Prevention

Cancer prevention is defined as active measures to decrease the risk of cancer.^[39] The vast majority of cancer risk factors are due to environmental (including lifestyle) factors, and many of these factors are controllable. Thus, cancer is largely considered a preventable disease.^[40] Greater than 30% of cancer is considered preventable by avoiding risk factors including: tobacco, overweight / obesity, an insufficient diet,physical inactivity, alcohol, sexually transmitted infections, and air pollution.^[41] Not all environmental causes can be prevented. For example, exposure to naturally occurring background radiation cannot be prevented.