A different kind of cancer prevention: lowering infection rates

Most people don't think of cancer as a result of infection. However, a study just published in The Lancet Oncology has estimated that 16 percent of all cancer cases worldwide in 2008 were due to potentially preventable or treatable infections. In fact, of the 7.5 million cancer-related deaths that year, an estimated 1.5 million were caused by such communicable infections.

Led by researchers from the International Agency for Research on Cancer in France, the study involved a systemic analysis of data estimating rates of 27 different cancers in 184 countries. While the researchers' calculations indicate that about 16 percent all cancers in 2008 were infection-related, the fraction of such cancers was about three times higher in developing countries than in developed ones (22.9 percent vs. 7.4 percent). Out of the eight regions analyzed, sub-Saharan Africa s rate of 32.7 percent of all cancers being infection-related was the highest.

Four main infections were found to be responsible for the largest proportion of infection-related cancers: human papillomavirus (HPV), Helicobacter pylori, and hepatitis B (HBV) and C viruses (HCV). These infections together are estimated to be responsible for 1.9 million instances of cancer, most typically cervical, gastric, and liver cancers. Not surprisingly, cervical cancer (associated with HPV) accounted for roughly half of the infection-related incidence of cancer in women. In men, liver and gastric cancers comprised more than 80 percent of infection-related cancers.

These estimated rates, say researchers, are a call to action. As Dr. Goodarz Danaei from the Harvard School of Public Health writes in an accompanying commentary, there is a distinct potential "for preventive and therapeutic programs in less developed countries to significantly reduce the global burden of cancer and the vast disparities across regions and countries. He points to vaccines for HPV and HBV as "effective and relatively low-cost" means of preventing the infections that can lead to cancer. And the lead authors of the study add that safer injection practices and antimicrobial treatments should also be more effectively implemented.

ACSH's Dr. Gilbert Ross agrees. "Funding and public health initiatives to implement these preventive measures would obviously help to reduce the toll of infection-related cancer," he observes.

There are a number of examples of cancers caused by viruses, notes ACSH s Dr. Josh Bloom, and I expect that number to grow as the interaction of viral components with human DNA becomes better understood. In addition to those mentioned above, viruses are responsible for certain leukemias, lymphomas, and Kaposi s sarcoma, a skin cancer commonly found in AIDS patients before good therapies were developed.