Cancer is a twentieth-century disease. While it was not unknown before, it was in the twentieth century that it became such a dominant force, recognized as a leading cause of death and the focus of high-profile advocacy movements and a national research enterprise. By 2010, according to the International Agency for Research on Cancer, cancer will become the leading cause of death worldwide. Cancer in the twentieth century is a collection of twelve essays developed out of a conference held in 2004 at the National Institutes of Health in Bethesda, Maryland. The papers, which focus primarily on Britain and the United States, are loosely grouped into three areas—education and marketing around cancer, therapeutics, and prevention and risk. While they are distinct papers, using a variety of different historical approaches, some compelling common themes emerge. Indeed, an extensive introduction by David Cantor does an admirable job of synthesizing the various papers. Specifically, Cantor emphasizes the diversity of definitions and approaches to cancer control and cancer prevention that appear throughout the century. While early intervention was a consistent theme, opinions have diverged over where exactly to place the locus of intervention. Cantor states that the concept of cancer prevention is as old as cancer itself, but that what has changed is where prevention proponents target their efforts. For much of the century, American and British cancer prevention efforts were dominated by a focus on “early detection and treatment”. But in the 1960s and 1970s cancer prevention was “reinvented” with an emphasis on lifestyle and environmental causes of cancer, such as cigarette smoking and chemical exposures. Since then, we have seen an ongoing tug of war between these two different approaches to prevention, as they fight for a limited share of public attention, political support and financial resources. The first group of papers highlights the diversity of methods of communicating information about cancer and ways in which it is portrayed to the public. While the focus on early detection and treatment might appear to be a simple matter of education and raising awareness, these papers illustrate how public perceptions of cancer have been shaped throughout the century by the interests of advocacy groups and Hollywood movie producers. For example, Gretchen Krueger explains that while “poster children” were used to convey messages about treatment of childhood cancers, they were also intended to elicit emotional responses and financial support from viewers. While substantial progress has been made in the treatment of various cancers, papers in the other two sections of the book remind us that cancer therapy remains highly contested. At the same time, new technologies and concepts of risk have expanded the boundaries of the disease, turning otherwise healthy individuals into cancer patients. Papers by John Pickstone, and Peter Keating and Alberto Cambrosio demonstrate that, even in our age of evidence-based medicine, the methods in use by scientists and clinicians to evaluate therapies and make decisions are profoundly influenced by ad hoc historical factors. And Barron Lerner's account of Rose Kushner's dual role as patient and advocate illustrates how the challenges faced by cancer patients have altered the traditional roles of doctor and patient and created new conflicts. However, there is a central issue lurking here that unfortunately is not directly addressed by any of the papers—that is, how the growing role of science in the clinic has blurred the distinction between research and treatment. An enormous enterprise developed around cancer research in the twentieth century, and the rapid pace of research means that today novel therapies can make news before they have been approved for the market. How has the increasing authority of the scientific expert changed the ways in which patients and physicians interact? How is the line between research and treatment drawn in the case of cancer patients undergoing experimental therapies? There are some additional gaps in addressing such a broad topic. For example, it would be useful to have comparisons with countries other than the US and Britain. Yet overall, this collection of essays provides a number of compelling and novel observations on cancer in the twentieth century, and hopefully it will serve to inspire further scholarship in this area.