Is cancer man-made?

A recent scientific study concluded that of hundreds of examined Egyptian mummies, the vast majority had no sign of cancerous conditions. Such conditions have, in more recent times, steadily grown so that they now end up afflicting about one third of Americans and a similar number of people in England, as well as comparable numbers of folks from other industrialised nations. The conclusion drawn from this inquiry was that modern cancer rates must be reflective of some circumstances of the modern world.

The study has no dearth of critics arguing that the mummies were probably from people who died too young to have developed cancer -- and yet, the researchers noted that the mummies did show other age-related disease indicators, like hardened arteries and osteoporosis.

View from a step back:

Let us step back, then, and ask ourselves why this might have come about, and what if anything we may do about it. Cells divide constantly, as the unimaginably tiny molecular machines called organelles, living in respectable numbers within the cells themselves, read the DNA encoded at the cell nucleus and using the molecular raw materials derived mostly from what we eat to construct copies based on that blueprint -- copies including a copy of the blueprint itself, a replicated strand of DNA. But there are copying errors from time to time, though mostly harmless. This is, veritably, the precise function that leads to sometimes-evolutionary change when such copying errors occur in combination with reproduction of the entire animal, and not just in its mundane bodily cells.

But there are occasions wherein a particular bad sort of copying error in cell reproduction leads to the cell becoming malignant, unable to serve its normal function and harmful to the body which contains it. And those cells continue to divide, and divide, and divide, and the DNA errors contained within them propagate and are even transferred to other cells, different kinds of cells, allowing some cancers to spread throughout the body and destroy the various systems which the body depends upon for its very survival!!

The pollution/cancer connection:

Which brings us to carcinogens -- substances found in our environment which, for whatever reason, attack our DNA's self replicating capacity and make it vastly more likely that this process will go awry with the most devastating and deadly results. Another moment's reflection of evolutionary biology is appropriate here: those who deny evolution by natural selection may ignore this message, even at the massive cost of human life that is the price of such ignorance. But for the rest of you, you know the human body (like all modern life forms) is the product of billions of years of evolution occurring in tune with the environment which we are adapted to thrive within, and millions of years of that process just within the vaguely human antecedents which gave rise to us. Nature could not know, nor could it foresee, that eventually we would introduce strange new substances into our surroundings, chemical amalgams which evolution could have in no way prepared our must fundamental structures to cope with.

Whatever the evidence of the mummies is taken to mean, it may hardly be straightfacedly denied that it is our pollution of the world which may be spawning our self-destruction, inflicting an ever-expanding proportion of cancerous circumstances upon mankind. Consider our unnatural exposure to gasoline and the fumes of its combustion; our strange dependence on plastics and their unnatural formulation; our interposition into the foods we eat of all manner of chemically concocted preservatives and additives and stuffers and fillers. I don't mean to exploit emotions, but I wish to emphasise the seriousness of this in pointing out that one of our beloved contributors here is fighting cancer. We all know someone in our larger circle of family or friends who has cancer, or has had cancer, maybe beat it, maybe died from it, or who will have cancer. If we are unable to face up to the truth of this horror, we will all eventually die from cancer, and our children will die from cancer, and coming generations of the human race will shrivel into the dust in the face of it. The only surprise here is that it took some scientists this long to point out what ought to be obvious in this age. It's time to really ask the question. It's time to do something about it.

This article is the Daily Mail's take on this perspective piece in Nature Reviews Cancer. The latter is not in the public domain but should be freely available if you have access via an academic institution or large library. Perspective pieces are not subject to the same kind of scrutiny as research articles and offer a space for opinion, reflection and the airing of controversy. The authors are palaeopathologists with, as far as I can ascertain from PubMed, no publication record in epidemiology or cancer biology.

The perspective piece presents an overview of studies on mummified Egyptian remains, claiming « a scarcity of cancer in the earliest remains » reflects a low incidence of cancer in the sample population. As the authors are doubtless aware, absence of evidence is not evidence of absence. Accurate epidemiological data are difficult to obtain in the best of circumstances. Analysis of a limited number of poorly preserved ancient specimens is unlikely to furnish it. Further, mummification was an expensive and time-consuming process – one not all of ancient Egypt's decedents would have been subject to, depending on factors including income, status, ethno-cultural group and religious belief. Mummified specimens are unlikely then to provide a randomised cross-sectional sample required for plausible epidemiological claims. As the authors admit, « other possible factors to explain this lack of evidence include the limitations of the diagnostic methods used by early investigators to study these remains, and the insufficiency of data to provide a reliable rate of cancer incidence. » The fact that the authors offer no quantitative data for their epidemiological assertions renders them difficult to seriously assess.

The authors seek further evidence of the ancient scarcity of cancer through literature, claiming « limited evidence » that ancient Egyptian physicians accurately diagnosed cancer. Even if this is true (in fact not uncontroversial), from the fragmentary medical papyri available, this does not constitute evidence that cancer was rare in antiquity. The authors admit that in ancient Greek medical texts, tumours were « common enough to be widely studied and recorded  », claiming this may reflect an increase in incidence or diagnosis. On the supplied evidence, these conclusions are tenuous.

The article goes on to argue that lifespan does not adequately explain the (claimed) lower incidence of cancer in ancient Egypt as mummies show evidence of other age-related conditions such as atherosclerosis, Paget's disease and arthritis. It should be noted that these conditions - particularly arthritis, which is almost a uniform age-related finding - have a much higher rate of incidence than cancers and so are much more likely to be present in analysed remains.

There is excellent evidence to demonstrate that environmental factors – some of which are anthropogenic - such as exposure to ionising radiation and certain chemical agents increase gene mutation and cancer incidence. This speculative article is bad science and does not constitute such evidence.