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Germs and cancer: What’s the connection?

Although genetics, lifestyle habits, smoking and hormone therapy may get most of the attention when doctors look for causes of cancer, mounting evidence suggests certain germs can play a role, too.

Already, scientists have determined that the human papillomavirus (HPV) is responsible for more than 90 percent of cervical cancer, and other malicious bugs are strongly suspected in certain forms of stomach, lymphatic, liver and blood cancers.

Is cancer infectious?

Of course, cancer itself can’t be transmitted under any circumstances. But culprit viruses and bacteria are passed from person to person, causing infectious, noncancerous diseases. These illnesses sometimes lay the groundwork for cell and tissue damage that might someday become malignant.

Fortunately, most people fight off germs and never develop malignancies. But in others, having had a bout with certain viruses and bacteria appears to trigger other processes that lead to the start of cancer. For example, the chance of developing cancer after being infected by the Epstein-Barr virus—which triggers infectious mononucleosis—is tiny. Yet the fact remains that the virus ever so slightly elevates a person’s risk for lymphoma and nasal cancer.

Other bad germs

Several other kinds of cancer are associated with, or seem somehow related, to germs, such as:

  • Leukemia and lymphoma, associated with the human T-cell leukemia/lymphoma virus 1. The germ is a so-called retrovirus; these agents cause leukemia in animals. In humans, the virus is passed primarily by sexual activity or blood contact.
  • Kaposi’s sarcoma, an uncommon cancer of the blood vessels, thought to be advanced by the human herpes virus 8 (HHV 8), a relative of viruses that cause cold sores and genital herpes.
  • Non-Hodgkin’s lymphoma, a group of cancers of the lymphatic system sometimes associated with human immunodeficiency virus (HIV). This disease weakens the immune system and also plays a role in cases of Kaposi’s syndrome (in men only) and cervical cancer.
  • Hepatocellular carcinoma (liver cancer), which develops in one out of four cases of viral hepatitis B and C.
  • Stomach cancer, thought to develop when Helicobacter pylori bacteria interacts with nitrates, nitrites and cured meat and causes a precancerous condition called chronic atrophic gastritis (inflammation of the inner stomach lining).

Vaccine hopes

A vaccine is now available that protects against the four strains of HPV that cause 70 percent of cervical cancers. The U.S. Centers for Disease Control’s Advisory Committee on Immunization Practices recommends this vaccine for females ages 11 to 26. Hepatits B can also be prevented by vaccination. And although no surefire way of preventing all infections is likely to be discovered, you can reduce your risk of exposure to these germs by avoiding risky behaviors and seeing your doctor if you develop any worrisome symptoms such as fatigue, weight loss, unusual pain or unfamiliar skin marks or tissue lumps.