This article is more than 5 years old. Information may no longer be current.
Many cancers associated with modifiable risk factors
Click Here to Manage Email Alerts
Cigarette smoking, excess body weight and alcohol intake represented the three most prevalent modifiable risk factors for cancer, according to an American Cancer Society study published in CA: A Cancer Journal for Clinicians.
An estimated 42% of all incident cancers among adults aged 30 years and older could be attributed to potentially modifiable risk factors, researchers reported.
“About one-half of all cancer deaths in the United States are attributable to potentially modifiable risk factors,” Farhad Islami, MD, PhD, strategic director of cancer surveillance research at the American Cancer Society, told HemOnc Today. “Our results have important implications at multiple levels. Individuals should avoid or reduce exposure to these risk factors. There is also a continued need to increase equitable access to preventive health care and awareness about preventive measures.”
The cancer mortality rate in the United States has decreased by 25% since 1991. However, more than 1.6 million new cancer diagnoses and 600,000 cancer deaths are estimated to occur in 2017. Direct medical costs for cancer are estimated to total $88 billion to $124 billion per year.
Leading cancer risk factors
Islami and colleagues estimated the proportion and number of invasive cancer cases and deaths overall attributable to potentially modifiable exposures for 26 cancer types — excluding nonmelanoma skin cancers — among adults aged 30 years and older in 2014.
Risk factors included cigarette smoking; secondhand smoke; excess body weight; alcohol intake; consumption of red and processed meat; low consumption of fruits and vegetables, dietary fiber and dietary calcium; physical inactivity; UV radiation and six cancer-associated infections.
Researchers obtained data on cancer cases from the CDC and NCI; the numbers of deaths from the CDC; risk factor prevalence estimates from nationally representative surveys; and associated relative risks for cancer from published, large-scale pooled analyses or meta-analyses.
According to Islami and colleagues, 659,640 of more than 1.5 million cancers diagnosed (42%) and 265,150 of 587,521 cancer deaths (45.1%) in 2014 were attributable to modifiable risks.
Cigarette smoking accounted for highest proportion of cancer cases (19%) and deaths (28.8%). In fact, cigarette smoking accounted for 55.5% of all potentially preventable cancers among men (184,400 of 332,320 cancers) and 35% among women (114,520 of 327,240 cancers). Smoking accounted for 81.7% of lung cancers, 73.8% of larynx cancers, 50% of esophageal cancers and 46.9% of bladder cancers.
“Our results show that smoking is associated with far higher cancer burden than any other single risk factor in the United States,” Islami said, adding that the growing prevalence of excess body weight, excessive alcohol drinking, unhealthy diet and physical inactivity are expected to further increase in the future.
“This does not mean that other risk factors evaluated in this study are not important,” he said. “For example, UV light from sun exposure and indoor tanning causes about 75,000 skin melanomas every year in the United States, plus a far higher number of nonmelanoma skin cancers — 4.3 million with these cancers are treated annually in the United States. It is important to prevent any cancer that is potentially preventable.”
Excess weight accounted for the second-highest proportion of cancer cases (7.8%) and deaths (6.5%), followed by alcohol intake (5.6% cases; 4% deaths), UV radiation (4.7%; 1.5%) and physical activity (2.9%; 2.2%). Low fruit and vegetable intake accounted for 1.9% of cancer cases and 2.7% of deaths, and HPV infection accounted for 1.8% of cases and 1.1% of deaths.
Nearly 86% of lung cancer cases (184,970 cases; 132,960 deaths) were attributable to evaluable risk factors, followed by 71% of liver cancers, 54.6% of colorectal cancers and 28.7% of breast cancers.
Other findings in the report included:
- Excess body weight was associated with 60.3% of uterine cancers, 33.9% of liver cancers, 11.3% of breast cancers in women and 5.2% of colorectal cancers. Excess body weight accounted for 7.8% of evaluable cancer cases and caused twice as many cancers among women than men (10.9% vs. 4.8%);
- Alcohol intake was associated with 46.3% of oral cavity and pharyngeal cancers among men and 27.4% among women; 24.8% of liver cancers among men and 11.9% among women; 17.1% of colorectal cancers among men and 8.1% among women; and 16.4% of breast cancers among women;
- UV radiation was associated with 96% of skin melanomas among men and 93.7% among women;
- Physical inactivity accounted for 26.7% of uterine cancers, 16.3% of colorectal cancers and 3.9% of female breast cancers;
- Low fruit and vegetable consumption was associated with 17.6% of oral cavity/pharyngeal cancers, 17.4% of laryngeal cancers and 8.9% of lung cancers; and
- Red meat consumption accounted for 5.4% of colorectal cancers, and processed meat consumption accounted for 8.2% of colorectal cancers. Low dietary fiber accounted for 10.3% of colorectal cancer cases, and low dietary calcium accounted for 4.9% of cases.
When measuring excess body weight, alcohol intake, poor diet and physical inactivity together, the risk factors for cancer were 13.9% among men and 22.4% among women. Risk for cancer death in those meeting that combined criteria was 14.9% among men and 16.9% among women.
Reducing risk
Modifying behaviors is rarely easy, Islami said.
“This is made more challenging by the marketing strategies of industries that benefit from elevated exposure to these risk factors, notably the tobacco industry,” he said. “However, the good news is that there are many known effective preventive strategies to reduce exposure to these risk factors.”
Multicomponent interventions may be the most efficient strategies to reduce the burden of cancer in the United States, Islami said.
“For example, persons who currently smoke can reduce their health risks by quitting,” he said. “Health care providers can also provide guidance for quitting.”
Researchers noted that state-level tax per cigarette pack as of April 2017 ranged from 17 cents in Missouri to $4.35 in New York.
“Tobacco control policies, including tobacco taxation, smoke-free laws, assistance with smoking cessation, warning labels, media campaigns and marketing bans can increase the number of smokers who quit smoking and reduce the number of nonsmokers who initiate smoking,” Islami said.
Political commitment at the local, state and federal levels is needed to implement or enforce effective preventive strategies, Islami added.
“For some potentially modifiable risk factors, including unhealthy diet and physical inactivity, more research is still needed to identify tailored, more efficient interventions, as well as further implementation research for widespread application of known interventions,” he said. – by Chuck Gormley
For more information:
Farhad Islami, MD, PhD, can be reached at farhad.islami@cancer.org.
Disclosures: The authors report no relevant financial disclosures.
Click Here to Manage Email Alerts