Why Cancer is So Hard to Kill

0:06 well since it's totally normal to just have seven different bodies hanging out in a room here I figured we'd answer one of the most common questions that we get from students about the bodies that we have in our lab and that is what did they die from now it probably isn't going to be too shocking that most of the bodies that we have here died from some sort of condition or even multiple conditions but many of them actually died from cancer like this body died of coloral cancer this body died from breast cancer and this body died from lung cancer now what's interesting is that even though each of these bodies had a different form of cancer there was something that these cancers had in common that ultimately led to the death of each one of these bodies So today we're going to show you what this commonality was that led to the death of each of these bodies as well as many other people that have

0:52 unfortunately died of cancer we'll also talk about how cancer starts and discuss some very incredible built-in mechanisms that our bodies actually have to try to stop cancer from forming in the first place it's going to be a mutated one so let's do this so before we go back to the specific bodies in the lab and show you what ultimately led to their death let's start with understanding how cancer originates cancer is when abnormal cells grow out of control and this starts when the DNA inside the cell kind of goes off script the DNA contains the genes that essentially code for everything that the cell does including some extremely important mechanisms that are important to understanding cancer and that is when the cell should divide and when

1:40 necessary undergo apoptosis which is a form of controlled programmed cellular death and again these are tightly regulated processes but when mutations to certain genes occur this orderly process is disrupted and cells can start to divide out of control the genes that code for normal cell growth are called Proto onco but when they mutate they transform into enogen which are abnormally functioning genes that are capable of causing cancers and I'll mention these enco gen throughout the video so just remember oncogene equals bad mutated Gene that could lead to cancer and there have been many different enco that have been discovered in human cancers another Gene that is worth mentioning are anti-oncogenes also known as tumor suppressor genes which you could think

2:27 of as protective genes because as the name implies they suppress the activation of those cancer-causing enogen now here is something that is very interesting you have likely had mutant cells develop in your body so why haven't you developed cancer well only a minute fraction of cells that mutate ever lead to cancer and there are several reasons for this first most mutated cells don't have what it takes to survive they have less survival capabilities than normal cells and they simply just die off second the built-in controls remain intact only a few of the mutated cells that survive ever become cancerous because even most mutated cells retain their off switch or their normal feedback controls that prevent

3:13 excessive cell division for example maybe those anti- onco or those tumor suppressor genes are still working properly and stop out ofc control cell division third the immune system picture your white blood cells as Vigilant bodyguards patrolling your body for anything that looks out of place and most mutated cells look out of place because they expressed abnormal proteins due to their alter genes and when a white blood cell spots a mutant cell displaying these abnormal proteins this can trigger the formation of antibodies and other immune responses that result in the death of that mutated cell and the importance of our immune system with killing mutated cells is really put on display when we see that people taking immunosuppressants like after an organ transplant have an increased probability

3:59 of developing cancer by as much as five fold with certain types of cancers and lastly for cancer to form it usually requires more than one enogen to be activated at the same time and it often requires several for example one gene might get mutated that promotes rapid cell division but no cancer occurs because maybe another mutant Gene was not simultaneously present that coded for say like the development of new blood vessels that would be required to feed the growing cancer and so again it usually takes multiple mutated genes existing in that cell at the same time for cancer to start so the next question that you might have is what is the cause of mutated or altered genes well considering that trillions of new cells

4:45 are formed each year in humans a better question might be why all of us do not develop millions or billions of mutated cancer cells just through the sheer number of cell divisions that occur each year now we already discussed some of the mechanisms that our body has in order to deal with cells that do get mutated but even before that occurs our body works extremely hard to stop any Mutant genes from forming in the first place and this is because cells copy their DNA with Incredible Precision before the cell even divides plus after the DNA is copied there is a proofreading process that cuts and repairs any abnormal DNA strand and this also occurs before cell division is allowed to proceed yet despite these awesome cellular precautions probably

5:32 one newly formed cell in every few million still has significant mutant characteristics so in some cases chance alone is all that is required for mutations to take place and so some cancers are merely the results of bad luck however the probability of mutations can be significantly increased when a person is exposed to certain chemical physical or biological factors this includes ionizing radiation such as x-rays gamma rays particulate radiation from Radio active substances and even ultraviolet light all of these can predispose individuals to cancer because the radiation can rupture DNA strands and lead to many mutations you've likely also heard of carcinogens which are chemical substances that cause mutations and as an example the carcinogens that

6:18 currently cause the greatest number of deaths are those found in cigarette smoke these carcinogens cause about one quarter of all cancer deaths physical irritance can also lead to cancer which would be repeated physical damage to tissue isues like chronic abrasions in the gut can force cells to divide rapidly in order to repair the injury and the faster the division the greater the risk of Errors certain viruses can lead to cancer and this is because the virus can insert its own genetic information into one of the cells chromosomes which would obviously lead to a mutation of the original cell's DNA and of course genetics plays a significant role in your cancer risk for example in families that are particularly predisposed to cancer it is presumed that one or more cancerous genes are already mutated in the

7:05 inherited Offspring therefore a fewer number of additional mutations are required for those family members to develop cancer so if a cell or group of cells accumulate enough mutations for cancer to start why are these cells so dangerous well we have already mentioned multiple times that cancer cells grow and divide out of control and when enough cells divide they will form a mass called a tumor now this tumor can compress and potentially damage other structures which can lead to pain and loss of function of those compressed or damaged structures and you may have likely heard of tumors being classified as benign or malignant benign tumors tend to be encapsulated which means it is less likely for those cells that make up that benign tumor to break away and spread to a different site but that doesn't mean a benign tumor can't still cause some problems if you have a benign

7:52 tumor forming in the brain the brain is house within a skull which doesn't allow for expansion the brain can then get compressed which will obviously lead to some major problems but even still malignant tumors are much more serious because these tumors are not encapsulated which leads us to another reason why cancer cells are so dangerous and that is when they spread cancer cells especially those forming malignant tumors tend to have additional mutations that cause the cells to lose their properties of adhesion often healthy cells tend to adhere very well to their surrounding structures but cancer cells can lose these properties making them much more likely to break away and enter the bloodstream or the lymphatic system and now they could virtually go anywhere in the human body and start to grow at a

8:39 different sight and spreading of cancer to a new site is known as metastasis and once the cancer cells get to that new site many cancers have mutations that cause the cancer cells to release angiogenic factors that cause many new blood vessels to grow into the cancer thereby supplying the cancer cells with nutrients that supports their growth and all of this finally brings us back to the bodies that we have here in the lab this body didn't actually die of the col rectal cancer that was found in the colon and the rectum this body died when those cancer cells moved from the colon and the rectum to the liver to a much more vital organ this body didn't die from the breast cancer in the tumors that were found in the breast tissue but rather when those cancer cells moved

9:26 from the breast and into the brain this last body didn't just die from the lung cancer but when those cancer cells again move to multiple sites so this is what I meant by the commonality that leads to death with most cancers there are not very many cancers that lead to death without spreading there are a few that can kill without spreading like brain or primary liver cancer but again most cancer deaths are usually a result of the cancer spreading or metastasizing to a secondary site or organ that is much more vital to survival each one of these bodies could have potentially survived if they caught the cancer before it spread we can remove segments of the digestive tract we can perform mass ectomies and we can even remove segments

10:11 of the lung but this is why annual physicals and following recommended cancer screening guidelines can be so beneficial because the earlier you can detect cancer the better chance of survival also there is one last characteristic of cancer cells that I want to mention that also leads to their damaging effects but this is also a characteristic that is a target for a certain treatment cancer cells are kind of the greedy little Hogs of the party they are extremely metabolically active as they are constantly dividing so they compete with the healthy cells for nutrients and they often win so as a result normal cells can gradually die due to the lack of nutrients but because the cancer cells tend to hog all the nutrients this is one of the mechanisms of how chemotherapy works these are drugs that essentially target fast

10:57 dividing metabolically active cells and so the idea is that the cancer cell will take up more of the drugs leading to their death and the chemo does do a pretty good job of killing cancer cells but it also often kills other healthy cells that tend to naturally divide quickly such as skin and hair cells and even cells lining the digestive tract which is what accounts for many of the side effects of chemotherapy plus there are other toxicity issues that you have to deal with depending on the cancer and the drug and many people who have undergone chemo can attest to how difficult this treatment strategy can be but this is the major conundrum of cancer treatment even though cancer cells are different from our normal cells they still do maintain many similarities to our normal healthy cells so with so many different Cancers and potential mutations how do you design a

11:44 drug that could Target a specific cancer cell yet completely spare one of our healthy cells that's the billion doll question and hopefully with continued research we can figure it out sometimes the less exciting part of our educational experience is just memorizing information yes it is important to memorize and retain information but if you can't apply that information to real world situations that information isn't as useful so having teachers or learning platforms that can help you develop application skills is invaluable and that's why we partnered with brilliant as the sponsor of today's video brilliant is an incredible way to take your learning to the next level as brilliant is an interactive online learning platform with thousands of lessons in math science data analysis programming and even AI Brilliance lessons are designed

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