Genetic Mutations:
* Proto-oncogenes: These genes normally promote cell growth and division. Mutations can turn them into oncogenes, constantly driving cell proliferation.
* Tumor suppressor genes: These genes normally act as "brakes" on cell growth. Mutations inactivate these genes, removing the brakes and allowing uncontrolled growth.
* DNA repair genes: These genes fix errors in DNA, preventing mutations. Mutations in these genes increase the risk of other mutations, including those in proto-oncogenes and tumor suppressor genes.
Environmental Factors:
* Carcinogens: These substances can directly damage DNA, leading to mutations. Examples include tobacco smoke, UV radiation, and certain chemicals.
* Infections: Some viruses, like HPV and hepatitis B, can integrate their DNA into the host's genome, disrupting gene function and increasing cancer risk.
* Lifestyle choices: Diet, exercise, alcohol consumption, and other lifestyle factors can influence cancer risk by affecting DNA damage and repair mechanisms.
Other factors:
* Hormones: Some hormones can stimulate cell growth and may play a role in certain cancers.
* Immune system dysfunction: A weakened immune system may be less effective at eliminating cancer cells.
* Age: The risk of cancer increases with age, as cells accumulate more mutations over time.
It's important to note that cancer is a complex disease, and the specific causes vary depending on the type of cancer. While the factors mentioned above are major contributors, the precise mechanisms by which they lead to uncontrolled cell growth are still being researched.
