Topic 5 - Diet & Cancer (PART B) Flashcards
What are benign tumours?
cancer cells that do not spread beyond the immediate area in which they arise - are not dangerous
become malignant when they start to spread into surrounding areas
What are oncogenes?
An oncogene is a mutated gene that has the potential to cause cancer. Before an oncogene becomes mutated, it is called a proto-oncogene, and it plays a role in regulating normal cell division.
What is a tumour suppressor gene?
normal genes that slow down cell division or tell cells to die at the right time (a process known as apoptosis or programmed cell death).
when tumor suppressor genes don’t work properly, cells can grow out of control, which can lead to cancer.
they also repair mismatched DNA
What are sporadic cancers?
cancers that occur because of acquired mutations
- are the most common causes of cancer
What are germline mutations (inherited cancer)?
passed directly from a parent to child (found in every cell of body)
Examples of tumour suppressor genes
BRCA1, BRCA2, p53
When a tumour suppressor gene is mutated, what happens?
cells grow uncontrollably and may eventually form a mass called a tumour
What are 2 common oncogenes?
HER2 –> specialized protein that controls cancer growth and spread - found on some cancer cells (e.g. breast and ovarian cancer cells)
The ras family of genes –> make proteins involved in cell communication pathways, cell growth, and cell death
What are oncogenic viruses?
they transfer their genetic material to other cells and then remain in the body for a long time as a latent infection
What is one characteristic of oncogenic infections?
- they encourage cells to reproduce at an unusually fast rate, which may damage the genetic material in those cells
-
Examples of oncogenic infections
- hepatitis B or C (damage the body slowly, over many years)
- Epstein-Barr virus
Why does cancer develop in some people who have had oncogenic infections but not others?
because other factors, such as smoking or exposure to other carcinogens, may be needed to trigger the final change of a normal cell into a cancer cell
also each person’s individual genetic makeup can differ
What is the difference in presence of infectious agents in developed and less-developed countries?
22.9% vs 7.4%
What is one important advance in cancer prevention in the past decade?
- the development and implementation of HPV vaccination to prevent cervical cancer
- a priority should be to ensure that the vaccine reaches the populations with the highest prevalences of HPV infection and cervical cancer
Reduced exposure to occupational carcinogens, like aromatic amines or asbestos, have led to reductions in . . .
mesothelioma risk
bladder cancer
Preventative recommendations (Word Cancer Research Fund and American Institute for Cancer Research)
- be lean
- be physically active
- eat a variety of fruits, veg, wholegrains, pulses
- limit alcohol consumption
- don’t smoke
Don’t eat foods high in. . .
ENERGY
Compliance with the WCRF recommendations has been associated with. . .
- a reduction in overall cancer risk (5%)
- with larger reductions for colorectal (12%) and stomach (16%) cancers
Epidemiological evidence suggests that fruit & veg offer only _____ to limiting total cancer burden, mainly limited to cancers of the digestive tract
a modest contribution
What are some important areas of research?
- improvement in methods used to assess diet
- consideration of diet throughout life course
- an analysis of how the host microbiome and genome interacts with dietary patterns and nutrients to modulate riske
What are some important but uncertain areas of potential public health importance (environmental carcinogens)?
- non-occupational exposure to pesticides
- effect of electromagnetic fields
Why is a reductionist approach to dietary studies ineffective?
- we shouldn’t focus on specific nutrients
- we should focus on the complex interactions bw genetic, epigenetic, metabolic, and gut-microbial processes that will inform our knowledge of the diet-cancer relationship
Estimates suggest that only
_____ of a person’s lifetime risk of getting cancer results from uncontrollable factors
less than 30%
What 4 lifestyle areas did the Harvard researchers examine?
- smoking
- drinking
- weight gain
- lack of exercise
What did the Harvard study find?
- found that men could delay 67% of cancer deaths and prevent 63% of new malignancies each year by having a good lifestyle
- could reduce bladder cancer, prostate cancer, kidney cancer
GI study - what was found?
consuming foods with a high GI (70 or higher) was associated with an 88% greater risk for prostate cancer
low GI foods (beans, lentils, peas) = 32% lower risk of both prostate and colorectal cancer
What are some examples of high GI foods?
soft drinks
fruit juices
processed foods like pizza
High dietary GI and high carbohydrate intake from high GI foods are associated with. . .
an increased risk of COLORECTAL cancer
What was found in the Dutch study?
A major risk factor was inadequate dietary fibre intake and inadequate fruit and veg consumption will contribute more
The International Agency for Research on Cancer classifies _____ meat as a cause of cancer, and _____ meat as a probable cause of cancer
processed
red
small effect for both generally
How might red & processed meat cause cancer?
Red and processed meat contains a red pigment called haem, which could irritate or damage the cells in the body
the cells divide much more than normal to compensate for this damage
this increases the chance that one of the cells could acquire changes that cause cancer
Haem could stimulate the bacteria in our guts to produce chemicals called N-nitroso compounds
Why are nitrates and nitrites added to processed meat?
- to preserve the meat
- nitrite and nitrates can be converted into N-nitroso compounds during the curing process & in the body
High-fat diets COULD promote carcinogenesis via _______ ?
insulin resistance
The cancers associated with high meat consumption could be reduced through a number of ways. List a few
- by addition of anticarcinogens in the diet esp at the same time as meat prep or meat consumption
- the modification of food preparation methods
What are potential anticarcinogens found in meats?
- omega-3 PUFA
- conjugated linoleic acid (CLA)
- selenium
- vitamin B6 & B12
- vitamin D
