An oncolytic virus is a virus that preferentially infects and kills cancer cells. As the infected cancer cells are destroyed by oncolysis, they release new infectious virus particles or virions to help destroy the remaining tumour.

Viruses, infections and cancer When viruses cause an infection, they spread their DNA, affecting healthy cells’ genetic makeup and potentially causing them to turn into cancer. HPV infections, for instance, cause the virus’ DNA to combine with the host’s DNA, disrupting the normal function of cells.

A more recent, but equally serendipitous, discovery involves a child in Uganda with Burkitt’s lymphoma who, in 1971, went into remission after he contracted measles. In the 1990s, researchers in Canada found that a common virus called reovirus destroyed infected cancer cells.

The most common adverse effects of OV therapy have been transient flu-like symptoms, as might be expected from a viral infection. These do not overlap with the toxicities of chemotherapy and/or radiotherapy, so that the further development of combination strategies is unlikely to be limited by toxicity.

Viruses generally have specific host cells which they infect. Some virus types are associated with specific cancers and can convert normal cells into cancer cells. Examples of viruses associated with cancer are: papillomavirus-cervical cancer, hepatitis virus-liver cancer, Epstein-Barr virus-Burkitt’s lymphoma.

Cancer is also a complex disease with many factors that can affect its development. This makes it tricky to say that a virus directly causes cancer. It’s more accurate to think of viruses as one contributing factor in the development of cancer.

Today, we now know that about 15%-20% of cancers have a viral cause, including Burkitt’s lymphoma (Epstein-Barr virus), cervical cancer (human papillomavirus), and liver cancer (hepatitis B and C viruses). If, by the 1960s, viruses were accepted as a contributing cause of cancer, the same could not be said of bacteria.

There are no cures for any kinds of cancer, but there are treatments that may cure you. Many people are treated for cancer, live out the rest of their life, and die of other causes. Many others are treated for cancer and still die from it, although treatment may give them more time: even years or decades.

The 7 Viruses That Cause Human Cancers

• Epstein-Barr Virus: Burkitt’s Lymphoma, Hodgkin’s Disease, and Nasopharyngeal Carcinoma.
• Kaposi’s Sarcoma-Associated Herpesvirus: Kaposi’s Sarcoma, Primary Effusion Lymphoma, Multicentric Castleman’s Disease.
• Human Adult T-cell Leukemia Virus Type 1 (HTLV-1): T-cell Leukemia.

Some infections can cause long-term inflammation in a part of the body. This can lead to changes in the affected cells and in nearby immune cells, which can eventually lead to cancer. Some types of infections can suppress a person’s immune system, which normally helps protect the body from some cancers.

With the exception of blood cancers, blood tests generally can’t absolutely tell whether you have cancer or some other noncancerous condition, but they can give your doctor clues about what’s going on inside your body.

Bacterial infections traditionally have not been considered major causes of cancer. Recently, however, bacteria have been linked to cancer by two mechanisms: induction of chronic inflammation and production of carcinogenic bacterial metabolites.

Signs of Cancer

• Change in bowel or bladder habits.
• A sore that does not heal.
• Unusual bleeding or discharge.
• Thickening or lump in the breast or elsewhere.
• Indigestion or difficulty in swallowing.
• Obvious change in a wart or mole.
• Nagging cough or hoarseness.

When cancer spreads, it’s called metastasis. In metastasis, cancer cells break away from where they first formed, travel through the blood or lymph system, and form new tumors in other parts of the body. Cancer can spread to almost anywhere in the body. But it commonly moves into your bones, liver, or lungs.

Cancer cells differ from normal cells in many ways. For instance, cancer cells: grow in the absence of signals telling them to grow. Normal cells only grow when they receive such signals.

Cancer is NOT contagious You cannot “catch” cancer from someone else. Close contact or things like sex, kissing, touching, sharing meals, or breathing the same air cannot spread cancer. Cancer cells from someone with cancer are not able to live in the body of another healthy person.

Table 1Common sites of metastasis for different primary sites

Where Cancer Spreads

For cancer, invasion is the direct extension and penetration by cancer cells into neighboring tissues. It is generally distinguished from metastasis, which is the spread of cancer cells through the circulatory system or the lymphatic system to more distant locations.

In some situations, metastatic cancer can be cured, but most commonly, treatment does not cure the cancer. But doctors can treat it to slow its growth and reduce symptoms. It is possible to live for many months or years with certain types of cancer, even after the development of metastatic disease.

I. Metastasis is the general term used to describe the spread of cancer cells from the primary tumor to surrounding tissues and to distant organs and is the primary cause of cancer morbidity and mortality. It is estimated that metastasis is responsible for about 90% of cancer deaths.

If a metastasis lands near or inside these structures, then it may simply block, squeeze, or crush these parts in a way that can be devastating. For example, a metastatic tumor may block an airway or press on the part of the brain that controls breathing.

Metastasis. In metastasis, cancer cells break away from where they first formed (primary cancer), travel through the blood or lymph system, and form new tumors (metastatic tumors) in other parts of the body. The metastatic tumor is the same type of cancer as the primary tumor.

There is no one test to check for metastasis. Various tests will reveal different things. The tests that are done are determined by the type of primary cancer and/or any symptoms that need to be investigated. Routine blood tests such as liver enzymes may be elevated in the presence of liver metastasis.

Metastasis is the spread of cancer cells to new areas of the body, often by way of the lymph system or bloodstream. A metastatic cancer, or metastatic tumor, is one that has spread from the primary site of origin, or where it started, into different areas of the body.

And they are deadly. In a surprise finding that was recently published in Nature Communications, Weizmann Institute of Science researchers showed that nighttime is the right time for cancer to grow and spread in the body.

If the cell learns how to block that, and it develops the ability to proliferate, tumors grow more rapidly.” Some of these mutations lead to rapid, unchecked growth, producing tumors that may spread quickly and damage nearby organs and tissue.

It takes at least 30 divisions of one cancer cell to create a tumor that is 1 centimeter in size (about half an inch). That is the smallest size likely to be seen on an X-ray. It takes about three to six months for most lung cancers to double their size.

A cyst is a sac or capsule that’s filled with tissue, fluid, air, or other material. A tumor is usually a solid mass of tissue.