All right. This lecture will be an overview of cancer, and we're going to start off by talking about what is cancer? Well, the first thing you need to know is that cancer is the second leading cause of death. About one third of deaths from cancer are due to things like tobacco use, obesity, low fruit and vegetable consumption, and lack of physical activity. Of course, when you see a list of four of the primary contributors to cancer, what does that suggest to you? Hopefully, it suggest that these are four of the factors that actually are under our control that we can change. Any case, I'm moving on to some more specifics here about 9.6 million people worldwide are estimated to die from cancer or did die or estimated to die from cancer 2018. In the United States, the total economic cost of cancer was estimated to be about 1.16 trillion in 2010. As I just mentioned a minute ago, if you look at this list of causes, these are all on behavioral and under our control. So about 30-50 percent of cancers can be prevented. Some of these stats come from the World Health Organization, they have a nice summary of cancer on the website. So moving on, in terms of what exactly is cancer in terms of the biology of it, this is to say 30,000 foot overview of what happens with cancer. Well, basically when we talk about cancer, we're talking about a collection of related diseases with a commonality, which basically is that cells begin to divide uncontrollably. So normally, human cells grow. New cells are formed as the body needs them, and the body gets rid of older damaged cells. When cancer develops, that whole process breaks down. With cancer, older damaged cells survive when they should die off and new cells are not forming when they're not needed, and then there's extra cells divide without stopping and form tumors. So this is just a quick graphical depiction of what we're talking about here. On the left-hand side, we have normal cell division. When there's a damaged cell or mutation in a cell, that cell is either repaired or if it's not repaired, it basically undergoes apoptosis or cell death, so as a way to get rid of a damaged cell. With cancer cell division, you end up with some cells with the mutation and then a second mutation, a third mutation is just an example, and fourth mutation, and then you end up with uncontrollable growth. It is this uncontrollable growth that is the primary feature of cancer. So some tumors, may be not all of them, spread into or invade nearby tissues. Those are the ones that are called malignant tumors. Some cancer cells can break off and travel through the blood, the lymph system and form new tumors and more distant places which obviously is really bad. We also have benign tumors that do not spread into or invade other tissues. When those are removed, usually they don't come back and they don't require any further treatment. So it's this cancer that spreads throughout the body obviously is the very deadly kind of cancer. So we talked about normal cells turning into cancer cells, but how's that happen? Well, typically, there's some external agent. Something causes a genetic mutation and that something can be ultraviolet radiation, it can be chemical carcinogens like asbestos or components of tobacco smoke, it also can be biological in nature like viruses or bacteria or parasites. I mentioned this already twice actually, but you can't really mention it too many times, 30-50 percent of cancers can be prevented, at least that's the thinking, by avoiding risk factors and by implementing evidence-based prevention strategies. This is according to the World Health Organization but consistent with our National Cancer Institute and the American Cancer Society too. Again, some large portion of cancers can in theory be preventable. So age is a fundamental risk factor for cancer, and of course that makes sense. Because the older you are, the more you've accumulated exposure to carcinogens. Also of course the older you are, the cellular repair mechanisms aren't nearly as effective when you're older. So let's talk for a minute about tobacco, and alcohol, and cancer, and these are two agents that contributes substantially to cancer. So tobacco smoking is linked to 15 different cancers, alcohol use has been linked to seven different types of cancer. These are a couple of cool infographics that I picked up from the cancer research people in the United Kingdom, the UK, but this on the left-hand side is just an illustration of alcohol. In fact, that's linked to a seven different types of cancer. Things like mouth and upper throat cancer, breast cancer in women. Then over here, we see basically I'm smoking, if you stop smoking, that can help prevent 15 types of cancer. So these are the types of cancers that are related to smoking. So again, I'll call on cancer to preventable causes of different kinds of cancer. The third one I want to highlight here is obesity, being overweight can also contribute to different types of cancer. In this case, the infographic is summarizing the relationship between being overweight and 13 different types of cancer including things like breast cancer and bowel cancer. Now, we're going to switch gears a minute, and let's just talk about cancer and anxiety. So put yourself in the shoes of a cancer patient. When you're first diagnosed with cancer, obviously there is initial shock, and there's fear, and there's anxiety, and that continues all the way through while you're waiting for a treatment plan. You can imagine that, especially if it's a serious kind of cancer, there are thoughts of dying and thoughts of death, and all of this elicits extreme anxiety. Then, when you get a treatment plan, there's going to be even more anxiety because now your doctors are talking about side effects like hair loss, the pain, nausea, vomiting, and so obviously that's going to jack up the anxiety even more. Then you may think well, after treatment, especially if the cancer is gone, maybe things will be gone too. But the truth is that cancer patients talk about anxiety about the return of cancer. So obviously, you're anxious about will the cancer come back. So it's not surprising at all. Then one in three cancer patients experience major mood disturbances, both anxiety and depression. Survivors of cancer are much more likely to experience subsequent mood disturbances. Definitely, there's been an effort to target that aspect of cancer, and there are a number of treatments out there, traditional psychological interventions like mindfulness and relaxation, cognitive behavioral therapy, things of this nature. So cancer anxiety is an important component. Then another important piece here is cancer and pain. The tumors themselves can produce pain by putting pressure on bones and nerves, by putting pressure on the spine organs. A chemotherapy often induces peripheral neuropathy, which we've talked about before in the context of type two diabetes. But basically, there are a whole slew of issues that go on with chemotherapy. As I mentioned peripheral neuropathy, but also mouth sores are a common problem. So there's definitely pain involved with chemotherapy. When you get to the radiation phase, once again, the pain is a part of that. Then of course, surgery can be a significant source of pain. Lumbar puncture, which is common in some forms of cancer, also significant source of pain. So cancer and pain, that's another important piece. Then another one is cancer and sleep. So you can imagine that sleep disruption and sleep problems are pretty common. We just finished talking about sleeping in the last module. Of course, if you're getting less sleep, then it makes everything worse in terms of the pain, anxiety, and so forth. So difficulty in falling asleep is an issue, awakening in the middle night, problems maintaining sleep, insomnia are all common. So the etiology varies by type of cancer and treatment. Again, these things are interconnected. So pain contributes to sleep problems, sleep problems contribute to the experience of pain. Obviously, if you're nauseated and you're vomiting, that's going to make it hard to sleep. Then one of the issues here too is that sleep problems can become chronic. So even once you're past chemotherapy stage or the radiation stage, if you've been experiencing sleep problems for six months, there's a chance these are going to become a chronic problem even though you're now in a different phase of your treatment for cancer. So it's also worth noting that 30-50 percent of prescriptions that cancer patients get are for hypnotics, again suggesting that sleep is a big complaint. So in conclusion, cancer is the second leading cause of death worldwide, close to 10 million people died in 2018. One third of cancer cases are attributable to behavior and consumption of substances like tobacco, and alcohol, and obesity. Then the following symptoms are quite common in cancer patients. So anxiety and stress, pain, sleep disturbance, and then other side effects also from chemotherapy and radiation. Then finally, treatment involves treating the cancer itself as well as the symptoms listed above. So obviously, your doctors are not just focused on treating the cancer, but they are also focused on helping their patients with sleep, anxiety, pain, etc.
