Is cancer contagious?

Yes, cancer is contagious.

But lest you panic and over-react, it is good to keep in mind that you can’t catch cancer like you can easily catch a cold.

“There is emerging evidence of viral and bacterial triggers in cancer,” says Dr. Ian Frazer, a distinguished scientist best known for his work on the development of the cervical cancer vaccine that protects against the human papillomavirus (HPV.) He was in Manila as part of the Australian Embassy’s “Scientists in Schools” initiative that seeks “to build existing efforts in increasing appreciation for the importance of science, technology, and innovation.” 

But Dr. Frazer points out that although viruses have been implicated to cause certain kinds of cancer, these cancers cannot be caught like one catches the usual infections. Rather, the viruses cause genetic mutations in cells, thereby increasing the likelihood that these will become cancerous. And thus, it is more accurate to say that we can catch infections that can potentially trigger certain types of cancers.

What are the cancers caused by a viral trigger? Apart from HPV that causes cervical cancer in women or oropharyngeal and non-melanoma skin cancers in both sexes, the hepatitis B and C viruses have been strongly implicated as causing primary liver cancer. In addition, the Epstein-Barr virus, which causes infectious mononucleosis (commonly called the “kissing disease”), is associated with Burkitt’s lymphoma (a cancer of the lymphatic system), nasopharyngeal cancers, Hodgkin’s disease (a lymphatic cancer that is the fourth most common cancer in kids), and even invasive breast cancer. In addition, Helicobacter pylori is a bacteria that causes hyperacidity, indigestion, ulcers, and even stomach cancer.

A film called Catching Cancer that features the work of Dr. Frazer, along with other scientists, even opens up the possibility that a virus that infects the common house mouse called MMTV (mouse mammary tumor virus) is linked to breast cancer in humans. Dr. Frazer emphasizes the importance of ongoing research, “Through research you can make significant inroads to help society. We do not do research in isolation. We do it in collaboration with other scientists, and we do it for the world.”

But why focus on cancer? “It is the inevitable consequence of aging where incidence increases with age,” says Dr. Frazer. “The future challenge in medicine is non-infective chronic disease. While the good news is that we are living longer, a consequence is that we become prone to diseases. With some effort, we can prevent over 70 percent of cancers and cure over 50 percent of these.”

While the viral or bacterial triggers for cancer exist, “70 to 90 percent of all cancers are environmental,” adds Dr. Frazer. “Lifestyle-related factors are the most important and preventable among the environmental exposures.”

Frazer continues, “Tobacco consumption will account for 50 percent of all cancers in men; dietary practices and reproductive or sexual practices will account for 20-30 percent of cancers.”

Obesity is a risk factor and being 20-percent overweight translates to a 50-percent increase in the risk for breast cancer. Excessive alcohol intake can also increase incidence of mouth, liver, esophageal, stomach, breast, and pharyngeal cancers; excessive sun exposure increases the predisposition for skin cancers. To counter the menace of cancer, carotenoids in vegetables and fruits have been shown to have substantial anti-cancer properties in various intervention studies.

“Changes in lifestyle can reduce mortality and morbidity,” asserts Dr Frazer. “The easiest thing to do for cancer control is to prevent it.” And although multiple agents cause the disease, we can avoid catching the viral infections that can trigger cancer.

For cervical cancer protection, the eminent Australian immunologist recommends that girls as young as nine years old be immunized with the HPV vaccine. He concludes, “Vaccines are only effective if they are used.”