Infections Causing Human Cancer

Infections Causing Human Cancer by Harald Zur Hausen provides an excellent overview of the role of chiefly viruses and the Helicobacter group of bacteria in the development of human cancers. The book is aimed at introducing the subject to graduate students, clinicians, and researchers interested in the pathogenesis of malignant neoplasm. The author begins by sketching a historical account of how it took almost a century to appreciate the link between infectious agents and oncogenesis. This includes the seminal contributions of Peyton Rous, who demonstrated the cell-free transmission of chicken sarcoma in 1911, the description of a “milk factor” (later known as a mouse mammary tumor virus) by John J. Bittner in 1936, and the discovery of a specific childhood lymphoma by Dennis P. Burkitt in 1958 and its etiological agent, a herpes virus, by Michael Epstein, Yvonne M. Barr, and Bert G. Achong in 1964. The text is elegantly arranged, both by the agents and the type of cancer they cause. The author has devoted at least a small section to most known human viruses and discusses the current understanding of their link to cancers. While much of the focus of the book is on infectious agents and human cancers, animal models of cancers also are discussed. Treatment options, including preventive and therapeutic vaccination, appear at the end of each chapter for most viruses discussed. Each chapter has an extensive bibliography reflecting literature as current as 2006. While the author makes an effort to summarize key findings from current literature, the text sometimes suffers from lack of coherence as the author goes from aspects of cell biology to describing a specific step in a biochemical pathway to aspects of molecular biology in the same paragraph. Herpesviruses, papillomaviruses, and retroviruses are the three most important groups of infectious carcinogens, and these get additional attention in the text. Interestingly, in 2006, the U.S. Food and Drug Administration approved Gardasil®, a human papilloma virus vaccine. This vaccine protects against four human papillomavirus (HPV) types. HPV Types 16 and 18 cause 70 percent of cervical cancer cases, and HPV Types 6 and 11 cause 90 percent of genital warts cases (source: http://www.gardasil.com). Cancer is a significant cause of mortality in people infected with HIV, albeit indirectly through immunosuppression. However, the author intentionally does not treat this important group of retroviruses and refers the readers to relevant literature. Although tumor bacteriology or tumor parasitology did not become as well established as tumor virology, the book has an informative chapter contributed by James G. Fox, Timothy C. Wang, and Julie Parsonnet on Helicobacter infection and cancer. The authors focus on H.pylori — its discovery, life cycle, specificity, virulence determinants in cancer development, and cancer prevention. They also discuss animal models of Helicobacter-induced gastric cancers and virulence determinants of Enterohepatic Helicobacter spp. The penultimate chapter deals with parasites and human cancer. Although there are numerous sporadic reports linking parasites (especially Schistosoma trematodes) and cancer, the author concludes that this is still a gray area and one that remains poorly understood. In fact, the first positive reports on infectious cause of cancers linked parasites, liver flukes, and Schistosoma with specific human cancers. Ironically, the Danish scientist Johannes A.G. Fibiger won the Nobel Prize for Physiology or Medicine in 1926 for his investigations incriminating the nematode Ganglyonema neoplasticum in rat tumors, although his results have not been confirmed independently. Globalization, coupled with increases in human migration, means that more and more humans will be competing for space and resources with wild populations of animals that harbor infectious agents. Such encounters have the potential to result in hitherto unknown human diseases, including cancers. This book will serve as a useful reference in understanding some of these infectious agents and their role in development of cancer.