Cancer is a disease caused by a deviation in your own cells, not an external pathogen. Unlike normal cells, which divide through a cell cycle control system, cancer cells malfunction in this control system, causing them to proliferate uncontrollably, develop into tumours, and metastasise with devastating effects.

Cancer, a deviation in my cells

Cancer is a very common word in our daily lives, but it is still a disease that is associated with vague fears and dread. Despite the fact that research and information about cancer is steadily increasing, many people still don’t understand it. In particular, cancer comes in many forms, and the way it manifests itself depends on a person’s physical and genetic factors. Breast, lung, colorectal, and other types of cancer have different causes and pathways, but they all essentially start with an ‘aberration in the cells’. In this way, cancer is not simply a disease caused by external factors, but is related to very complex physiological processes that occur within the body itself.
The main character’s grandfather, who was diagnosed with terminal stomach cancer and eventually died after a long battle with cancer……. It’s a story we’ve all seen in dramas and films. Cancer is a very familiar word, but not a friendly one. The short word ‘cancer’ conveys sadness, fear, pain, and worry. As such, cancer has long been considered a terrible thing. In fact, according to the World Health Organisation (WHO), it’s one of the top 10 causes of death worldwide, so it’s definitely a scary disease. But where do these terrible cancer cells come from and how do they develop? If you’re thinking of pathogens like bacteria or viruses, you’re wrong. Cancer cells are the result of your own cells deviating from the normal cell cycle.

The cell cycle and cancer

The human body is made up of cells, the smallest unit of life. And cells replicate themselves as needed through a process called ‘cell division’. This process is called the cell cycle. When a cell completes one round of the cell cycle, it has finished dividing. Cell division is highly regulated and monitored in several ways because it is not only energy intensive, but it can also have a major impact on the surrounding tissues. Cells need external signals called ‘growth factors’ to divide, and even when they do, they can stop dividing at checkpoints in the cell’s state. Through this system of cell cycle regulation, the body not only prevents unnecessary cell division, but also effectively stops abnormal cells from proliferating.
The cell cycle is divided into G1, S, G2, and M phases. G1 is the phase in which cells prepare to divide, synthesising proteins and other cellular components as they grow. At this point, the cell decides whether it will continue or stop dividing, and then moves on to S phase, where DNA replication takes place. Then, in G2, the cell prepares for the final division, and finally, in M, the cell divides into two daughter cells. These processes must be precise, and if the cycle is not properly regulated, abnormal cell division can occur, leading to cancerous cells.

Key to the cell cycle regulation system: the p53 gene

One gene that plays a key role in preventing abnormal cell proliferation is called p53. It is so important that it has been called the ‘guardian angel of the genome.’ When a cell reaches the G1 phase of the cell cycle, the p53 gene decides if it can continue dividing. If the DNA in the cell is heavily damaged or otherwise deemed unsuitable for cell division, the p53 gene activates a protein called p21, which causes the cell to stop dividing. During this pause in the cell cycle, the cell can repair the damaged DNA with the help of several proteins, and once the problem is fixed, the cell can resume dividing. However, if the damage is too severe to repair, the p53 gene induces the cell to undergo apoptosis (cell suicide). The cell cycle regulatory system is a very important regulatory mechanism in the body that prevents the proliferation of abnormal cells that have accumulated mutations.

Tumour initiation

What happens when something goes wrong with this cell cycle control system? Cells divide spontaneously without external signals, and abnormal cells with damaged genes are able to proliferate unchecked. When this actually happens, it’s called a ‘tumour’. These abnormal cells can destroy organs and paralyse tissue function, as well as spread to other tissues, which is a serious problem. A tumour mass that has begun to grow uncontrollably can cause catastrophic damage to surrounding tissues, including rerouting blood vessels to get the nutrients and oxygen it needs to grow. This is why these tumours are called ‘cancer’ or ‘malignant tumours’.

The multi-step process of cancer

Cancer doesn’t happen all at once; it develops gradually through several stages. Initially, it’s simply a collection of abnormal cells with a slight failure in cell cycle regulation, but over time, mutations in the cells accumulate and eventually develop into a tumour. This process also allows the tumour to spread through the blood vessels to other parts of the body, a process known as metastasis. Metastasis is one of the main reasons why cancer becomes more deadly, and while it can be relatively easy to treat in the early stages when the cancer is localised, it becomes much more difficult to treat once it has spread.
Therefore, the difference between cancer cells and normal cells is whether the cell cycle control system is working properly or not. And at the heart of cell cycle malfunction is often a mutation in the p53 gene. In fact, mutations in the p53 gene are found in more than 50% of cancers. If you’ve been subconsciously thinking that diseases are only caused by pathogens that originate from ‘outside’ and not ‘within,’ this is your chance to dispel that notion. Remember that the direct cause of ‘cancer’, which takes the lives of so many people around the world, is not a virus or bacteria, but an aberration in your own cells.