National ASCO Survey Finds Major Gaps in Americans' Knowledge of Cancer Prevention, E-Cigarettes, and End-of-Life Care

For immediate release
October 30, 2019


Kate Crawford

Only one in four Americans say they incorporate cancer prevention into their daily lives, according to the American Society of Clinical Oncology (ASCO)’s third annual National Cancer Opinion Survey. This low rate is despite research showing that as many as half of all cancer cases are preventable.[1] The survey found low levels of awareness of known cancer risk factors such as alcohol and obesity, and misconceptions among a substantial minority of Americans that artificial sweeteners and cell phones cause cancer in humans. The survey also revealed that nearly one in four young people (ages 18-38) believes e-cigarettes are harmless and not addictive, and three in 10 think flavored e-cigarettes are less damaging to a person’s health than non-flavored ones.

In addition, nine in 10 Americans say it is important for doctors and patients to take the time to discuss end-of-life care, but only one in four people with cancer have ever talked with their doctor about it. The National Cancer Opinion Survey is a large, nationally representative survey conducted online by The Harris Poll.

“Our survey helps us better understand Americans’ views on a range of cancer-related issues and exposes areas that are important to address,” said ASCO President Howard A. “Skip” Burris III, MD, FACP, FASCO. “This year’s findings raise concerns about the current state of cancer prevention in America, and strongly support the need for more education on the topic, beginning at a young age.”

This year’s national survey, commissioned by ASCO, was conducted online by The Harris Poll from July 9 to August 10, 2019, among 4,001 U.S. adults ages 18 and older and an oversample of 814 adults ages 18 and older with cancer for a total of 1,009 adults who have or had cancer. On September 24, ASCO released initial findings from the survey on e-cigarette usage and attitudes, which can be found here.

Few Americans are incorporating cancer prevention into daily life, despite concerns about developing the disease

Although six in 10 adults (57%) report being concerned about developing cancer in their lifetimes, only one in four (24%) say they care deeply about cancer prevention and incorporate risk reduction strategies into their daily lives. On the other hand, a quarter of Americans (25%) believe that there is nothing they can do to prevent cancer.

“Tobacco use, diet, sun exposure, alcohol consumption, and other lifestyle choices can have a major impact on people’s risk of developing many common cancers, or of cancer recurring,” said ASCO Chief Medical Officer Richard L. Schilsky, MD, FACP, FASCO. “While it’s never too late to make healthy choices, it’s most critical for young people to take action to reduce their cancer risk, since it can take decades for the disease to develop.”

By and large, Americans are uncertain where to find trusted information on what causes cancer – and misconceptions about cancer risk factors persist

Eight in 10 Americans (81%) believe there is a lot of information available about what causes cancer, but most have difficulty discerning what is credible. Two-thirds (66%) say they are unsure which sources to trust for information about what causes cancer, and a similar fraction say it is hard to know the most important things to do to reduce their risk of getting cancer.

Notably, a minority of Americans are aware of lifestyle factors that increase their cancer risk:

  • 36% realize obesity is a risk factor for cancer
  • 31% recognize alcohol is a risk factor for cancer

There are also misconceptions about factors that may cause cancer in people. For example, despite a lack of evidence:

  • 28% believe artificial sweeteners cause cancer
  • 16% believe cell phones cause cancer 
  • 9% believe caffeine causes cancer

Americans are more likely to get information about cancer prevention online than from their doctor, with 24% saying they have searched the web for information about how to reduce their cancer risk. One in five adults report talking to a doctor about their risk of developing cancer (22%) or what they should do to reduce it (18%).

“We urge every American to have regular conversations with their physician about reducing their risk of cancer and other chronic diseases,” said Dr. Burris. “If people want to supplement these conversations with online resources, they should look for sources that have been approved by doctors, such as ASCO’s patient information website, Cancer.Net.”

Trusted information about cancer prevention can also be found through The National Cancer Institute ( and the Centers for Disease Control and Prevention ( In addition, ASCO provides resources for physicians on cancer prevention at  

Most people affected by cancer aren’t discussing end-of-life care with their doctors, even though they believe it’s important

More than nine in 10 Americans (91%) believe it is important for doctors and patients to take the time to discuss end-of-life care.  However, few Americans affected by cancer say they or their loved one have ever discussed end-of-life care with a doctor:

  • 26% of people who have/had cancer
  • 22% of people who have/had a family member or loved one with cancer
  • 35% of caregivers to cancer patients

Most Americans are also not sharing their end-of-life wishes. Among those who have thought about end of life care (53%), one in four (25%) say they have never communicated their wishes to anyone, including family members.

“It’s critical to plan ahead for end of life care in the advanced stages of cancer or any disease,” said Dr. Schilsky. “Physicians and patients should discuss all of the available care options and develop a plan that reflects patients’ wishes and goals. This can ease the emotional and may even reduce the financial burden for patients and their loved ones.”

Resources for planning for end-of-life care, including a patient booklet, are available at Cancer.Net.

View the full set of findings from ASCO’s National Cancer Opinion Survey.


About ASCO: 

Founded in 1964, the American Society of Clinical Oncology, Inc. (ASCO®) is committed to making a world of difference in cancer care. As the world’s leading organization of its kind, ASCO represents nearly 45,000 oncology professionals who care for people living with cancer. Through research, education, and promotion of the highest-quality patient care, ASCO works to conquer cancer and create a world where cancer is prevented or cured, and every survivor is healthy. ASCO is supported by its affiliate organization, the Conquer Cancer Foundation. Learn more at, explore patient education resources at www.Cancer.Net, and follow us on FacebookTwitterLinkedIn, and YouTube.

About The National Cancer Opinion Survey:

ASCO's National Cancer Opinion Survey was established in 2017 by the American Society of Clinical Oncology (ASCO), in collaboration with The Harris Poll, to track the U.S. public’s views on cancer research and care. As the world’s leading organization of oncology professionals who care for people with cancer, ASCO believes it is critical to understand what the public, including patients, think of, expect, and need from the nation’s cancer care system. The poll, supported by the Mission Endowment of ASCO’s Conquer Cancer Foundation, is designed to be conducted annually to measure shifts in the public’s perceptions of a range of cancer-related issues over time.

This survey was conducted online in the U.S. by The Harris Poll on behalf of ASCO between July 9 – August 10, 2019 among 4,001 US adults aged 18+ and an oversample of 814 adults 18+ with cancer for a total of 1,009 adults with cancer. For all US adults age 18+, figures for age by gender, education, region, household size, marital status and employment status were adjusted, as needed, to population distributions from the US Census Bureau, separately for Hispanic, Black/African American (not Hispanic) and all other (not Hispanic).  The race/ethnicity groups were then combined into an overall total based on their proportion within the US adult population. The adults age 18+ with cancer were weighted separately, as needed, using population distributions from the CDC’s NHIS for those diagnosed with cancer, using the same demographic variables as above.

All sample surveys and polls, whether or not they use probability sampling, are subject to multiple sources of error which are most often not possible to quantify or estimate, including sampling error, coverage error, error associated with nonresponse, error associated with question wording and response options, and post-survey weighting and adjustments. Therefore, The Harris Poll avoids the words “margin of error” as they are misleading. All that can be calculated are different possible sampling errors with different probabilities for pure, unweighted, random samples with 100% response rates. These are only theoretical because no published polls come close to this ideal. Respondents for this survey were selected among those who have agreed to participate in online surveys. No estimates of theoretical sampling error can be calculated.