There's no answer for cancer

Watch out! Confusion and deception abound when it comes to treating cancer. No matter what anyone says, we don't yet have a cure — but why? 

 
Illustration by Kayla Oliver

Illustration by Kayla Oliver

 

Overt Analyser is a monthly column by Chloe Warren that reflects on her experiences as a twenty-something scientist. Chloe is a PhD student in medical genetics at the University of Newcastle and really thinks too much about most things.

Cancer is scary. It's scary for obvious reasons, but also because it's so complicated. Not only is it difficult to diagnose, treat and experience, but it is also difficult to describe. Cancer is not one disease, but a collective name for what can happen when our body's chemical instruction manual goes wrong.

Unfortunately, our society's collective fear of this mysterious illness makes us vulnerable, as a number of people and groups stand to benefit from our fear. Food companies can market products as being 'superfoods,' despite the term having no real meaning. Media outlets can publish poorly construed interpretations of scientific studies, gloating cure-alls and globally effective treatments with catchy headlines. Lifestyle gurus preach detoxifying juice cleanses and strict diet practises. Some cancer patients (real or fake) take it upon themselves to offer generic medical and nutritional advice to anyone who'll listen, despite their lack of qualifications. All of these mixed messages make cancer even scarier than it already is. 

I find it difficult to describe what cancer is without stepping back first. It's important to know that we are all made up of cells and that every cell contains DNA. DNA is the chemical instruction manual for the cell; it codes for proteins. Proteins have many different roles within the cell — structural proteins maintain the shape of the cell, transport proteins ferry important molecules across the cell, defensive proteins protect the body from infection, and so on. Proteins, in short, are integral to cell function. 

While a cancer remains benign (left), it can be removed using surgery or shrunk using radiation therapy. Once a cancer has metastasised however (right), cancer cells may be anywhere throughout the body and is therefore much more difficult to treat.

While a cancer remains benign (left), it can be removed using surgery or shrunk using radiation therapy. Once a cancer has metastasised however (right), cancer cells may be anywhere throughout the body and is therefore much more difficult to treat.

Sometimes the odd mistake in a cell's instruction manual goes unnoticed. Sometimes the mistake gets fixed. But sometimes a mistake (or, more likely, a collection of mistakes) can render the cell incapable of making the right proteins and therefore of doing its job properly. It may begin to replicate uncontrollably as it loses the ability to regulate its behaviours or respond to external signals telling it to slow down. This is how a tumour can form.

Some tumours, if caught early, can be removed surgically and the patient may never experience a recurrence. However, if tumour cells spread — via the blood vessels or the lymphatic system — it can be much harder to treat. You can't even see individual cancer cells, let alone surgically remove them. The whole body has to be treated — with chemotherapy — to make sure that the cancer cells are gone. Unfortunately, not all cancers respond to current treatments, and side effects can be extremely unpleasant. 

Mistakes in the DNA instruction manual can be inherited. For example, you might have heard about BRCA1 mutation (mutation being another word for 'mistake' in the context of DNA) being linked to breast and ovarian cancer. Sometimes the cancer isn't inherited, and mistakes just happen. Before a cell divides to generate two new daughter cells, that classic DNA double helix we know and love splits in two. Both strands are then copied so that each new cell has its very own double helix. 

A single cell will split in half (a process called mitosis), sharing half of its DNA with each daughter cell. A huge team of proteins then works to read and replicate the single strands of DNA in each new cell.

A single cell will split in half (a process called mitosis), sharing half of its DNA with each daughter cell. A huge team of proteins then works to read and replicate the single strands of DNA in each new cell.

There are 3 billion base pairs (letters in our instruction manual) of DNA in every cell, and we are made up of around 37 trillion cells. It's hard to estimate how often new cells are made — but we do know that we shed around 50 million skin cells every single day. That means that 8 trillion trillion (or 8x1017) bases of DNA are copied every single day in our skin cells alone. Cells do an amazing job of copying DNA and repairing errors — but nevertheless, mistakes do happen.

The longer we live, the more times our DNA has been replicated, and therefore the more likely it is to harbour mutations. In some ways, cancer is a rare but inevitable side effect of being alive. But there are key things we can do to reduce the frequency of these DNA mutations, and none of them are particularly surprising. 

In order to successfully replicate a DNA strand, proteins need to be able to read the DNA bases (or, in this representation, shapes. Triangles have to be paired with squares and circles have to be paired with pentagons). If the DNA is damaged, the proteins are unable to read the bases and may make a mistake.

In order to successfully replicate a DNA strand, proteins need to be able to read the DNA bases (or, in this representation, shapes. Triangles have to be paired with squares and circles have to be paired with pentagons). If the DNA is damaged, the proteins are unable to read the bases and may make a mistake.

Eating a balanced diet with plenty of fruit and veg, exercising regularly, practising sun safety, quitting smoking, reducing your alcohol intake and following appropriate screening guidelines are the best measures you can take to reduce your cancer risk. This is because chemicals in cigarette smoke and alcohol, and UV radiation from the sun, introduce physical changes in the structure of DNA molecules, making them more likely to be read incorrectly and/or for mutations to be introduced. Fruits and vegetables contain anti-cancer agents — but it's important to remember that no single vegetable is better than another (nope, not even kale), and that it's best to just eat a variety. 

So where do all these extra 'anti-cancer' messages come from?

Cancer is an extremely active area of research. There are hundreds of thousands of cancer researchers working to examine the causes of cancer, to improve the treatment of cancer, and to be able to predict cancer risk. Pharmaceutical companies are constantly developing new drugs and testing them in clinical trials. The US National Cancer Institute has an annual budget of around US$4.9bn. Every day there are scientific papers published along the theme of cancer research, and it's actually fairly rare that one will get picked up by the mainstream media or that anyone outside of academia will ever even know the research was done. Unfortunately, when they do get picked up by mainstream media, cancer research stories can become strangely warped. In a race to sell newspapers and direct Internet traffic, nuanced studies are reduced to blunt and punchy headlines: “Mushrooms beat cancer,” “Sunlight stops breast cancer” or “Pill to prevent breast cancer.” If you're looking to avoid misinformation, it's a pretty sound rule that if it sounds too good to be true, it probably is. 

It is highly unlikely that any new cancer prevention method more effective than those I have already mentioned is ever going to be found. And the only reason I say 'highly unlikely' as opposed to 'impossible' is because I'm a scientist and I don't do definites. Also, if anyone tells you there is one single thing you can do to prevent cancer, they're lying. All we can ever do is reduce our risk of developing cancer. (See? No definites.) 

Despite the mass of research, lung cancer was still the 3rd most common cause of death in high-income countries in 2012 (colorectal cancers came in 7th and breast cancer at 10th). So why haven't we 'found a cure?' There's not really any other way to put it, but: it's complicated. Remember those 3 billion base pairs of DNA and 37 trillion cells? Well, where the mistake/s occur in the DNA and which cells they occurred in determines what type of cancer will develop, and what treatment it will or won't respond to. And I'm not just talking about breast or lung or colon cancer — I'm talking about the cancer at the molecular level. This is why the prospect of personalised medicine is so exciting. Cancer treatments used to be given purely based on the cancer's location. These days, it's far more likely that a tumour specimen will be assessed at the molecular level in order to inform the clinical decision-making process. There will never be one single cure for cancer, because cancer is not one disease. 

Many compounds kill cancer cells in culture plates like these, but few have the properties required of useful drugs. Sanofi Pasteur/Flickr (CC BY-NC-ND 2.0)

Many compounds kill cancer cells in culture plates like these, but few have the properties required of useful drugs. Sanofi Pasteur/Flickr (CC BY-NC-ND 2.0)

So if you read about a drug, food or essential oil being hailed as the new 'cure for cancer,' it should ring alarm bells. It's true that there are new cancer-fighting drugs being developed all the time, but each drug is specific to a certain molecular subtype or group of subtypes. It's also worth noting that, for the most part, when foods are heralded in the media as having 'cancer-killing properties,' it's because components of that food have been found to be toxic to cancer cells in culture. As a molecular biologist with way too much experience in cell culture, I can promise you that there is an endless list of things that will kill cells in culture and none of them are usually worth celebrating.

Cell culture is the first rung on the ladder of developing a new treatment, and there are literally thousands of ways a treatment will get ditched as a potential cancer drug before it makes it to the clinic. How does it affect healthy cells? How will it get delivered to the cancerous sites? Is it safe to use on animals? Is it stable? If the answers to these questions aren't promising, the drug may never be used to treat real patients.

Unfortunately there are a lot of 'cancer survivor' bloggers who will post prolifically about how their non-fat gluten-free vegan diet cured their cancer. On the off chance that any of these stories are true, it's important to remember that these (questionable) stories are all anecdotal. This is in contrast to the veritable mountains of data that must be acquired before a drug can be approved for use to ensure it is safe and effective. 

It is true that we live in exciting times for medical research. In 2001, it cost US$100m to sequence an entire human genome. Today it's closer to US$1,000. As scientists and mathematicians work together to improve the ways we can make sense of these data, personalised medicines, including cancer treatments, are slowly becoming more diverse and widely available. Unfortunately, cancer isn't going anywhere fast, and it's going to take a lot more than kale to stop that. 

Edited by Jack Scanlan