Final answer:
Smoking is the number-one preventable cause of cancer, accounting for approximately 25% of cancer deaths. Other significant but preventable risk factors include exposure to UV light, unhealthy diets, and physical inactivity, all of which are important to address for cancer prevention.
Step-by-step explanation:
The number-one preventable cause of cancer is smoking. It is estimated that not using tobacco would prevent around 25 percent of cancer deaths. While there are many environmental risk factors for cancer, including UV light exposure and pollution, smoking remains the predominant cause of preventable cancer. Avoidable lifestyle choices such as smoking tobacco, consuming an unhealthy diet, and not engaging in physical activity contribute significantly to the incidence of cancer.
While UV radiation from the sun is a major cause of skin cancer, it does not surpass tobacco in terms of the overall number of cancers caused. Considering that about 22% of cancer-related deaths are due to smoking and exposure to carcinogens found in tobacco smoke, it is clear that smoking is the leading preventable risk factor. Furthermore, sedentary lifestyles and poor diets contribute to at least a third of cancer deaths, highlighting the importance of healthy living in cancer prevention.