Modifiable Risk Factors of Cancer

An up-to-date analysis of the number of cancer cases and deaths in the U.S. preventable by modifiable factors was recently published in CA: A Cancer Journal for Clinicians. This analysis was based on data from 2019, estimating the number of cancers (including 30 specific types of cancer, but excluding nonmelanoma skin cancer) that could be prevented using well-established relative risks derived largely from meta-analyses for modifiable factors with strong/sufficient evidence establishing risk. For example, this includes factors such as smoking, excess body weight, physical inactivity, etc. For each cancer the “population attributable fraction” or PAF was calculated, representing the proportion of a specific cancer attributable to a specific risk factor.

Overall, this estimate found that 40% of all incident cancers among adults age 30+ living in the U.S. could have been prevented, as well as 44% of cancer deaths. Cigarette smoking remains the largest single cause of cancer incidence and death, and is responsible for 19.3% of cases and 28.5% of cancer deaths. Excess body weight, only somewhat recently recognized as a risk factor for cancer, was responsible for the 2nd largest cause of cancer incidence and death, with a PAF of 7.6% and 7.3% of cases and deaths, respectively.  

Some of the other top causes of cancer death included alcohol consumption, low fruit/vegetable intake, physical inactivity, UV radiation, processed and red meat consumption, and several infections (e.g., H. pylori, HIV, HPV, EBV, etc.). This report also details which cancers are the most affected by the above factors; for example, 100% of cervical cancer cases could be attributed to these factors, yet on the other end of the spectrum, only 4.9% of ovarian cancer cases could be explained by these factors. Additionally, the effect of some risk factors could be taken into consideration together; for example, excess body weight, alcohol, dietary factors, and physical inactivity, together, were the single largest cause of cancer in women, and the 2nd in men (after tobacco).