The role Obesity and Physical activity Increases Cancer Risk Flashcards
What are High risk cancers associated with obesity?
- Endometrial (lining of the uterus)
- Esophageal (due to acid reflux)
What is endometrial cancer strong relationship between obesity?
Strongest relationship with increasing BMI. Each 5kg/m2 increase of BMI increases cancer risk of 60%
What is endometrial cancer independent to?
Independent of menopausal status
Why is esophageal cancer increasing in North America at a high rate?
More number of obese people who experience higher rate of acid reflux
What relationship does esophageal cancer have with obesity and mortality?
Does-effect relationship. The more people who are obese, more likely to die from cancer
How does obesity relate to breast cancer?
- Obesity is a major risk factor for postmenopausal breast cancer
- Higher risk of reoccurrence
- Poorer overall survival (55% 5-year survival if obese vs 80% if lean)
What is protective when of the breast cancer risk when obese?
Obese Women when they are Premenopausal
What increases risk of breast cancer in obese women?
Obese women who are postmenopausal
What is Colorectal linked to?
Early stage tumourigenesis, may or may not turn into cancer
How is obesity related to colorectal cancer?
May be interaction with physical activity, people with highest BMIs and lowest PA are at the greatest risk of colorectal cancer
What other factors independently increase risk of Renal-Cell cancer?
Diabetes and Hypertension
What type of relationship does renal-cell cancer have with mortality?
Dose-effect - the bigger the BMI the more likely to die from renal-cell cancer
What is the research and info behind prostate cancer and obesity?
Currently limited information/research.
- Obesity protective for low grade PC and increased risk for high grade PC
What are pathophysiological mechanisms related to obesity and cancer risk?
Best understood in endocrine cancers
- Hyperinsulinemia/IGF-1
- Endogenous sex steroids
- Inflammation and oxidative stress
What is Hyperinsulinemia/Insulin-like Growth Factor-1?
Linked to insulin resistance, present when Muscle/liver tissues have a reduced response to insulin and Overcompensation of the pancreatic insulin occurs
What cancers is chronic hyperinsulinemia & IGF-1 linked to?
- Colon
- Endometrium
- Pancreas
- Breast
What does Hyperinsulinemia and IGF-1 promote?
Tumour development and inhibit apoptosis
What do Endogenous Sex Steroids do?
- Stimulate cell proliferation
- Inhibit apoptosis
- Increase risk of tumour development
How is TGF-1 and Insulin related to sex steroids?
- They stimulate synthesis of sex steroids
- Inhibit synthesis of sex hormone-binding globulin (gets “rid of” sex steroids)
What sex steroid does body fat primarily produce?
Body fat is a primary producer of estrogen (a sex steroid) in postmenopausal women
How does obesity increase endogenous sex steroids?
- Increased production of androgens, causing less ovulation, lower progesterone
- This increases risk of endometrial cancer
Is obesity related to inflammation?
Yes, associated with chronic inflammation
What causes inflammation?
High production of certain cytokines
Why can inflammation increase risk of cancer?
Overproduction of cytokines can increase tumour initiation, growth and progression
When is physical activity associated with cancer risk?
- Caloric Intake
- Free Radicals
- Trauma
- Pulmonary Function
- Immune Function
How is Caloric Intake a risk factor due to physical activity and enhancing cancer?
Very Active people eat more food where they can be exposed to more carcinogens and toxins. Not normally an issue for moderately active people
Is food restriction harmful for increasing risk of cancer?
No, food restriction reduces risk of cancer due to the physiologic state of body shifting from cellular proliferation to maintenance
How is High Protein intake a risk factor due to physical activity enhancing cancer?
Competitors in some sports consume a high quantity of animal protein, this is associated with increase cancer risk
Are vegetarians less likely to develop cancer?
60% less risk of cancer compared to meat eaters
What do Free Radicals do?
They cause cellular damage
Why are free radicals related to physical activity and cancer risk?
Vigorous physical activity associated with increased free radicals causing excess damage to cells
How can trauma due to physical activity increase cancer risk?
Vigorous physical activity can:
- Increase risk of injury
- Cause more cell division
All increases risk of cancer
Is trauma and physical activity increasing cancer risk conclusive?
No, not enough research. Trauma can increase some kinds of cancer
Example of Physical activity trauma increasing cancer risk?
Sitting on a bike for long periods of time cause trauma to the testicular region increasing risk of testicular/prostate cancer
Is trauma a problem for cancer risk in moderately active people?
No. More harmful for vigorous exercisers
How is pulmonary function increase cancer risk during physical activity?
Competitors in some endurance sports have larger lung space, increasing cancer risk:
- More epithelial cells, more space for tumour growth
- Altered pattern of air flow (particles get into lungs easier)
Is pulmonary function harmful for moderate exercisers?
No
Is physical activity harmful to the immune function?
Yes
What can happen to extreme exercisers immune function?
Can develop the same kind of immunedepression as patients with HIV infection
Who develops immunedepression?
Vigorous exercisers who participate in high levels of physical activity
Not harmful for moderate exercisers
