A close family member of mine, with terminal cancer , recently stopped chemo after 3 years because it created more problems than solving them eg blood problems, heart problems etc.
How does chemotherapy actually work? What is the aim of it?
In: Biology
First off: I’m really sorry to hear that. That has to be an awful situation for you and your family, and I want to express my sympathies there.
As for your question, I actually worked in a lab for possible chemotherapeutic drug candidates for a bit, so this is something I have at least some knowledge about (also a degree in biomedical science). Though to properly explain chemotherapeutic drugs, I need to give a little context:
Cancer is a mess because it’s a very wide group of conditions with common themes. See, most cancers can be summed up as a disruption of your normal cells’ self-regulation. Every cell has a very complex and interconnected system of pathways that allow it to carry out their normal functions. They also have pathways to deal with damage–either by repairing themselves if the damage is manageable, or killing themselves in a controlled way as to not risk greater health hazards. A sort of flag of “I am too damaged to be safe to keep living, and I must be removed”.
Cancer arises out of *multiple* things going wrong at the same time. The cell is dysregulated and damaged, but *doesn’t* flag itself for this controlled death. It also doesn’t flag for *other* cells to do this. It essentially just… continues on in its damaged state, where it can accumulate other mutations while continuing past the point where it would normally be pruned. Cancer then involves (mutational) activation of growth pathways, so this cell instead starts to *replicate* itself, damage/mutations and all. This ramps up further and further in stages of accumulating mutations until these uncontrolled cells invade surrounding tissue, interfere with vital processes, push on vital organs/tissues/etc, absorb necessary nutrients, and so on.
Now, when dealing with this, cancer has an unfortunate advantage over many other diseases: they look just like your own cells. Your body is always attempting to clear out disease and aberrant cells that could be pre-cancerous, but at a certain point, they successfully pass as “normal” despite not being so, or otherwise escape being culled. And, you can’t just blindly target them because you would essentially just be destroying normal tissue–instead, you try to exploit the ways they are different from normal cells for treatment. After all, if *everything* was normal, they wouldn’t be cancerous.
This depends on the cell type, but this is where therapeutics come in. In the case of chemotherapy, you’re looking at poisons that effect cancer cells *more* than non-cancer cells. Often one of the core criteria of cancer cells is that they reproduce *very quickly*, take in nutrients more than more cells to feed that division, and often rely on *one* pathway they have their runaway mutations in. So, chemotheraputic drugs might be poisons that *mostly* effect dividing cells (like cancer cells, hair cells, bonemarrow,…), might be inhibitors for specific growth pathways that are disruptive for normal cells but tolerable (but not for these cancerous cells), and so on. Unfortunately, this is generally a case of hitting everything in your body, but hopefully hitting cancer *more*, then giving someone time to recover, and repeating the process, maybe with mixing other forms of treatment in.
Chemotherapy is basically killing cells in the body. It is literally poison. There are some more complexity to this, targeting specific types of cells, targeting cells that use more energy, cells that multiply, etc. But essentially chemotherapy will kill both cancer cells and healthy cells. The problem with cancer is that the cancer cells are actually regular cells with the same genes and structure as healthy cells. They are not different from healthy cells in other but one critical thing. So it is very hard to kill only the cancer. What we do to treat cancer, and this is true for both chemotherapy, radiation and surgery, is to kill a lot of cells, both healthy and cancerous, hoping that we are able to kill all the cancerous cells and only some of the healthy cells. The issue is that killing a bunch of healthy cells does create a lot of symptoms. Often these symptoms can be worse then the symptoms from the cancer and can even be fatal.
In simple terms, the goal is to poison the cancer to death before the rest of the body dies.
This is possible because cancer reproduces very fast. Faster than almost all of your healthy cells. That extra metabolic activity makes them the most vulnerable to the poisons that are used in chemotherapy.
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