For this study, researchers used 2019 information from various nationally representative data on cancer incidence and mortality, as well as risk factor prevalence.
Risk factors that the scientists examined included:
“Information on the proportion and number of cancer cases and deaths attributable to potentially modifiable risk factors is useful for setting more pertinent priorities for cancer prevention and control initiatives,”
“Additionally, it can increase the awareness of the public about risk factors of cancer, which might result in a reduction in exposure to these risk factors, such as smoking cessation, maintaining healthy body weight and diet, HPV vaccination, and so on,” he noted.
Upon analysis, researchers found that cigarette smoking was attributable to the largest percentage of cancer cases, at almost 20%.
Smoking was correlated to 56% of all potentially preventable cancers in men and about 40% of preventable cancer cases in women.
Additionally, the scientists linked cigarette smoking to 30% of all cancer deaths.
“We already knew that smoking is the most common modifiable risk factor for cancer in the United States,” Islami said. “We have seen substantial progress in reducing smoking rates in the past few decades, but we need to continue and enhance our efforts to further reduce smoking.”
“It should also be noted that not all states and socioeconomic groups have equally benefited from this progress,” he added. “Our findings underscore the importance of implementing comprehensive tobacco control policies in each state, including broad and equitable implementation of interventions to promote smoking cessation among all socioeconomic groups.”
After cigarette smoking, the four other leading modifiable risk factors for all cancer cases were:
- excess body weight
- alcohol consumption
- UV radiation exposure
- physical inactivity.
“A large number of cancer cases and deaths in the United States are attributable to these potentially modifiable risk factors, indicating the potential to substantially reduce the cancer burden through broad and equitable implementation of preventive initiatives,” Islami said. “Several measures have been recommended to reduce exposure to these risk factors.”
“For UV radiation, these measures include limiting excessive sun exposure — e.g., avoiding direct sun exposure between 10 a.m. and 4 p.m., seeking shade — [as well as] wearing protective clothing, hats, and sunglasses, and regular application of broad‐spectrum UVA and UVB-blocking sunscreens. Some of [these] measures, such as providing sufficient shading in parks, children’s playgrounds, and other places, will require multicomponent interventions at the community level.”
“We also need more implementation research for broad application of known interventions, especially for excess body weight, unhealthy diet, alcohol consumption, and physical inactivity, and to identify tailored and mutually reinforcing interventions, as they are more likely to mitigate these risk factors, especially in historically marginalized populations, which are usually disproportionately affected by these factors,” Islami added.
Islami and his team also looked at the impact of modifiable risk factors on 30 specific cancers.
During the study, researchers found that more than 50% of cases of 19 of the 30 types of cancer evaluated could be attributed to potentially modifiable risk factors.
“For some risk factors, the exposure is generally more common or intense in some organs, for example, tobacco smoke in [the] lung, and this may play a role in a stronger association between smoking and lung cancer,” Islami explained.
He also emphasized the role that certain viruses, such as HPV — which people can prevent through vaccination and cervical screening — play in cancer risk.
“Some risk factors may be associated with a greater risk in certain cells or tissues; for example, human papillomavirus is more likely to cause cancer in squamous cells — although it can cause cancer in glandular cells, too. The biological reasons for these differences need further research,” he further noted.
After reviewing this study, Nilesh Vora, MD, a board-certified hematologist, medical oncologist, and medical director of the MemorialCare Todd Cancer Institute at Long Beach Medical Center in Long Beach, CA, who was not involved in this research, told MNT that the results were not surprising.
“We talk about modifiable risk factors all the time. We see patients all the time who have new diagnoses of cancer and oftentimes, we find the same type of risk factors that this study found,“ said Vora.
“This kind of information is a really good way to educate our primary care providers who are at the forefront of prevention. And so incorporating all of the interventions we can to modify these risk factors can reduce the chance of a patient acquiring cancer,” he added.
“I’d like to see this type of data be shared with our community — not only our providers, but also our patients, either directly or via the providers who are seeing them on a regular basis, really teaching people about how these risk factors can lead to cancer,” Vora emphasized.