Cancer Causes and Risk Factors

Study Notes

Cancer arises from mutations tipping the balance towards uncontrolled cell growth.
Proto-oncogenes promote cell growth, while tumor suppressor genes inhibit it.
Age is the strongest risk factor for cancer.
Cancer incidence rates increase significantly with age.
Modifiable lifestyle choices, like diet and activity, significantly influence cancer risk.
Unhealthy diets, lack of physical activity, and unhealthy habits (like smoking and alcohol consumption) increase cancer risk.
Alcohol consumption is linked to several cancer types, causing significant liver damage.
Alcohol is estimated to cause 4% of cancers in the UK, with approximately 12,800 cases annually.
Alcohol damages the liver, especially leading to inflammation.
The process of alcohol metabolism forms acetaldehyde, damaging the liver, and increasing cancer risk.

DNA damage from various sources initiates cancer.
Factors like exposure to radiation, chemicals (like benzo(a)pyrene), and reactive oxygen/nitrogen species contribute to DNA damage.

Various DNA repair mechanisms exist to correct damage, but their insufficiency can lead to cancer.
These mechanisms include base excision repair, nucleotide excision repair, mismatch repair, homologous recombination, and non-homologous end joining.
Damage and failures in these pathways contribute to cancer development.

Diet plays a crucial role in cancer risk.
A diet rich in fiber may reduce bowel cancer risk.
Fruits and vegetables are associated with a lower risk of mouth, throat, and lung cancer.
Processed and red meat have been linked to increased bowel cancer risk.

Infections are responsible for 16% of cancers globally.
Examples of infections include H. Pylori, HPV, HCV, HBV, EBV, and those leading to Kaposi's sarcoma.

Some genetic mutations inherited from parents significantly influence cancer risk.
Genes like BRCA1/2, MLH1, MSH2, MSH6, PMS2, TP53, PTEN, and VHL are pivotal in cancer development.
These genes often influence DNA repair mechanisms or cellular processes crucial for preventing abnormal growth.

Environmental factors like UV radiation, occupational chemicals, and natural products contribute to DNA damage.
These environmental factors influence the risks of various cancers.