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Asked by anon-220741 on 14 Jun 2019.
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David Wilson answered on 14 Jun 2019:
Cancer is a disease in which cells, almost anywhere in the body, begin to divide uncontrollably. When the growth occurs in solid tissue such as an organ, muscle, or bone, it’s called a tumour.
It’s important to say that not all cancers kill you. Overall, more than 50% of people diagnosed with cancer live for more than 5 years. Some cancers have survival rates of more than 90%.
Sometimes just the physical presence of the tumour itself is the biggest problem a big tumour can prevent the organ from functioning normally and can even cause death, this might happen in the heart or brain. More often, what ends up killing the cancer patient is what’s known as metastasis. This is when cells from a tumour separate from it, find their way into the lymph system or the bloodstream, and spread throughout the body. Each metastatic cell begins dividing and forming a new tumour in its new location. Our bodies usually can’t support the growth of that many tumours, and the tumours can disrupt the normal function of the organs they’re growing in. If that happens, and if the disease is left untreated, the outcome for the patient is poor.
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Kaitlin Wade answered on 15 Jun 2019:
David’s answered that really well. Not all cancers kill us though. Despite there not being a “cure”, there are many active treatments that do help prognosis. But, as David days, if the cancer becomes metastatic, that can be an issue.
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Nina Rzechorzek answered on 15 Jun 2019: last edited 15 Jun 2019 7:53 pm
There is a wealth of information about all types of cancer here:
https://www.cancerresearchuk.orgThe cancers I know most about are the ones affecting the brain and other parts of the nervous system. The brain and spinal cord are special cases when it comes to tumours because even ‘benign’ tumours (i.e. ones that do not invade into surrounding tissues or spread to other parts of the body) are considered ‘malignant’ because their growth and expansion can have very serious consequences and even be life threatening if left untreated. This is simply because the brain and spinal cord are enclosed in hard bony structures (skull and vertebral column) which means there is little space for extra tissue. If a tumour grows within the skull cavity (inside the brain or on the surface of the brain), over time this will lead to a build-up of pressure (known as raised ‘intracranial pressure’ or ICP which is very dangerous). This will effectively squash parts of the brain (leading to neurological deficits through pressure on specific structures, or by reducing blood supply to the brain). If not treated, the tumour will continue to grow and ultimately the pressure can become so great that an important part of the brain that is vital for life (the brainstem) is pushed towards a little hole in the back of the skull (known as the foramen magnum). The brainstem is essential for basic functions such as breathing and consciousness. Patients will generally deteriorate into a coma and then stop breathing.
Some brain tumours grow very slowly, and if they can be reached surgically they can be removed. The removal of a small benign tumour (such as a meningioma which develops from the tissue layers protecting the brain – the meninges) can achieve a long-term surgical cure. However some tumour types are not accessible by surgery or grow very quickly and spread throughout the brain in a more diffuse way such that surgery is unlikely to be of benefit (e.g. glioblastoma multiforme). Radiation therapy is another form of treatment that is sometimes applied after debulking surgery (to kill any residual tumour cells that cannot be seen by eye), or in cases where surgery is not an option. Together with chemotherapy, surgery and radiation therapy can extend life for a period, depending on the type of tumour, the stage and extent of disease.
The above has mainly referred to what we called ‘primary brain tumours’, i.e. those that start in the brain. However, there are several tumour types that can start elsewhere and then spread to the brain (e.g. lymphoma, various carcinomas) – we call these secondary or metastatic brain tumours. As above, these can ultimately lead to similar, life-threatening problems if ICP is raised.
Other types of cancer can affect the functioning of other essential organs (such as kidneys, lungs, heart, pancreas) or body systems (such as the immune system) leading to life threatening changes in blood pressure, respiratory function, key serum electrolytes (e.g. sodium, potassium), bodily fluid balance, or life-threatening infections. Some of these conditions or effects of cancer can be managed for a period of time though supportive drugs and other treatments. -
Kate Timms answered on 19 Jun 2019:
Cancer happens when a cell gets a mutation in its DNA, caused by something like smoking or radiation from the sun etc. If this mutation is in a gene which is involved in cells growing and splitting into more cells, then this can be the start of cancer. The cells can then grow uncontrollably from a single cell into a whole tumour.
At some point, some or all of the cells can acquire new mutations, which usually happen because of the cells dividing so quickly. These mutations can be in genes which make the cells stop doing the job they were originally supposed to do (we call this de-differentiation) or in genes which make them able to start moving about the body. This is what causes metastasis, the name we give it when cells move out of the original tumour and find new homes to make new tumours in the body.
They kill us because they stop our organs from working by overtaking them. -
Matthew Bareford answered on 21 Jun 2019: last edited 21 Jun 2019 8:58 am
To put it in the simplest terms:
Cancer is in essence an uncontrolled growth of cells. this is what forms tumours.
A growing tumour becomes a lump of cancer cells that can destroy the normal cells around the tumour and damage the body’s healthy tissue. This can make a person very sick.
If cancer cells spread around the body by travelling in the blood stream/lymph system, then they can form tumours in multiple locations around the body. this is know as metastasis.
So essentially if metastatic it will damage multiple locations, leading to damage of different organs and body systems/functions. In turn this damage will result in damage to other systems that will eventually lead to a persons death.
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