Risk factors and the cause of cancer

Question 1

How many people are estimated to develop some form of cancer during their lifetime in the UK?

Answer 1

1 in 3 people

Question 2

What are the 5 independent and modifiable risk factors for cancer?

Answer 2

1) Smoking
2) Alcohol
3) Obesity
4) Sedentary lifestyle and lack of exericse
5) Sunlight

Question 3

Outline the impact of smoking on health and it’s specific risk to cancer

Answer 3

• Single biggest cause of cancer in the world accounting for a quarter of all UK deaths
• Killed an estimated 6 million people in the UK over past 50 years - five times more than road accidents, overdoses, murder, suicide and HIV all put together
• Causes 9 in 10 cases of lung cancer
• Stop smoking 10 years risk for LC falls to half and risk for heart attack after 15 is same for those who has never smoked
• 80 of the 4000 chemicals in tobacco smoke pose a risk for cancer
• Chemicals with strongest link: Formaldehyde, 1,3-butadiene, arsenic, benzene and cadmium - when inhaled they enter lungs and spread throughout
• 50% of regular smokers die from their habit and half of these will be middle aged (35-69)

Question 4

What are the primary cancers caused by smoking?

Answer 4

• Mouth, larynx, parynx, nose and sinus, oesophagus, liver, pancreas, stomach, kidney, bladders, cervix and bowel, one type of ovarian cancer and some leukaemias.

Question 5

What types of cancer are most strongly associated with alcohol?

Answer 5

• Mouth, Pharynx, Oesophagus, Larynx, Breast, Bowel and Liver

Question 6

Outline the relationship between alcohol and health, specifically cancer?

Answer 6

• Causes 6% of cancer related deaths (UK)
• All alcohol is carciogenic even in small amounts (no such thing as safe amount)
• One unit increases risk of breast and bowel
• Three units increases risk: mouth, throat, oesophageal and pharynx cancers - drinking and smoking together further increases risk of these cancers
• Risk of alcohol is limited if you have:
  One small drink for women (roughly one unit)
  Two small drinks for men (roughly two units)
• Two alcohol free days each week

Question 7

What cancers are strongly linked with being overweight or obese?

Answer 7

• Endometrial, Kidney, Oesophagus and first part of stomach, colon, gallbladder, pancreatic, postmenopausal breast cancer

Question 8

What cancers does obesity impact the most?

Answer 8

• Endometrial - quadruples risk

- Post-menopausal breast cancer - 30%

Question 9

What are the mechanisms behind obesity induced cancer?

Answer 9

• Alters balance of sex steroid hormones
• Higher insulin and insulin-like growth factor (IGF) activity
• Elevated concentrations TNF-a, IL-6 and C-reactive protein

Question 10

How does colon cancer change with obesity?

Answer 10

• 25% increase risk in overweight
• 50% increase risk in clinically obese
• 50% increase risk in predominantly central fat

Question 11

What was found in the European prospective investigation of cancer (EPIC) study

Answer 11

• Obese men have higher risk of bowel cancer

- Diet high in fibre and low in processed meat reduces risk of bowel cancer

Question 12

What cancers are most associated with a lack of physical activity?

Answer 12

• Bowel, breast (post-menopausal) and endometrial - independent of body weight and other confounding factors

Question 13

What has been found on prevalence of cancer and physical activity?

Answer 13

• Inactivity found for 13-14% of bowel cancer incidence and 11% of breast cancer
• 22% of endometrial cancer diagnoses could be avoided if all women exercised three hours at a moderate intensity
• Walking/cycling for one hour = 16% less likely to develop cancer and 34% less likely to die from cancer

Question 14

What effect does physical activity have on the risk of bowel cancer?

Answer 14

• Reduce risk of bowel cancer 25%
  1) Leads to regular bowel movements - carcinogenic substances pass easily
  2) Reduces levels of insulin, hormones and other growth factors
  3) Reduces inflammation in the bowel itself

Question 15

What effect does physical activity have on breast cancer?

Answer 15

• Reduces breast cancer risk 20-40% - every additional hour activity reduces breast cancer risk 6%
• EPIC study showed NEAT is of benefit
• Physical activity lowers levels of insulin, hormones and other growth factors as well as may alter oestrogen metabolism

Question 16

What is the evidence of physical activity on endometrial cancer?

Answer 16

• 5 prospective studies showed physical activity was associated with a 30% lower risk

Question 17

What are the types of skin cancer?

Answer 17

• Non-melanoma skin cancer (NMSC) and malignant melonama skin cancer - MMSC is more serious

Question 18

What are the non-modifiable risk factors for cancer?

Answer 18

1) Ionising radition
2) Certain chemical viruses and bacteria
3) Socioeconomic class
4) Family history of cancer
5) Ageing

Question 19

How does ionising radiation act as a risk factor?

Answer 19

• Can cause harmful genetic mutations that can be passed on to future generations
• X-ray exposure in hospitals
• Alpha, beta particles and gamma rays can come from natural sources or can be technologically produced
• Natural radiation from cosmic rays, naturally occuring radioactive elements in Earth’s crust (uranium, thorium etc), and radioactive decay products such as radon and its subsequent decay products
• Damage may not show for months or years - leukaemia has a minimum time period of 2 years

Question 20

Name 3 chemicals which are related to cancer

Answer 20

1) aflatoxins - naturally occuring toxins produced by certain moulds growing on some food crops during production and storage
2) asbetos - microscopic fibres can be inhaled and stay dormant in lung for years
3) benzene - used to be found in petrol is still used in controlled situations in certain industries

Question 21

How does cancer prevalence differ with socioeconomic status?

Answer 21

• Cervical and lung are more common in people of lower socioeconomic stats
• Breast cancer and melanoma are more frequent in individuals living in areas of higher socioeconomic status

Question 22

What ways are there to tell if cancer might run in the family?

Answer 22

• Several cancers of same type
• Several cases of rare cancer
• Family members developed cancer before age 50
• Family members developed more than 1 tumour

Question 23

What are the genes accounting for breast cancer and how many cases are attributable to these genes?

Answer 23

• BRCA1 and BRCA2 - less than 5% of cases can be attributed to these genes

Question 24

Why does ageing increase the risk of cancer?

Answer 24

• Aged mother cells show increase in genomic instability and a greater chance of cancer cells being produced

Question 25

What 11 recommendations are given in the European Union consensus paper to reduced risk of getting cancer?

Answer 25

1) Do not smoke
2) Avoid obesity,
3) Undertake some moderate intensity physical activity everyday
4) Increased daily intake of a variety of ruits and vegetables - eat 5 servings daily - Limit intake from fats and animal sources
5) Two drinks a day if a man and one drink a day women max
6) Avoid excess sun exposure
7) Regulations agaisnt cancer causing substances - masks etc
8) Women from age 25 should participate in cervical screening programmes
9) Women aged 50 should participate in breast screening
10) Men and Women age 50 should participate in colorectal screnning
11) Participate in vaccination programmes agaisnt hepatitis B virus programmes

Question 26

What are the 5 cancers estimated to be preventable in the UK through healthy changes

Answer 26

1) Oesophagues
2) Mouth, pharynx and larynx
3) Endometrial
4) Stomach
5) Bowel `