One in six cancer cases worldwide can be traced back to preventable or treatable infections, finds a new study. The data show that 2 million new cancers in 2008 were caused by such infections.
The study by French researchers looked at the incidence of 27 cancers in 184 countries in eight geographical regions. They calculated that in 2008, about 16% of cancers worldwide were infection-related, with the majority occurring in developing countries: 23%, versus 7.4% in developed nations.
The disparity in rates of infection-related cancers between geographical regions was stark, with 3.3% in Australia New Zealand, for example, compared with 32.7% in sub-Saharan Africa.
Most such cancers could be attributed to four infectious bugs: human papillomavirus (HPV), the stomach bacterium Helicobacter pylori, hepatitis B and hepatitis C. All four can be prevented or treated.
The sexually transmitted virus HPV, which is the leading cause of cervical cancer, can be prevented with a vaccine. The Centers for Disease Control and Prevention (CDC) recommends vaccination for boys and girls ages 9 to 26.
There’s also a vaccine for hepatitis B, which is recommended for everyone including infants. Hepatitis C infection can’t be prevented by vaccine, but it can be treated. Both viruses may contribute to cancers of the liver.
Infection with H. pylori, which can be found in gastric tumors, can also be treated with antibiotics.
The rates of infection-related cancers were similar between men and women, but the types of cancers were not: about half of such cancers among women were cervical or uterine, while more than 80% of infection-related cancers in men were liver or gastric cancer.
“Infections with certain viruses, bacteria, and parasites are some of the biggest and preventable causes of cancer worldwide,” said study authors Catherine de Martel and Martyn Plummer of the International Agency for Research on Cancer, in France, in a statement. They note that existing prevention methods like widespread vaccination, safer injection practices and antimicrobial treatments can help reduce infection.
In a corresponding editorial, Dr. Goodarz Danaei of the Harvard School of Public Health in Boston said, “Since effective and relatively low-cost vaccines for HPV and [hepatitis B] are available, increasing vaccine coverage should be a priority for health systems in high-burden countries.”
Further, maintaining a healthy lifestyle — practicing safe sex, for instance — eating a nutritious diet and exercising regularly can also keep infections at bay. Dr. William Schaffner, chair of preventive medicine at Vanderbilt University Medical Center in Nashville, told ABC News: “We have to remember that in our country behavioral risk factors still loom large. There are a number of strategies we can all employ to reduce our risk of cancer even more.”
The study was published in the journal The Lancet Oncology.