When it comes to naming the deadliest disease, most will immediately think of cancer which isn’t a bad guess as around 7- 9 million people die due to cancer globally (See Fig1.1)
and more than half a million come from the US alone, so it is our utmost priority to tell you more about this disease(s) and how far we have reached to find its cure. As most of our readers do have a vague idea about cancer and what it is, but to keep everybody on the same page, we’ll start by defining one of the deadliest diseases.
What is cancer?
The human body is a very complex machine, which needs to have control over all the tissues it possesses, and most of the time, it’s a fine ride and all the cells perform functions they’re supposed to. Unlike sponges, the human body has many organs that all need to synchronize to help the body live. Sometimes, cells manage to escape this and mutate, grow and divide, which slowly builds into a tumor. The tumor here may be a Benign tumor, which in most cases isn’t very critical (until it is pressing on any vial structure like blood vessels or nerves), as they don’t spread or it may be a cancerous tumor, which metastasizes (spread to other sites in the body by metastasis) which if not treated will almost always be fatal. Cancer can occur anywhere in the body because cells are found everywhere in the body. As these cells start to divide, they form their own tissue, which we call a tumor, and can spread to other places, therefore invading other organs, which destabilize them. When this happens, cancer becomes virtually impossible to stop as the disease reaches its most advanced stage. So, it is crucial that any abnormal developments in the body are recognized as soon as possible and the diagnosis be done in cancer’s infancy.
How does Cancer form and grow?
Every cell originates from a stem cell which is at the top of their hierarchy (See Fig 1.2).
When it divides, it creates a daughter cell just like itself and a more advanced cell than the parent stem cell. This process happens at a specific time of the cell’s life so that proper functions continue to happen. The stem cell then either differentiates after the division or have some mechanisms that kill the cell (that’s what lysosomes are for), but when these mechanisms fail to either eliminate the cell or the stem cell fails to differentiate, an organ ends up with too many cells, which may lead to cancer.
The mutations, which cancer cells undergo.
With the image above, made by R. Goninan, we will explore how cancer cells mutate from a normal cell and form different types of ‘subtypes’ of their own, but first, we should know how a stem cell (or any other cell) mutates or fails to differentiate or die (either the latter or the former). These can happen either when you inherit the cancer genes from your parents, which according to Dr. Harnold Varmus happens at quite a reasonable frequency when it comes to low-risk genes, however sometimes genes with a high risk of cancer do get inherited (example: BRCA-1, BRCA-2), they affect the tumor suppresser genes (tumor suppressor genes protect the body against cancer) because they affect the accurate copy at which the cells reproduce and repair DNA, which may make an individual liable to cancer.
Various factors behind someone getting Cancer
The other factor may be environmental influences, like a high exposure to UV rays of the sun (don’t worry, tanning for some time once a while won’t do you any harm) or exposure to a radioactive background.
Another factor might be smoking too many cigarettes, which may cause cells in the lungs to mutate and end up becoming cancer.
The third cause is a ‘mistake’ in DNA replication when a cell divides into 2 daughter cells, the DNA in the cells has to be replicated too, and watching the pace at which this happens, mistakes become inevitable, and to correct those, but with a probability of about once in a billion, mistakes are left uncorrected, which can also be a reason for cancer.
Changes in mutations
With context to Dr. Harnold, the most envisioned changes are a change in which the nucleotide in the DNA, is a position in a region of DNA that encodes for protein. The proteins are made up of amino acids; there are about 20 amino acids placed in proteins and every triplet of nucleotides and DNA encodes a single amino acid.
As of figure 1.6, the highlighted box shows that GGC changes to GTC, this changes the kind of amino acids found in that location. The change given in figure 1.6 is the most commonly encountered change in most kinds of cancers. The other kinds of change may be when instead of the 23 pairs of chromosomes in humans, there are a different number of chromosomes present when a cancer cell divides. Now, back to figure 1.5, the normal cell here, has now mutated to form the ‘blue’ cancerous mutation, we’ll call it the founding clone, it then forms a tumor and keeps on dividing, and spreads all over the lung, the founding clone then mutates into other subtypes that are a little different than the founding clone, as the diagnosis is made, we can see that there are different subtypes and not all of the tumor is made up of the same cell. Peculiarly, after the treatment, all the ‘blue cells’ are gone, making the tumor shrink, but the treatment has no effect on the other subtype or has little effect on some and the surviving cells regrow and kick starts another set of mutations which later metastasizes and spreads elsewhere causing more subtypes to occur and making cancer unstoppable. Later, there is a resurgence of cancer and it metastasizes and forms tumors elsewhere, in the bone, the liver, and the brain. A closer look will show you that there is a different ‘type’ of the same cancer in every tumor, making it even tougher to get a treatment that’ll work for all the subtypes of cancer.
Is there any cure for cancer?
While there certainly isn’t any medicine that miraculously cures all types of cancer knowing how hard it is to make a cure of even a single type of the disease, breakthroughs have certainly been made. Here are some examples:
Leukemia: In almost every case of Leukemia, there is a formation of a specific gene (fig1.7), that creates an enzyme that has an uncontrolled activity that is responsible which gives this gene to divide in an uncontrolled way, thus creating this Leukemia. So, what good is this? The remarkable thing is that there is an ‘almost’ cure for this. When this molecule was discovered, it appeared to have blocked the enzyme, and most of the cancer cells died. The molecule discovered was harmless and has now been approved. The patients now have a fully recovered life expectancy and if the drug’s consumed as prescribed by doctors, the chances of remission are virtually null. Here’s an example of the improvement. (Fig 1.9)
Lung Cancer- unlike Leukemia there are precession drugs though are effective but become ineffective after some time due to drug resistance of cancer. The next figure, (Fig 1.10) shows the number of mutations, every short colored dash here means a different mutation for a different gene. Now, as we have emphasized, that every cancer is different, and Fig 1.10 is clearly proof of that. Meanwhile, there is an ‘almost’ cure for lung cancer too, that is: Quit Smoking and chewing tobacco, almost a million deaths occur per year globally due to lung cancer and the number will drop significantly over the next few years.
Rest of Cancers- Precision drugs are becoming better over the years and the lethality of cancer is decreasing, but there are a few different methods where the cancer cell (or tumor) isn’t directly attacked but its resources are altered. All cancers, though diverse share the same traits (mentioned in Fig 1.11, please care to read them). Some ways may be blocking their access to blood vessels, inhibiting their DNA growth, etc. Other ways include using the immune system against the cancer cells, preventing cancer from doing lethal damage to the body (Immunotherapy), etc., however, the techniques commonly in use are surgery, where the tumor is removed directly from the body before it metastasizes, Chemotherapy, where drugs are introduced in the body to prevent the growth of cancer and kill it and Radiation therapy, etc. (Bone marrow transplant, Hormone therapy, Targeted drug therapy, Cry ablation are currently in use too). When somebody is diagnosed with cancer, the name of the disease can itself crush the morale of a person even before cancer has done any damage, so it is important to keep our faith in our doctors who will work to try to keep you alive.
Author: Anurag Mandal
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