Cancer, The Evolutionary Legacy (review)

Cancer, the Evolutionary Legacy, by Mel Greaves. Oxford, U.K.: Oxford University Press, 2000. 276 pp. $27.50 (hardback).

Approximately one in three of us will be directly affected by cancer during our lives, and virtually all of us will have friends and relatives who slowly succumb to some form of the disease. I personally have vivid memories of my grandfather straining for breath with an oxygen cylinder and a packet of Embassy Reds by his bedside. Writing a "popular" science book on the subject of cancer is, therefore, a tall order. However, I am pleased to say that Mel Greaves has achieved just that. Furthermore, he has done it with style, wit, and an engaging narrative style that does not compromise the scientific accuracy of the text. The confident and personal writing style, rich in historical anecdote, is a major strength and is ideal for the target audience, which appears to be anyone with an interest in cancer. Having said that, the real novelty of this book lies in the Darwinian framework used to present the historical, clinical, and epidemiological aspects of the disease. It is this framework that will also make the book appeal to professionals directly involved in cancer research, along with the ample notes directing the interested reader to reviews and primary literature.

The thesis of the book is straightforward and unifying: cancer is best understood from an evolutionary viewpoint. This perspective is not new, but it is synthesized for the first time here, and brings genuine insight and clarity to the subject material. The questions the author asks are simple: Why do we get cancer at all? How does cancer develop? Why are different races (or geographical regions) prone to different types of the disease?

To answer these questions, the main evolutionary concepts are introduced in the first few chapters and then expanded and elaborated upon as and when the time is right. The first is that our developmental and regenerative processes that have evolved over millennia involve cellular proliferation as a default setting; cancer is merely the unfortunate consequence of errors within these highly evolved and biologically vital systems. This is most clearly illustrated in the chapter on breast/ovarian cancer, which highlights the price paid by women for their modern lifestyle. More specifically, a reduced number of pregnancies and less time spent breast-feeding greatly increase the number of menstrual cycles, each of which involves cellular proliferation and an element of risk. However, men do not necessarily get off lightly. Ejaculation also leads to tissue regeneration within the prostate gland, and, in one of the more speculative chapters, the author suggests that this cellular proliferation may over decades alter the risk of prostate cancer. As always, if it feels good, it is bad for you.

The second and central evolutionary concept is that cancer occurs through a series of genetic changes that originate by mutation, but which persist and spread within the tumor as a result of a series of selection pressures induced by the physical and chemical barriers to clonal expansion. The complex progression through numerous selective bottlenecks (e.g., escaping cell death through mutation in p53, renewed growth following angiogenesis, surviving therapeutic intervention through drug resistance) to full-blown metastatic disease are clearly outlined.

The last major evolutionary concept is that the shifting tides of cultural evolution play a key role in determining cancer risk in human populations. The many variations upon this theme provide what I found to be the richest and most enjoyable sections of the book. These deal with the complex historical, social, and political factors that influence specific cancers including lung cancer (smoking), colon cancer (diet), and so-called "industrial" cancers. In these chapters, the attention to detail is particularly rewarding, with the inclusion of numerous instructive historical asides. For instance, although British chimney sweeps were prone to testicular cancer, German and Dutch sweeps were not for the simple reason that they wore adequate protective clothing and washed daily. Likewise, worldwide smoking...