Brief 2: Cancer Knowledge: Understanding cancer risk and reducing cancer risk

64% of Americans Believe Some Cancers Are Preventable

Moving from awareness to behavior remains a challenge

More than 64% of Americans believe that lifestyle and behavior influence cancer risk. They’re right! It is estimated that 50% to 75% of cancer deaths each year are caused by behaviors such as smoking, physical inactivity, and poor dietary choices.

When asked what people can do to lower their chances of getting cancer, the majority of respondents to the Health Information National Trends Survey (HINTS 2003) accurately reported that never smoking or quitting smoking reduces cancer risk. Indeed, lung cancer is the leading cause of cancer death among men and women, and tobacco use is the single most preventable cause of cancer death in the United States.

Many Americans recognize that eating well can reduce their risk for cancer: 25% of Americans report that eating a better diet can reduce a person’s risk of getting cancer. In fact, diets high in fat and low in fruits and vegetables are linked with several types of cancer.

The charts on this page summarize population estimates of people’s perceptions of the role of lifestyle in cancer, and behaviors they believe can reduce cancer risk. Interestingly, while most Americans know the dangers of smoking and its link to lung cancer, 48% inaccurately believe that breast and prostate cancers exact a greater annual death toll than lung cancer. Furthermore, 54% of Americans report that there is nothing they would like to change to reduce their own risk.

Although the American public demonstrates awareness of key cancer prevention activities, 15% of Americans, more than 32 million, believe that nothing can reduce a person’s cancer risk. Furthermore, 1% of Americans, over 3 million, are not able to pinpoint a specific action that they could take to reduce their own risk of getting cancer.

Do you agree or disagree that there’s not much people can do to lower their chances of getting cancer?

d

What can people do to reduce their chances of getting cancer?

d

What Do Smokers Believe about Their Risk for Lung Cancer?

In a study using HINTS 2003 data, investigators found that current smokers significantly underestimate their risk for developing lung cancer and other tobacco-related illnesses. Smokers think that their own risk for lung cancer is lower than the risk of the average smoker. In addition, the study showed that smokers underestimate the extent to which smoking elevates their lung cancer risk above that of nonsmokers: more than half of current smokers regarded their lung cancer risk as no more than twice that of non-smokers; in fact, even for light smokers in the sample, their risk would be about nine times the non-smoker’s risk.

Although 13% of the respondents to HINTS 2003 said that quitting smoking was a behavior they’d like to change to reduce their cancer risk, many smokers and former smokers endorse several myths about cancer risk reduction. More than half mistakenly think that exercise can "undo" most of the negative health consequences of smoking, and almost one third believe that vitamins are beneficial in reversing the effects of tobacco use.

Desired Behavior Change: Differences by Age, Race, and Gender

HINTS 2003 reveals that most people believe cancer is preventable, and that many people can identify health behaviors that reduce cancer risk. While the majority of respondents to HINTS admitted that there are no lifestyle changes they would like to make to reduce their own risk for cancer, those who expressed a desire to change are quick to identify relevant behaviors. When asked if there was anything about their behavior or lifestyle that they would like to change to reduce their own cancer risk, respondents most frequently identified smoking cessation or avoidance, improving nutrition, and practicing a healthy lifestyle that includes exercise and weight loss. Here we explore how those responses differ by age, race, and gender.

Age

• Of those respondents who said that they’d like to change their diets to reduce their own risk for cancer, nutrition was mentioned more frequently by those aged 35-64 (34.1%) compared with those 18-34 (26.2%) and those 65 and older (29.5%).
• A higher percentage of respondents aged 18-34 (43.5%) said they’d like to quit or avoid smoking to reduce their cancer risk compared with respondents aged 35-64 (30.3%) and those 65 and older (20.6%).
• Respondents aged 65 or older (42.0%) more frequently identified practicing a healthy lifestyle that includes exercise and weight loss as a desired behavioral change compared with those 18-34 (16.6%) and 35-64 (26.9%).

Race/Ethnicity

• A higher percentage of non-Hispanic blacks (41.5%) identified smoking cessation or avoidance as a change they’d like to make to reduce their cancer risk compared with Hispanics (28.6%), non-Hispanic whites (32.3%), and non-Hispanic others (35.2%).
• A higher percentage of non-Hispanic whites (26.0%) compared with Hispanics (23.5%), non-Hispanic blacks (22.6%), and non-Hispanic others (23.1%) said that they’d like to exercise and lose weight to reduce their cancer risk.

Gender

• A higher percentage of females (33.1%) than males (29.1%) said they’d like to eat a better diet to help prevent cancer.
• A higher percentage of males (40.3%) than females (27.5%) identified smoking cessation or avoidance as a needed change to reduce their cancer risk.
• A healthy lifestyle including exercise and weight loss was identified as a desired change by a higher percentage of females (30.3%) compared with males (19.3%).

References Used in This HINTS Brief

NCI’s Cancer Trends Progress Report 2005, http://progressreport.cancer.gov

Weinstein ND, Marcus SE, Moser RP. Smokers' unrealistic optimism about their risk. Tob Control. 2005 Feb;14(1):55-9.

For More Information on Cancer

• Call the NCI Cancer Information Service at 1-800-4-CANCER (1-800-422-6237)



• Visit http://cancer.gov



• Order NCI publications at http://www.cancer.gov/publications

March 2006