Why does starting to smoke at a young age increase lung cancer risk?

Starting to smoke at a young age significantly increases the risk of developing lung cancer primarily because the risk of the disease is strongly related to both the amount and the duration of exposure to tobacco toxins.1

Cigarette smoke contains more than 60 known carcinogens, which can bind to and damage cellular DNA. When cells with damaged DNA survive and replicate, cancers can develop. Because the likelihood of developing a tobacco-related cancer increases the longer and more frequently a person smokes, individuals who begin at a young age experience a longer duration of exposure over their lifetime. This persistent exposure to cancer-causing agents, often compounded by addiction, creates a higher cumulative risk for the disease compared to those who start later in life or smoke for shorter periods.12