Meditations of an oncology geek

Why are cancer rates rising?

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Short answer: compared to ancient times, people are living longer and/or not dying of other causes.

The last century has seen a rise in cancer deaths, which has garnered increased media attention and general awareness. Although I am thoroughly pleased about increased cancer awareness, the barrage of information has lead a popular tide to believe that cancer is a contemporary disease, something innately industrial and unnatural. Though I do not wish to paint cancer in a perversely favorable light, I feel I should dispel a few popular rumors about the disease.

The first thing to understand about cancer is that cancer is an age-related disease. The data showed to the left is from the National Cancer Institute SEER program which tracks cancer statistics. Data is represented as deaths per 10,000 in the U.S. from 2003-2007.

In passing conversations with friends, family, or friendly acquaintances I am often asked why the prevalence of cancer is on the rise. Curiously, I often watch how the popular media (and worse, popular marketing!) portrays cancer. Although the points I am about to make are by no means exclusive, I feel that they are often overlooked in our understanding of the disease. In addition to the reverberating effects of the cigarette boom of the mid-20th century and the increased prevalence of lung cancer, there are these factors to consider:

1) People are living longer. Rooted in 40 years of experimental results and observations, the great cancer researcher Judah Folkmann once estimated that adults develops cancer several times a day, and that with an extraordinarily great efficiency, the body is able to detect it and destroy it. However, the body is not perfect, and by the laws of probability, the more time passes, the greater chance a tumor can evade the body’s defenses. For many types of cancer, it can also take decades for a pre-cancerous cell to acquire the genetic mutations necessary to even be seen as a potential threat to the body’s surveillance systems. It is for these combined reasons that cancer generally affects an older demographic; the older you are, the greater your chance of developing cancer. Compared to a century before, the average life expectancy for Americans has seen a 30 year, or 60% increase!

2) People are not dying from other health conditions. This is partially tied to #1. In the developed world, the reaches of modern medicine and public policy have done a pretty good job at combating infectious diseases. Modern medicine has provided antibiotics and vaccines, and society has made these remedies readily available, and in some cases, mandatory. Polio, mumps, measles, and smallpox are all but dead diseases. Compared to a century ago, few people die from complications from bacterial infections. Those that might have perished from other complications are living longer, and will eventually develop cancer. In an odd sense, we as a society are victims of our own medical success.

3) Lastly, cancer has been around for a long time. Plato described a medical condition of a large, growing mass that, when removed, resembled a central mass with arms. It was for this reason that it was given the name “Cancer”. The growing mass resembled a crab. In what was an ancient combination of case-study and surgical instruction manual, a papyrus scroll from Egypt in 1600 BCE outlined two cases of a growing, spreading mass that was largely inoperable. The Middle Ages in Europe saw more detailed, illustrated surgical manuals for the removal of breast tumors.

Essentially, ever since man has possessed writing, he has documented cancer. And this is not exclusive to one civilization or one time period. Cancer has been around for a while.

Awareness about cancer is paramount to effective treatment. Cancer is a condition that often takes decades to manifest itself into its truly terrible form: metastasis, or when cancer begins to spread and seed itself through the body. It is extremely hard to treat metastatic cancer, and unfortunately it is at this stage that most realize they have it. Identifying the disease early is the best way to treat it. And nobody knows your own body like you do, therefore, individual knowledge about the disease is crucial to detection, treatment, and survival. Cancer awareness is good.

Although these informational bits on cancer are by no means exhaustive, I hope that these points will help to clarify reasons why cancer is on the rise. Make no mistake: lifestyle and diet still affect chances of developing cancer, and the last thing I would like to convey is a sense of determinism and fate. If anything, we should be pleased that we are more concerned about cancer than the host of other ailments that have plagued mankind for millions is years.

-Ryon

Edit: (22 February 2011) Prompted by a comment below, I felt that this article could be made better by including more statistics. The table above and description thereof were inserted. I also produced a graph of the data, but it’s not very pretty, so I decided to include it below. Cancer deaths per 10,000 in the U.S. from 2003-2007 are represented.

Written by Ryon

February 20th, 2011 at 3:45 pm

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2 Responses to 'Why are cancer rates rising?'

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  1. Another interesting theory well written… http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1693790/

    Erin

    22 Feb 11 at 2:05 pm

  2. Hi Erin,

    Thanks for the link to triage theory!

    By Ames’s hypothesis, Triage theory could contribute to the onset of cancer at younger ages in those that are malnourished (in terms of minerals and vitamins). Ames predicts that a high-calorie, low nutrient diet would contribute to cancer risk.

    The link between obesity (high calorie intake) and cancer becomes clearer and clearer every day, and it is now accepted by many cancer biologists that a high-calorie, low exercise diet can contribute to cancer risk. Though, equally robust studies into mineral deficiency and cancer have not yet been produced.

    On the flip side, epidemiological studies of people that have survived famines show shorter stature, lowered reproductive rate, and delayed onset of several age-related diseases, cancer being one of them.

    I will be very excited to see what results from in-vivo studies of triage theory as applied to cancer. If done in mice, these take years. If done in other mammalian model organisms, the studies take even longer. For all we know, these studies might already be underway!

    I will write more about cancer prevention, but the main focus of this article was to highlight the major reasons why cancer is so prevalent in society today: we are living longer (because we are not dying of other things), and cancer is an age-related disease.

    Age is the number one greatest risk factor for developing cancer. Greater than UV damage, greater than smoking, greater than anything that has been discovered so far. A morbidly obese, malnourished 20-year old will still have a much lower risk of developing cancer than a fit 90-year old with balanced nutrition.

    That contrast is true because of the same basic biological quirk that gives rise to Ames’s Triage theory: Evolution does not care about those that cannot reproduce. That’s why there are not strong selection pressures to live many decades after having kids. Whether a diet short in certain vitamins and minerals can contribute to accelerated cancer onset remains to be elucidated. That’s not to say it won’t.

    An example of shunted fitness is the fact that significant cancer onset does not begin to rise until after 30 years of age. From an evolutionary fitness standpoint, those are the prime years to reproduce, and the body will put a lot of resources into maintaining health. This is of great interest to some cancer researchers, because that data suggest that there might be cancer suppressing mechanisms in our body that are turned off (and might be able to be turned back on!)

    -Ryon

    edit: I had to check my statistics!

    Ryon

    22 Feb 11 at 2:59 pm

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