High percentage of cancers potentially preventable

New estimates indicate that at least 40% of all cancer cases and nearly 50% of cancer deaths in adults aged 30 years or older in the United States can be attributed to potentially modifiable risk factors according to a study led by researchers at the American Cancer Society (ACS).¹

Based on 2019 nationally representative data on cancer incidence and mortality for 30 cancer types, the study found that more than 713,000 cancer cases and 262,000 cancer deaths could be attributed to modifiable factors.

“We already knew that a substantial number of cancer cases and deaths can be attributed to potentially modifiable risk factors, but still the number of cancer cases and deaths attributable to elevated factors is staggering,” says the lead author of the study, Farhad Islami, MD, PhD, who is the senior scientific director for the Cancer Disparity Research team at ACS. The study updates previous estimates based on 2014 data published in 2018.²

Modifiable risk factors included cigarette smoking (former or current smoking, including exposure to secondhand smoke), excess body weight, alcohol consumption, physical inactivity, diet (consumption of red and processed meat and low consumption of fruits, vegetables, dietary fiber, and dietary calcium), exposure to ultraviolet radiation, and infections (Epstein–Barr virus, Helicobacter pylori, hepatitis B virus, hepatitis C virus [HCV], human herpes virus 8, human immunodeficiency virus, and human papillomavirus [HPV]).

As in prior estimates, cigarette smoking was associated with the largest proportion of cancer cases attributed to risk factors (19.3%), and it was followed by excess body weight (7.6%), alcohol consumption (5.4%), ultraviolet radiation exposure (4.6%), and physical inactivity (3.1%).

Cigarette smoking emerged again as a critical risk factor to address, as it contributed to 22.7% and 15.8% of all cancer cases in men and women, respectively, and to 56% and nearly 40% of potentially preventable cancers, respectively. Dr Islami points to the continual high impact of cigarette smoking on cancer incidence and mortality and states that the study “clearly shows” the need to continue and enhance efforts to reduce smoking rates, particularly in populations such as low-income communities that have not benefited as much from the substantial progress made over the past decade to reduce these rates.

Scarlett Gomez, MPH, PhD, professor of epidemiology and biostatistics and coleader of the Cancer Control Program at the UCSF Helen Diller Family Comprehensive Cancer Center in San Francisco, California, also emphasizes this need. “While we have seen population-level prevalence of smoking decline, and consequent declines in lung and other tobacco-related cancers, smoking and secondhand smoke exposure still remain the largest contributors to cancer incidence and deaths.”

She says that the study highlights the challenge of reducing the population-level prevalence of major cancer risk factors such as smoking, and she agrees with the study authors on the need for a multilevel and multifactorial interventional approach that includes educating individual patients on the risks of cancer due to modifiable risk factors. Policy and community-level interventions also are needed to address the issues within the context in which patients live, work, and play that make it challenging to reduce risk behaviors.

A key takeaway from the study is the need to develop better strategies to reduce these risk factors associated with cancer incidence and death. Such strategies should include both education at the individual level and addressing the larger social and policy issues.

“Individual behavioral choices often occur within the context of the community,” says Dr Islami. “Therefore, in addition to attempts to reduce exposure to cancer risk factors at the individual level, community-level interventions with the engagement of public, private, and community organizations at local, state, and national levels are required to substantially reduce exposure to risk factors of cancer.”

How this may work in the case of smoking, for example, is for health care providers to offer guidance and help on smoking cessation measures, such as counseling and medications. Dr Islami notes that such measures need to be more affordable and accessible to all. Other measures can include tobacco control policies, such as tobacco taxation, smoke-free laws, warning labels, multimedia campaigns, and marketing bans, aimed at both encouraging current smoking individuals to quit and discouraging nonsmoking individuals from starting. He notes that among tobacco control policies, increasing the price of cigarettes through excise taxes has shown the strongest effect in the United States. Dr Gomez notes that the states with the sharpest declines in smoking rates are those that enacted tobacco policies, such as taxation and bans.

Increasing equitable access to preventive health care and awareness about prevention measures is also a critical part of a multifactorial strategy, Dr Islami says. He cites the recommendation by the US Preventive Services Task Force (USPSTF) to screen children and adolescents who are 6 years old or older for obesity and then to refer those children who could benefit for comprehensive, intensive behavioral interventions to promote a healthier body weight. He also cites the USPSTF’s recommendations for primary care providers to screen persons who are 18 years old or older for unhealthy alcohol use and to provide those engaged in risky or hazardous drinking with brief behavioral counseling interventions.

In addition, he points to the importance of educating patients (or parents of eligible children) on the recommendations for and benefits of HPV vaccination as well as HCV testing and treatment. HPV vaccination is particularly important, as cervical cancer is potentially 100% preventable with the vaccine.

Elena Martinez, MPH, PhD, the Sam M. Walton Endowed Chair for Cancer Research at the UC San Diego Moores Cancer Center and a professor in the Department of Family and Preventive Medicine at the Herbert Wertheim School of Public Health and Human Longevity Science in La Jolla, California, emphasizes the need to ensure that patients are up to date on vaccinations and underscores that all cancer prevention strategies will need to be specific to the risk factor profile of the individual patient given the unequal burden of cancer in low-income and minoritized communities.