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Cancer: What Scientists Know Vs. What the Public Believes

Cancer occurs when cells begin to divide uncontrollably. We can minimize the chances of this occurring but, first, we must disentangle real risk factors from imaginary ones.

Horror writer H.P. Lovecraft wrote in Supernatural Horror in Literature that “the oldest and strongest emotion of mankind is fear, and the oldest and strongest kind of fear is fear of the unknown”. I would argue that nowhere is this more visible in modern medicine than where the “C” word is uttered.


This simple word seems to have a paradoxical effect on most people. On the one hand, it evokes very concrete images and brings to mind the facts we know about the procedures and treatments associated with this disease. The word is potent and we seem to have a clear idea of what it means to be dealing with it. On the other hand, the word carries with it an aura of unease, a certain shapelessness, as if its identity is hazy and out of focus. While many people understand what “cancer” means practically, very few understand what cancer actually is.

Cancer is this “thing” you have inside of you. Cancer grows. Cancer spreads. It is an unwelcome invader against which one must militarize. We go after it. We fight it. Some fall on the battlefield, while others conquer it. Far from being a clear enemy, however, cancer seems permanently shrouded in darkness. Time to turn on the light.

Cancer is the corruption of a natural process

Cancer is not some ectoplasm that possesses one’s body overnight, nor is it a poison slowly seeping through our organs; cancer is the corruption of a natural process. When the cells of our body start to divide uncontrollably, this is what we call cancer.

The material that constitutes our body is organized in a hierarchy, much like paragraphs are made out of sentences, which are made out of words, which themselves are formed by letters. At the top, we have “organ systems”, like the nervous system, which is composed of different organs, like the brain, working together to perform a specific function. The organs themselves are made up of different “tissues”, which are collections of similar cells. Hence, organ systems are made up of various organs, each of which are made up of various tissues, each tissue being made up of a type of cell. At the bottom of this hierarchy lies the basic unit of structure and function of all living organisms, a cell.

Cells come in different shapes, all adapted to the part of the body where they reside: they are the basic building blocks of life.

For tissue to grow, its cells need to divide. When a cell splits into daughter cells, it first copies the entire content of its DNA (known as the genome) and subsequently sequesters each half of its content to opposite poles of the cell, like a perfectly fair divorce. The cell then splits into two. A simple process, it would seem, but one which must be tightly regulated.

Like driving a car

The division of a cell is controlled by two main groups of agents: “accelerators” and “brake pedals”. Molecules that perform an “accelerator” function drive cell division, whereas those that act as “break pedals” put a stop to it. There naturally exists a balance between these two, so that cells divide at just the right pace. What invariably happens in cancer is that “break pedals” are knocked out and heavy stones are thrown on “accelerators”. The net result is that cells grow, and grow, and grow, resulting in a mass of cells that should not be there: a tumour, also known in medical terms as a “neoplasm”.

Not all tumours are cancerous, however. Benign tumours are masses of dividing cells which lack the ability to invade their neighbour. These tumours are like countries which have a small militia and could not survive the military might of their neighbour, so they do not go to war. The main property of cancer is its ability to invade, to break free of its crib and travel to distant parts of the body using either blood or lymph. Benign tumours lack this property and are thus much less troublesome. In fact, benign tumours are quite common: skin moles are a good example. Thus, it is the so-called malignancy of a tumour—its ability to invade and worsen the condition of the patient—that determines if it is cancerous or not.

What causes cancer… versus what we think causes cancer

A minority of cancers are partly due to a genetic defect you inherited from one of your parents. It’s a little bit like buying a car that already has an unreliable break pedal. You’re at an increased risk of getting into an accident.

Besides these inherited errors in your genetic code, there are well-established risk factors for developing cancer, many of which can be decreased if not eliminated by changing our behaviour. But are we aware of that these factors put us at risk of developing cancer? And can we tell the right factors apart from fake ones?

A recent survey reveals that, at least in the representative English population used, this knowledge is not a given. Only 30% of respondents correctly reported that infection with the HPV virus and low consumption of fruit and vegetable were known risk factors for cancer. Meanwhile, almost half of respondents thought that stress and food additives give you cancer (they don’t, though the jury is still out on nitrites), while over a third said that genetically engineered food is a risk factor (it’s not).

(The full list of science-based risk factors for cancer used in the survey was active smoking, passive smoking, any alcohol consumption, any red/processed meat consumption, being overweight, sunburnt more than once as a child, being aged 70 years or older, having a relative with cancer, having an infection with HPV, and low physical activity. Obviously, they are not all equal in their risk for causing cancer.)

The authors of the survey point out that obesity was not well recognized as a cancer risk factor in their data set: only about 60% of responders correctly identified it. They go on to write that it is “the second leading preventable cause of cancer.” Of course, when major ads linking obesity to cancer go up, accusations of body shaming explode on social media. And when it comes to correcting misinformation on so-called GMOs, we science communicators already face a Sisyphean task, as mountains of fear mongering pseudoscience already exist linking GMOs to cancer.

Knowledge is often the cure to fear

In summary, cancer is the out-of-control division of a certain group of cells in the body, producing a tumour with the potential to invade neighbouring regions and far-away organs. Far from being a shrouded boogeyman of unknown origin, it is the dysregulation of a process scientists and physicians are understanding better and better every year. Our knowledge pushes back the boundaries of the unknown, until its accompanying fear takes up less and less room in our mind. The more we know about cancer, the better armed we become and the more rational we can be in facing this despicable disease.