initiator

Carcinogenesis is the production of cancer, a disease characterized by uncontrolled cell growth and the potential to invade other tissues. This process can be initiated by various agents, broadly categorized as chemical, physical, or viral carcinogens.12

Chemical carcinogens, such as those found in tobacco smoke or industrial pollutants, often interact with a cell's DNA, causing mutations that disrupt normal cellular function. This initial DNA damage is called initiation. For a tumor to develop, initiation must be followed by promotion, where chemicals stimulate the proliferation of these damaged cells. Promoters do not cause DNA damage themselves but encourage the growth of initiated cells, leading to tumor formation. Some chemicals, known as complete carcinogens, can both initiate and promote tumors.3245

Physical carcinogens include radiation like sunlight and X-rays, while oncogenic viruses can also cause cancer. Internal factors like genetic predispositions and hormonal imbalances can also play a role in cancer development.23