Smoking, diet, UV exposure contributing to 44% of cancer deaths

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Potentially modifiable risk factors – such as smoking and diet – could be contributing to an estimated 40% of all cancers, and up to 44% of cancer deaths, among patients aged 30 years and older.

Cigarette smoking remains the leading risk factor contributing to cancer cases (19.3%) and deaths overall (28.5%), according to a new study, “Proportion and number of cancer cases and deaths attributable to potentially modifiable risk factors in the United States, 2019.”

Other factors: secondhand smoke; excess body weight; alcohol consumption; eating red and processed meats, but not enough fruits, vegetables, fiber and calcium; physical inactivity; exposure to ultraviolet radiation; and seven carcinogenic infections.

“Despite considerable declines in smoking prevalence during the past few decades, the number of lung cancer deaths attributable to cigarette smoking in the United States is alarming,” corresponding author Farhad Islami, MD, PhD, said in an accompanying news release. “This finding underscores the importance of implementing comprehensive tobacco control policies in each state to promote smoking cessation, as well as heightened efforts to increase screening for early detection of lung cancer, when treatment could be more effective.

“Interventions to help maintain healthy body weight and diet can also substantially reduce the number of cancer cases and deaths in the country, especially given the increasing incidence of several cancer types associated with excess body weight, particularly in younger individuals,” said Islami, who is senior scientific director for cancer disparity research at the American Cancer Society.

By the numbers

The study used pre-pandemic figures from 2019 to avoid distortion of results when cancer diagnoses slowed, work and health insurance coverage was disrupted, and patients at times feared going to physicians’ offices and hospitals, due to the COVID-19 pandemic in 2020. The researchers excluded nonmelanoma skin cancers.

Cigarette smoking contributed to 344,070, or 19.3% of all cases of cancer. It was a factor in 56% of all potentially preventable cancers in men and 39.9% of cancers in women.

Excess body weight was the second leading factor, contributing to 7.6% of all cases. Alcohol consumption added to 5.4% of cases, while UV exposure contributed to 4.6% of cases and physical activity was a factor in 3.1% of cases.

Also included among risk factors were infection with Epstein–Barr virus (EBV), Helicobacter pylori, hepatitis B virus (HBV), hepatitis C virus (HCV), human herpesvirus-8 (HHV-8; also called Kaposi sarcoma herpesvirus), human immunodeficiency virus (HIV), and human papillomavirus (HPV).Those contributed to 3.4% of all cancer cases, according to the study.

Types of cancer

Based on types of cancer, the researchers estimated 100% of cervical cancer was caused by potentially modifiable risk factors. At least 80% of oral cavity, esophagus, trachea, lung and bronchus, and larynx cancerts, and at least 90% of anal and skin cancers were attributable to the risk factors, according to the research.

“These findings show there is a continued need to increase equitable access to preventive health care and awareness about preventive measures,” senior author Ahmedin Jemal, DVM, PhD, said in the news release. Jemal is senior vice president of surveillance and health equity science at the American Cancer Society.

“Effective vaccines are available for hepatitis B virus, that causes liver cancer and HPV, which can cause several cancer types, including cervical, other anogenital, and oropharyngeal cancers,” Jemal said. “Vaccination at the recommended time can substantially reduce the risk of chronic infection, and consequently, cancers associated with these viruses. HPV vaccination uptake in the United State is suboptimal.”

What comes next

The study noted tobacco control programs can have the greatest effect on reducing cancer cases and deaths, with price hikes on cigarettes the most effective method in the United States. The U.S. surgeon general has suggested raising retail prices to at least $10 a pack; as of 2019, cigarette prices were $10 a pack in two states and Washington, D.C. There is wide variation across the states in implementing measures such as smoke-free laws, assistance with quitting, warning labels, media campaigns, and marketing bans.

Smoking cessation programs and lung cancer screening for high-risk current and former smokers also remain underutilized around the nation, the study said.

For diet and exercise, “the combination of excess body weight, alcohol consumption, dietary factors, and physical inactivity contributed to the largest proportion of all cancer cases in women (nearly one fourth of all cases) and was second only to tobacco smoking in men (one sixth of all cases),” the study said.

“These findings suggest that maintaining a healthy body weight, cessation or limiting alcohol consumption (for those who drink), consuming a healthy diet, and being physically active can substantially reduce the number of cancer cases and deaths in the United States,” the study said.

Over time, smoking rates for people generally have gone down in the United States, but the researchers said obesity and severe obesity has been increasing in recent decades. An estimated 42% of adults aged 20 years and older, and 20% of adolescents aged 2 to 19 years, are dealing with obesity, the study said. Meanwhile, more than half of adults aged 21 years and older consumed alcohol in the last month, but just 12% of people aged 18 years and older met consumption recommendations for fruits and vegetables, as of 2021.

Potential solutions range from making healthier food options available in schools, workplaces and public places, to taxing sugar-sweetened beverages, to building out infrastructure such as parks to promote physical activity, to physicians screening for obesity.

Limiting sun exposure in daytime and wearing protective clothing and sunscreen can reduce potential risk cause by ultraviolet light. For infections, vaccinating for HPV and screening for cervical cancer would help reduce risk, the study said.