Top 7 Viruses That Can Lead to Cancer You Should Know

The effects of certain viruses on the body cause cells to lose control and turn into malignant tumors. Studies show that more than one hundred thousand cases of cancer in the world are caused by viruses.

There are at least seven viruses known to directly or indirectly cause cancer , according to Live Science. They include: human papillomavirus (HPV), hepatitis B virus (HBV), hepatitis C virus (HCV), Epstein-Barr virus (EBV), herpes viruses, human T-cell lymphotropic virus, and Merkel cell papillomavirus.

Illustration of cancer cells. (Photo: MD Anderson Cancer Center).

Additionally, human immunodeficiency virus (HIV) increases the risk of cancer by 'opening the door' for cancer-causing viruses to enter the body.

Estimates of viral infections in 2012 showed that viruses caused 10% of the 1.4 million cancers worldwide. Dr. Jay Berzofsky, a senior researcher at the American Cancer Institute, explained that viruses can cause cancer through direct and indirect mechanisms. Each virus can cause cancer in its own way.

Direct mechanism

One of the most well-known cancer-causing viruses is HPV . HPV causes 37,000 new cases of cancer each year. It is known to contribute to the development of cervical, anal, pharyngeal, penile, vaginal, and vulvar cancers.

Some HPV viruses promote cancer by turning healthy cells into tumor cells. HPV produces bad proteins that disable the natural tumor suppression system of normal cells . 'This allows tumors to grow wildly ,' said Dr. Harrys Torres, professor of infectious diseases at the University of Texas MD Anderson Cancer Center in the US.

There are more than 200 types of HPV, but only 12 are strongly linked to cancer .

The HPV virus causes 37,000 new cases of cancer each year, according to Live Science. (Photo: Shutterstock).

EBV and human T-cell lymphotropic virus also cause cancer directly. They act through different genetic mechanisms but lead to the same result: cancer cells multiply rapidly and evade the body's defenses.

Many factors determine whether these viruses can cause cancer. For HPV and EBV, some strains are more likely to cause cancer than others.

People with weakened immune systems are also more susceptible to cancer caused by viruses. External factors can increase the likelihood of developing tumors, such as mutations or exposure to carcinogens.

Indirect mechanism

Viruses can indirectly cause cancer. HBV and HCV are two strains of the virus that cause chronic infections that lead to long-term inflammation, cirrhosis, or scarring of the liver. 'Chronic inflammation has a high risk of causing cancer ,' says Dr. Berzofsky.

As the body tries to repair damage from HBV and HCV by creating new liver cells, those cells can mutate and develop into cancer. HCV is also linked to non-Hodgkin lymphoma, a cancer of the lymphatic system caused by the virus continually stimulating the immune system.

Meanwhile, HIV increases the risk of developing cancer through an indirect mechanism. This virus does not cause chronic inflammation but weakens the immune system. From there, the body is susceptible to direct attacks by cancer-causing viruses.