Brock University medical microbiologist Ana Sanchez estimates up to 20% of all cancers are caused by infectious agents, including some parasites.

The news coming out of the World Health Organization (WHO) this week is bleak: cancer around the globe is growing “at an alarming pace.”
The bulk of this – at least 60 per cent – is occurring in low-income countries.

The common contributors to cancer are well known: smoking; unhealthy diet; a sedentary lifestyle; stress. But … parasites?

“It’s been estimated that up to 20 per cent of all cancers are caused by infectious agents, including some parasites,” says Brock University medical microbiologist Ana Sanchez.

Bacterial and viral infections such as Hepatitis B and C, H. pylory and others have been identified as contributing factors in such cancers as lymphoma, sarcoma, liver cancer and cervical cancer.

In the case of parasites, Opisthorchis viverrini and Clonorchis sinensis (liver flukes) are linked to an increased risk of developing cancer of the bile ducts, while infection with Schistosoma haematobium has been linked to bladder cancer.

“It is really important that health systems deal with parasites and infections, which results not only in the prevention of certain cancers but also healthier populations,” says Sanchez, an associate professor in the Faculty of Applied Health Sciences.

Sanchez’s comment echoes that of Christopher Wild, director of the WHO’s International Agency for Research on Cancer and co-author of “World Cancer Report 2014,” released Feb. 3.

“The rise of cancer worldwide is a major obstacle to human development and well-being,” Wild says in a press release. “These new figures and projections send a strong signal that immediate action is needed to confront this human disaster, which touches every community worldwide, without exception.

“In low- and middle-income countries, it is critical that governments commit to enforcing regulatory measures to protect their populations and implement cancer prevention plans.”

Sanchez says many low-income countries are hit by the “double burden” of infections that have been around for a long time coupled with non-communicable diseases such as cancers and diabetes.

Epidemiologist Martin Tammemagi says that, in low-income countries, smoking is becoming an increasing cause of lung cancer.

“Tobacco company activities are being curtailed in the developed world, so tobacco companies are very strongly marketing to developing countries, and they are causing an alarming rise in smoking in developing countries,” he says.

“Now lung cancers and other smoking-related cancers are starting to rise in the developing world,” he says. “The smoking-associated cancers, which are preventable, are expected to create a very large global burden of cancer in the future.”

Tammemagi has created risk calculation software that can reduce surgical procedures by helping doctors know if nodules showing up on CT lung scans have a high probability of being cancerous.

The “World Cancer Report 2014” was released on the eve of World Cancer Day. Major findings include:

• in 2012, the worldwide burden of cancer rose to an estimated 14 million new cases per year, a figure expected to rise to 22 million annually within the next two decades;
• over the same period, cancer deaths are predicted to rise from an estimated 8.2 million annually to 13 million per year;
• overall, about two million (16 per cent) of the total of 12.7 million new cancer cases in 2008 are attributable to infections. This fraction varies 10-fold by region; it is lowest in North America, Australia, and New Zealand (close to 4 per cent) and highest in sub-Saharan Africa (33 per cent)
• as a consequence of growing and ageing populations, developing countries are disproportionately affected by the increasing numbers of cancers. More than 60 per cent of the world’s total cases occur in Africa, Asia, and Central and South America, and these regions account for about 70 per cent of the world’s cancer deaths

“The implementation of effective vaccination against hepatitis B virus and human papillomavirus can markedly reduce cancers of the liver and cervix, respectively,” says the report.

“Preventing the spread of tobacco use in low- and middle-income countries is of crucial importance to cancer control.”