Lung cancer complications

Voiceover: What I want you to remember about the main complications that arise from lung cancer is that they can all be explained by the growth of the cancer mass of cells itself, by the spread of the cancer cells throughout the body, by the immune response to the cancer, and by the inappropriate release of hormones by the cancer cells. When you keep those in mind, the complications that come with lung cancer become more logical and intuitive. How about we go through these categories, and I'll explain the complications within each more in-depth. Let me take the second while I'm erasing all the categories besides mass, so we can start there, that there are two types of lung cancer. Non-small-cell and small-cell. Some complications occur more frequently with one type versus the other, and so when that comes up I'll highlight it for you. OK, done erasing, on to mass effect. Let's zoom in on the lung lining, where the source of all of our problems begins with dividing cancer cells. And as the cells continue to divide, the tumor is going to get bigger, and compress the airway nearby. This is going to make it difficult for air to come in and out of the lungs. Do you see that? That's going to cause wheezing and shortness of breath. But some air might be able to get past the tumor, and it might be carrying with it some pathogens, that I'm showing with this star, that can lead to lung infections if they can't get back out around the tumor. So, OK, growing mass of cells compresses nearby structures. Got it? Now use that same logic here. Let's predict the complications of a Pancoast tumor. This is a fancy name given to a tumor that grows at the very tippy-top of the lungs. At the periphery of the lung, here, where many types of non-small-cell lung cancers tend to grow, and where there's a lot of nerves controlling other parts of the body. Like the nerve that runs down the side of the lungs and controls the diaphragm. This is the muscle that helps us coordinate breathing. Now that we know the Pancoast tumor could compress this nerve, diminishing control of the diaphragm, that would make it a challenge to breathe, right? Let's do this again. Another important nerve at the top of the lung here controls the voice box. So compressing it means what? It's going to make generating voice sounds difficult, and a patient may have a raspy or a hoarse voice as a result. What about the nerves here that go into the face? Compressing these nerves causes Horner's syndrome, where a patient experiences drooping eyelids, constriction of the pupil, which is the central black part of the eye, and decreased sweating, but only on the same side of the body where the tumor is located. So here, on the left side. But what else is in this region? On the right side is the superior vena cava. This is the large vein draining blood from the upper limbs and the face back to the heart. And if the mass compresses this vein, blood won't drain efficiently, and will cause swelling as blood backs up into the face and the upper limbs. Keep in mind that if this tumor mass were a little bit lower and more centrally located in the chest cavity, it would still have the same effect on the superior vena cava, but it would be caused more commonly by small-cell lung cancer, since tumors of this type tend to grow more centrally. Now let's move on to the spread of cancer cells from the lungs to other parts of the body, where additional complications can occur in that body system. Meaning, if they spread to the brain, would you be surprised at this point if I told you that this would cause central nervous system problems, like dizziness and seizures? What about spread to the bones? Bone weakness, bone pain, fracture might occur, right? Lung cancer cells like to spread to the liver, because it's a nearby organ, and if they spread there a patient may be jaundiced as a sign of liver dysfunction. The organ that sits on top of the kidneys, the adrenal gland, is also a popular place for lung cancer to spread, for the same reason. It's conveniently located nearby the lungs. Here the cancer cells can change the levels of hormones secreted by the adrenal gland and cause endocrine complications, like, for example, diabetes. Let's jump up here to the hilar lymph nodes just outside the lungs, and mediastinal lymph nodes in the center of the chest, because we really can't forget that cancer cells can spread through the blood, but they can also spread through the lymphatic vessels. One more close-by location is the space immediately surrounding the lungs, that's filled with a lung-cushioning fluid. In both these fluid-filled locations, the lymph nodes and surrounding the lung, an inflammatory response by the immune system to the cancer cells causes an increase in fluid volume, meaning that all nearby structures of these sites are compressed. Again, remember that these locations are closest to the lungs, so that means they're an attractive first site for the cancers to spread to. Speaking of inflammation, let's use this as a segue. Let's erase some of the sites of cancer spread and talk more about the immune response to cancer. Cancer cells anywhere in the body will cause an immune response, which means inflammation and an ongoing fever are all complications of lung cancer. But one more very specific complication involves the muscles of the body. Muscles work by receiving signals from nerves. But in certain types of small-cell lung cancer, the immune system produces antibodies against the cancer that also interact with the neurons. The antibodies diminish the neurons' ability to signal to muscles, and this causes muscle weakness and dysfunction. And finally, for our last category of complications, I'm going to bring in this table that I was working on, and we can complete it together. These complications have to do with the hormones that the cancer cells gain the ability to produce, which knock off the delicate balance of endocrine signalling in the body. I want to note that these complications are rare, but they're not infrequent, so I want to talk about them still. One complication that can occur with non-small-cell lung cancer is the release of parathyroid hormone-related protein. Maybe you've heard of this type of hormone abbreviated as PTH. It regulates calcium in the blood. Having too much of it, because of the release from the cancer cells, means that calcium is removed from the bones and is instead found in high concentrations in the blood. This leaves the bones weak and prone to breaks. In small-cell lung cancer, cells can begin to secrete anti-diuretic hormone. I often forget that that's what ADH stands for, and ADH regulates the amount of water found in urine. So let me draw a kidney here, and increased amounts of ADH leads to decreased urine volume, because the body is retaining more water. This causes bloating and increased blood pressure. It also means that the body is trying to compensate by excreting more sodium to try to have the water follow the sodium out of the body. But the cancer cells are stopping this re-balancing from occurring. Finally, the last complication from small-cell lung cancer is ectopic Cushing's syndrome. This syndrome involves the increased secretion of adreno-corticotropic hormone. This hormone causes the release of corticosteroids from the adrenal gland. As these corticosteroids increase because of the cancer cells, it causes a decrease in immune function and leads to immune suppression.