It’s impossible to predict exactly who will and who won’t get cancer — but there are certainly factors that we know increase our risk, like family history and smoking.
Also upping your odds? Certain illnesses. And they account for more cancer cases than you might think.
A new study published in “The Lancet Oncology” suggests that a staggering 2.3 million new cancer cases around the world in 2024 — or 12% of all new cancer cases — can be attributed to infectious diseases.
These are extremely common diseases — one affecting 90% of people around the world — that are contributing to cancer development. The good news is that we can take action to avoid all of these infections.
“Our findings highlight the importance of infection control to achieve cancer prevention,” the researchers from the International Agency for Research on Cancer in Lyon, France, wrote. This includes vaccination, scanning, testing and treatment, safe injection and sex practices.
Here’s what researchers found.
1. The stomach bug H. pylori
An estimated 760,000 or 4% of all cancer cases in 2024 could be traced back to the stomach bug Helicobacter pylori, the new study found.
More than half the people in the world may get an H. pylori infection in their life. It spreads through contact with an infected person’s saliva, vomit or stool — or through contaminated surfaces, food and water.
For many people, the bacteria doesn’t cause any symptoms, but it can cause swelling of the stomach lining or peptic ulcer (an open sore on the stomach lining). This can cause burning pain, upset stomach, burping, bloating, and loss of appetite and weight loss.
This long term inflammation and toxins from bacteria can damage cells, leading to stomach cancer.
To avoid H. pylori, wash your hands, eat food that’s been prepared and cooked in a clean space, and if you or someone in your household gets infected, finish prescribed antibiotics.
2. HPV
Human papillomavirus (HPV) accounts for 750,000 new cancer cases globally. It causes almost all cervical cancers but can also cause throat, anal, vulvar, penile and vaginal cancers.
These infections are often passed through sex or through other skin-to-skin contact, and may produce warts.
The great news is that we have a very effective vaccine that protects against 90% of HPV cancers, but it must be administered on time. The American Cancer Society recommends all children get it between ages 9 and 12, but young adults up to age 26 who haven’t yet gotten it should do so as soon as possible.
Outside vaccines, practice safe sex and routine cervical screenings for women help reduce risk of infection and development into cancer.
3. Hepatitis B
An estimated 360,000 cases of cancer (2%) of new cases can be attributed to the liver infection hepatitis B.
For most people, an hepatitis B infection is short — but when it lasts more than six months, it becomes chronic and raises risk of liver cancer, liver failure and serious scarring of the liver (cirrhosis).
An acute infection might look like abdominal pain, dark urine, fever, joint pain and jaundice.
Like HPV, there’s a highly affective hepatitis B vaccine available. The CDC recommends it for infants, children who haven’t yet been vaccinated, adults 19-59, and older adults if they’re at additional risk. Outside the vaccine, using condoms also reduces risk of hepatitis B.
4. Epstein-Barr Virus (EBV)
About 260,000 cases of cancer (1%) can be attributed to EBV, researchers found.
EBV is one of the most common viruses in the world — about 90% of people in the world have been caught it. It’s the main cause of mononucleosis aka “mono” or “the kissing disease.”
Its symptoms look like other common illnesses: fatigue, fever, inflamed throat, swollen lymph nodes.
Catching EBV can increase risk of getting cancer of the upper throat (nasopharyngeal cancer). EBV has also been linked to lymphoma and stomach cancer.
It spreads through bodily fluids, primarily saliva — so avoid this disease by not kissing, sharing drinks or food, or personal items like toothbrushes with folks who are infected.
5. Hepatitis C
About 160,000 cases (less than 1%) of cancer cases can be attributed to hepatitis C.
This virus spreads through infected blood, often shared needles, potentially causing serious liver damage that leads to cancer.
There is no vaccine available for this virus, but it is curable with medication.
Avoid this virus by practicing safe sex, vetting any body piercing and tattoo shops for safety practices, and stopping use of illegal injection drugs.
