So cancer is a disease, we're all familiar with it. But essentially, the basic definition of cancer is that it is abnormal, or can be unregulated growth. It's a little bit more difficult to term, but abnormal cell growth and division is a key feature. So you're getting a ton of cell growth, cells are growing in size, and they're dividing. And, generally what we term this whole cell growth and division is called proliferation. In cancer, it's unregulated, it's uncontrolled; it is going all over the place, proliferation, which is cell growth and division. And if you get a lot of cell growth and division, eventually, that's going to develop into a tumor. But it's not only cell growth and division that is unregulated; it's also unregulated death. And so, cell death is called apoptosis, and that is a process that is this whole regulated pathway that tells cells when it's time for them to die. And unregulated and uncontrolled apoptosis also causes cancer, because you're getting these cell growths, you're getting these divisions, and nothing's telling them, "Oh, wait. You're growing too much. You're dividing too much. It's time to die." So it's this combination of growth, division, and unregulated death that allows for these tumors to grow. And, in order to affect cell growth, division, and death, it requires multiple mutations. A lot of people think, "Oh, cancer is one mutation, and that leads to cancer," but actually what makes cancer difficult to treat is that it's an accumulation of mutations. And those mutations are different for every cancer and for every individual. So we call cancer, you know, a disease, like, we say breast cancer. But everyone's breast cancer is different because they all have different mutations and different genes. There may be some common ones that we're familiar with, like the BRCA genes in breast cancer. Those are very commonly found in breast cancer cells, but each one of those, even if they do contain BRCA, also has to contain other mutations that can vary in different genes, in different positions, throughout the genome. So these multiple mutations exist. And because there's multiple mutations, we say that cancer cells are genetically unstable, and this is a really common term that you hear when describing cancer. And so what that means is that there's just a ton of mutations and even chromosomal aberrations, meaning that there's chromosomal breakage, chromosomal inversions, sort of transitions. All these different things that we've talked about in different chapters are commonly found in cancers. And so, we just sort of say, "You know, cancer cells have a lot of these; therefore, they're genetically unstable." Now there are two types of cancerous tumors. The first is benign. And these are still cancer. Right? This is still cancer. It's created a tumor. It has unregulated cell growth division and cell death. But the positive part of benign tumors is that they're proliferating abnormally, but they're contained to a single area. So if you have a benign tumor and it's causing problems, a surgeon can just go in, chop it out, and you may need a little bit of extra cancer therapy. But, generally, the prognosis or the survival rate of people with benign tumors is extremely high because they're confined to this one area, and you can just go and take them out. Whereas, malignant tumors are much more dangerous because they metastasize, which means they travel to other areas of the body. So they may have started out in the breast, but then they go to the brain. And that's very dangerous. So they may have started out in the kneecap, in the bone in the kneecap, but then they travel to the liver. And it's very difficult because you can't just take out, you know, your kneecap and then also your liver, and then also part of your brain, because that is very difficult. It's very harmful to your body. You can't just cut out one single benign tumor and expect that to work for a malignant tumor. So an example of this is if this is an organism, you have a benign tumor, it has very clear edges here, and a surgeon can just come, cut this region out, and then the cancer is mostly gone for the most part. Malignant tumors are much more difficult because if a surgeon comes in, it can cut this much out. Well, you're still left with these regions here that may travel and exist in other organs, or elsewhere throughout the body, and it can be very dangerous. Now tumorigenesis is a term you're going to see, and what that is is it's the development of the tumo
Table of contents
- 1. Introduction to Genetics51m
- 2. Mendel's Laws of Inheritance3h 37m
- 3. Extensions to Mendelian Inheritance2h 41m
- 4. Genetic Mapping and Linkage2h 28m
- 5. Genetics of Bacteria and Viruses1h 21m
- 6. Chromosomal Variation1h 48m
- 7. DNA and Chromosome Structure56m
- 8. DNA Replication1h 10m
- 9. Mitosis and Meiosis1h 34m
- 10. Transcription1h 0m
- 11. Translation58m
- 12. Gene Regulation in Prokaryotes1h 19m
- 13. Gene Regulation in Eukaryotes44m
- 14. Genetic Control of Development44m
- 15. Genomes and Genomics1h 50m
- 16. Transposable Elements47m
- 17. Mutation, Repair, and Recombination1h 6m
- 18. Molecular Genetic Tools19m
- 19. Cancer Genetics29m
- 20. Quantitative Genetics1h 26m
- 21. Population Genetics50m
- 22. Evolutionary Genetics29m
19. Cancer Genetics
Overview of Cancer
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