What Americans Don’t Know About Cancer

large man measuring his waist with a tape measure

A national household survey sponsored by the American Society of Clinical Oncology (ASCO) shows most Americans have concerns about cancer, but have gaps in their knowledge about what causes it. About 4,000 adults completed the survey, conducted by Harris Poll, in July. Questions focused on knowledge and attitudes about cancer.

Results were similar to those of previous survey findings from the American Institute for Cancer Research (AICR). Both surveys show most Americans are unaware that lifestyle factors including body weight, diet, physical activity, and alcohol consumption raise cancer risk. The World Cancer Research Fund estimates that 20% of all cancers diagnosed in the US are related to these lifestyle factors.

Awareness of what causes cancer is the first step in making healthy behavior changes. And while living a healthier lifestyle is no guarantee that you won’t get cancer, it does make it less likely.

What causes cancer?

  • 78% of people who completed the ASCO survey correctly identified smoking and tobacco as a major risk factor for cancer. Each year, more than 480,000 people in the US die from illnesses related to tobacco use. About half of all Americans who smoke and don’t quit will die because of it.
  • But only 31% of respondents knew that obesity is a significant risk factor for cancer. Extra body weight is clearly linked to many cancer types including breast (in women past menopause), colon and rectal, endometrial, esophageal, kidney, and pancreatic cancers.

According to Colleen Doyle, MS, RD, managing director of nutrition and physical activity for the American Cancer Society, “After staying away from tobacco, maintaining a healthy weight is the next most important thing any of us can do to help lower our cancer risk.”

  • Only 38% of Americans knew that unhealthy food choices can raise cancer risk and only 30% knew that alcohol increased risk. The American Cancer Society recommends people eat at least 2½ cups of vegetables and fruits each day and for those who drink – limit alcohol to 1 drink a day for women and 2 for men.
  • Only 25% knew that lack of physical activity is a cancer risk factor. The American Cancer Society recommends adults get at least 150 minutes of moderate-intensity activity (equal to a brisk walk) or 75 minutes of vigorous-intensity activity (makes your heartbeat and breathing faster, and makes you sweat) each week, preferably spread throughout the week. A combination is OK too. 
  • More than half of respondents – 66% – knew that sun exposure is a risk. However, only 48% reported using sunblock to reduce their likelihood of getting skin cancer.
  • Only 20% of those who answered the survey knew that viruses can cause cancer. For example, human papillomavirus (HPV) causes most cases of cervical cancer, as well as many vaginal, vulvar, anal, penile, throat, and tongue cancers. HPV vaccination helps prevent HPV-related cancers.
  • A whopping 74% of respondents knew that family history and inherited factors can raise cancer risk. And while this is true, it is not what causes most cancer. In fact, only about 5% to 10% of all cancers are thought to result directly from problems with genes passed down from a parent.

What people worry about

  • About a third of Americans (32%) have a child, parent, brother, or sister who has been diagnosed with cancer.
  • More than 60% are concerned about getting cancer in their lifetime.
  • About half the people surveyed who said they have or had cancer are worried about being able to afford their treatment.
  • More than two-thirds of those who said they are responsible for paying for treatment for a family member who has or had cancer are worried about being able to afford it.
  • About a fourth of people worried about paying for cancer treatment have done something against doctors’ orders to cut costs, including skipping medical appointments; refusing treatment; postponing, skipping, or not filling prescriptions; and cutting pills in half.

"We should all be alarmed that Americans are potentially risking not only their health but also their lives due to high treatment costs," said ASCO Chief Medical Officer Richard Schilsky, MD, in a statement. "No patient or family member should have to face an impossible choice -- between their cancer treatment and food, shelter, clothing, and other necessary expenses."

What could be done

  • 91% of Americans say it is very or somewhat important that the federal government should dedicate substantial funding to diagnose, prevent, and treat cancer.
  • 92% think cancer drugs cost too much, and most believe the government should take actions to make them more affordable, including allowing Medicare to directly negotiate prices with prescription drug makers; speeding up US Food and Drug Administration approvals of generic versions of cancer treatments; regulating the price of cancer drugs to help lower costs; and making it legal for US residents to buy cancer drugs from pharmacies in other countries.

Overall, those who completed the survey expressed optimism and confidence about the long-term outlook for cancer. Seventy-nine percent thought most cancers would be curable within 50 years. 

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master’s-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

National Cancer Opinion Survey. Published online October 25, 2017 by the American Society of Clinical Oncology.


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