Previous studies have shown that several modifiable risk factors may increase a person’s risk of cancer. A new study from the American Cancer Society found that four in 10 cancer diagnoses and nearly half of cancer deaths in U.S. adults age 30 and older can be attributed to modifiable risk factors. Scientists report that smoking is the leading risk factor for nearly 20 percent of all cancer cases and 30 percent of all cancer deaths.
Previous studies have shown that there are several modifiable risk factors that can increase a person’s risk of cancer, including smoking, alcohol consumption, obesity, and a sedentary lifestyle.
Now, a new study by the American Cancer Society (published in CA: A Cancer Journal for Clinicians) reports that four out of every 10 cancer diagnoses and nearly half of cancer deaths in U.S. adults age 30 and older may be due to these types of reversible risk factors.
For the study, the researchers used 2019 information from a variety of nationally representative data on cancer incidence and mortality, and the prevalence of risk factors.
Risk factors the scientists investigated included:
“Information on the proportion and number of cancer cases and deaths attributable to potentially modifiable risk factors can help us better prioritize cancer prevention and control efforts,” Farhad Islami, MD, senior scientific director for Cancer Disparities Research at the American Cancer Society and lead author of the study, told Medical News Today.
“Furthermore, it can increase public awareness about cancer risk factors, which may lead to reducing exposure to these risk factors, such as quitting smoking, maintaining a healthy weight and diet, and getting the HPV vaccination,” he noted.
In their analysis, the researchers found that smoking was responsible for the largest proportion of cancer cases, about 20 percent.
Smoking correlated with 56% of all preventable cancers in men and about 40% of preventable cancer cases in women.
Furthermore, scientists have concluded that smoking is responsible for 30% of all cancer deaths.
“We already know that smoking is the most common modifiable cancer risk factor in the United States,” Islami said. “Although great progress has been made in reducing smoking prevalence over the past few decades, we need to continue and intensify our efforts to further reduce smoking.”
“It is also important to note that not all states and socioeconomic groups have benefited equally from this progress,” he added. “Our findings underscore the importance of states implementing comprehensive tobacco control policies, including broad and equitable implementation of interventions to promote smoking cessation among all socioeconomic groups.”
After smoking, the four main modifiable risk factors for all cancer cases are:
Excess weight, alcohol consumption, exposure to UV rays, and lack of physical activity.
“Many cancer cases and deaths in the United States are attributable to these potentially modifiable risk factors, suggesting that widespread and equitable implementation of preventive measures could significantly reduce the burden of cancer,” Islami said. “Several measures are recommended to reduce exposure to these risk factors.”
He elaborated:
“With regard to UV rays, these include limiting excessive sun exposure (e.g., avoiding direct sunlight between 10 a.m. and 4 p.m. and seeking shade), wearing protective clothing, hats, and sunglasses, and regularly applying broad-spectrum UVA and UVB blocking sunscreen. Some of these measures, such as providing adequate shade in parks, children’s playgrounds, and other areas, will require multicomponent interventions at the community level.”
“There is also a need for more implementation research to broadly adapt known interventions, particularly those for overweight, unhealthy diet, alcohol use, and physical inactivity, to identify tailored, mutually reinforcing interventions that are more likely to reduce these risk factors, particularly those that typically affect historically marginalized populations disproportionately,” Islami added.
Islami and his team also looked at the impact of modifiable risk factors on 30 specific cancer types.
During the study, the researchers found that more than 50 percent of cases of 19 of the 30 cancer types evaluated could be attributed to potentially modifiable risk factors.
Among the cancers most highly likely to be caused by these presumably reversible risk factors are 100% of cervical cancer and Kaposi’s sarcoma, 94.2% of anal cancer, 92.2% of more than 80% of cutaneous melanoma, and 88.2% of lung cancer.
“For some risk factors, exposure to some organs is more common or intense, for example tobacco smoke in the lungs, and this may play a role in the stronger association between smoking and lung cancer,” Islami explained.
He also highlighted the role that certain viruses, such as HPV, which can be prevented by vaccination and cervical cancer screening, play in cancer risk.
“Some risk factors may pose a greater risk in certain cells or tissues. For example, human papillomavirus is more likely to cause cancer in squamous epithelial cells, but it can also cause cancer in glandular cells. The biological reasons for these differences require further study,” he further pointed out.
After reviewing the study, Nilesh Vora, MD, medical director and hematologist and oncologist at MemorialCare Todd Cancer Institute at Long Beach Medical Center in Long Beach, California, who was not involved in the study, told MNT that the results were not surprising.
“We talk about modifiable risk factors all the time. We see patients with newly diagnosed cancer all the time, and often we find the same types of risk factors that were found in this study,” Vora said.
“This type of information is a really good way to educate primary care providers, who are on the front lines of prevention, so by incorporating all the interventions we can do to modify these risk factors, we can reduce the chances that patients will develop cancer,” he added.
“We would love to see this type of data shared with our community — not just with health care providers, but also with patients, either directly or through the health care providers who see patients on a regular basis, to really educate people about how these risk factors lead to cancer,” Vora emphasized.
