These Germs Are a Major Cancer Risk, New Report Highlights

Some of the worst germs out there aren’t just making us sick for a short while—they’re also laying the groundwork for cancer. A new report from scientists at the American Association for Cancer Research highlights the risk posed by four viral and bacterial threats in particular: human papillomavirus (HPV), hepatitis B (HBV), hepatitis C (HCV), and Helicobacter pylori. Importantly, these pathogens can be effectively prevented with vaccines or treated with medication, the researchers say.

On Wednesday, the AACR released the 14th edition of its annual Cancer Progress Report, which complies the latest data on cancer incidence, mortality, and survivorship in the U.S. The report also dives into the known and preventable causes of cancer, including viruses and bacteria, and how efforts to address these risk factors have progressed over time.

According to research collected by the AACR, about 3.4% of all cancer cases in the U.S. annually can be attributed to germs; worldwide, this extends to 13% of all cancers, or about one in every eight cases. There are many viruses and bacteria that can theoretically spark cancer through various mechanisms, such as changing how some cells behave, weakening our immune system, or by causing chronic inflammation. But the report focuses on HPV, HBV, HCV, and H. pylori due to their outsized impact. All told, these four are estimated to account for over 90% of germ-related cancers globally.

Chronic HBV and HCV infection both help cause liver cancer. H. pylori can trigger stomach cancer. And HPV not only causes nearly all cervical cancer cases in women, but also causes the majority of penile cancer cases in men as well as most anal, throat, and mouth cancers in both men and women. A fifth germ, Epstein-Barr virus (EBV), is also thought to be a major contributor to several cancers, such as Hodgkin’s lymphoma. However, unlike the others listed above, EBV isn’t currently preventable with vaccines, nor are there specific treatments for it (most people are exposed to EBV in their lifetime, but only a few seem to experience acute symptoms, and even fewer develop long-term complications as a result).

HBV and most of the cancer-causing strains of HPV can be prevented with highly effective vaccines, while there are now highly effective medications that can cure chronic HCV infections. H. pylori, a common cause of stomach ulcers, can be treated with antibiotics and stomach acid-reducing drugs. But while there has been some recent successes made in ensuring that people have access to these vaccines and drugs, far too many people still aren’t getting them, the AACR researchers say. About only two-thirds of eligible children and teens had received the recommended two doses of the HPV vaccine in 2022, for instance.

The AACR report also details the significant progress we’ve made in both diagnosing and treating cancer over the years, even treating cases that would have been unsalvageable a decade earlier thanks to new advances in immunotherapy. But about 40% of cancers in the U.S. are associated with these germs and other modifiable risk factors, such as alcohol consumption. And much more needs to be done to keep cancer on the run, the report authors say.

“In recent years, we have witnessed extraordinary advances against cancer. To maintain this pace of progress for patients, robust and sustained funding for cancer research must remain a national and congressional priority,” said AACR CEO Margaret Foti, in a statement from the AACR.