do for cancer
they have protective effects
which cancers are influenced by increased alcohol intake
breast, colon, liver, upper digestive tract
what influence have sex hormones on cancer risk
these are a factor in prostatic cancer in men, and breast + ovarian cancer in uterine in women. Male + female hormones influence proliferation of respective target cells.
low fat diet in men = lowered testosterone so lowered prostate cancer risk.
Obesity in women = increased oestrogen so increased proliferation
what is used to treat breast cancer
anti-oestrogen therapies, i.e tamoxifen
whats the relationship between family history and cancer
there is some genetic association with cancer- does not account for more than 10 % of cancers
some rare childhood cancers such as retinoblastoma or wilms tumour (kidney) are affected genetically
name some chemical agents that are known to cause cancer
Radon-222 (lung), X-ray (breast, thyroid, bone), Asbestos (lungs), HPV (cervix)
what viruses may cause cancer?
Hep B and C in liver, HPV in cervix, Human Immunodeficiency (sarcoma), Human T-cell lymphotrophic (leukaemia)
