You may already know that smoking and genetics can raise your cancer risk. But did you know some viruses can, too? 

While less common, viruses are responsible for 15% to 20% of cancers worldwide. The good news: You can take steps to protect yourself, including getting vaccinated and reducing exposure. 

We spoke with Ashley Volaric, MD, a pathologist at University of Vermont Medical Center, about four viruses that can increase your cancer risk — and how to stay safe. 

1. Human papillomavirus (HPV)

• Vaccine available: Yes
• Linked to: Cervical, head and neck, anal cancers
• Spread by: Skin-to-skin contact, primarily through sexual activity 

HPV is the most common sexually transmitted infection in the United States, with about 13 million new cases each year. It can cause genital warts and, in some cases, lead to cancer. 

“The vaccine works extremely well,” Dr. Volaric says. “It should be marketed as an anti-cancer vaccine.” She recommends vaccination for all children at age 11 or 12, and for adults up to age 26 — regardless of gender. 

2. Epstein-Barr virus (EBV)

• Vaccine available: No
• Linked to: Lymphoma, stomach and throat cancers
• Spread by: Saliva and other bodily fluids 

EBV is one of the most common viruses worldwide. Most people are infected by adulthood, often without symptoms. It’s the virus behind mono, and while rare, it can increase cancer risk. 

“If your child gets mono, there’s no need to panic,” Dr. Volaric says. “It may even be better to acquire the virus young, when the immune system is stronger.” 

To reduce risk, avoid close contact with people who have active EBV infections. 

3. Hepatitis B (HBV)

• Vaccine available: Yes
• Linked to: Liver cancer
• Spread by: Blood, semen and other body fluids 

Hepatitis B is a serious liver infection. While many cases are short-term, chronic HBV can lead to liver cancer and cirrhosis. 

“The best way to prevent hepatitis B is to get vaccinated,” Dr. Volaric says. Vaccines are routinely given to infants, and adults ages 19 to 59 should complete the series if they haven’t already. 

4. Hepatitis C (HCV)

• Vaccine available: No
• Linked to: Liver, head and neck cancers, non-Hodgkin lymphoma
• Spread by: Blood-to-blood contact, often through injection drug use 

Hepatitis C is a serious liver infection that can become chronic and deadly if untreated. Cases have surged in recent years, largely due to injection drug use. 

Adults 18 and older should get screened at least once, and pregnant women should be tested during each pregnancy. People with ongoing risk factors need regular testing. 

What About HIV and Other Viruses? 

People with compromised immune systems — such as those living with HIV — are at higher risk for virus-related cancers, including non-Hodgkin lymphoma and cervical cancer. Rare cancers linked to viruses may also appear in immunocompromised individuals. 

“A compromised immune system can let a virus go unchecked,” Dr. Volaric says. “Even if your immune system is healthy, there are ways you can protect yourself.”