Q Why do some viruses cause cancer?

— Molly Torinus

A Mark Horswill, virology lab research technician at the Morgridge Institute for Research:

Infectious agents — both bacterial and viral — are responsible for about 25 percent of all human cancers. There are about seven known viruses that cause human cancers.

The two that are most well known are hepatitis B and C, which cause liver cancer, and human papillomavirus (HPV), which causes cervical cancer.

The link between viruses and cancer is not very direct. Cancer is, by definition, uncontrolled cell growth. Uncontrolled cell growth is a rather broad term for the complex process of a cell going from a normal state to a cancerous state.

The virus infection does not by itself cause cancer, but can interfere with a cell’s normal maintenance of things. For example, the cell’s ability to repair itself will be hindered by products from the virus.

As more and more changes develop over time, these changes cause a transformation of the cell that we would then deem as cancer.

HPV research has been a great success over the last 40 years because the scientific community found that a certain cancer, cervical cancer, is caused by a particular virus, HPV. Not only did scientists discover this, they were able to develop a vaccine.

If you get this vaccine before you’re exposed to HPV, it greatly reduces the chances of cancer when exposed to the virus.

Overall, the ultimate goal when it comes to viruses and cancer is to effectively diagnose, treat and prevent all cancers caused by viruses.

Blue Sky Science is a collaboration of the Wisconsin State Journal and the Morgridge Institute for Research.