The incidence of cancer increases dramatically in older humans because?
As individuals age, several factors contribute to the increased incidence of cancer:
Cellular senescence: As cells undergo repeated rounds of cell division, they eventually reach a state of cellular senescence, where they lose their ability to divide and function properly. This accumulation of senescent cells can lead to the development of cancer.
DNA damage: Throughout a person's lifetime, DNA is constantly exposed to various damaging agents, such as ultraviolet (UV) radiation from the sun, environmental toxins, and free radicals produced during cellular metabolism. DNA damage can lead to mutations that can drive cancer development.
Immune system decline: The immune system plays a crucial role in detecting and eliminating abnormal or damaged cells, including those with the potential to become cancerous. However, as people age, their immune system's efficiency declines, making them more susceptible to the development and growth of cancer cells.
Chronic inflammation: Chronic inflammation is associated with increased cancer risk. As we age, the body experiences various inflammatory processes, and prolonged or chronic inflammation can damage cells and contribute to the development of certain types of cancer.
Altered gene expression: Over time, changes in gene expression patterns can occur, potentially leading to the activation of oncogenes (genes that promote cell growth and division) and inactivation of tumor suppressor genes (genes that control cell growth and division). These genetic changes are involved in cancer initiation and progression.
Lifestyle and environmental factors: Certain lifestyle choices and environmental factors accumulate over time and can contribute to cancer development. Factors such as tobacco smoking, excessive alcohol consumption, unhealthy diet, lack of physical activity, and exposure to certain chemicals and pollutants can increase the risk of various types of cancer.
The combination of these age-related changes, including cellular senescence, DNA damage, immune system decline, chronic inflammation, altered gene expression, and cumulative environmental factors, contributes to the increased incidence of cancer in older individuals.