Why We May Never Cure Cancer
Among all the diseases and ailments that we face, Cancer stands as one of the most fearsome of all. Cancer is a major cause of death in the modern world. In 2015, cancer has caused 8.8 million deaths, globally. It’s easy to understand why cancer receives a lot of scientific attention and many resources are used to study it. Oncology, the study and treatment of tumors, is a major branch of medicine. Cancer research is still on the rise, as shown by the fact that the appearance of the word ‘cancer’ in medical journal articles has grown from 28,000 in 2007 to 120,000 in 2017.
If so much effort is being poured into cancer research, Why are more people diagnosed with cancer every year? Is cancer a result of our modern lifestyles? How come we still don’t have a cure for cancer? Well, I would like to take a closer look at cancer and how it develops. I trust it may help us understand the answers to these questions. Despite the fact that modern medicine is getting better at treating cancer, I believe that we will never be able to cure cancer outright. Allow me to explain.
Cancer, by definition, is abnormal cell growth in the body that has the ability to spread across the body. The name Cancer is credited to the Father of Medicine, Hippocrates (460-370 BC). The name is rooted in the Latin and Greek words for crab: Cancer and Karkinos, respectively. A cancerous growth typically has many blood vessels protruding to its sides, a property that gives it a visual resemblance to a crab and its many legs, hence the name.
Cancer is an umbrella term that covers many diseases that have some common properties. There are over one hundred types of cancer. The types are usually classified by the organ they formed at or the type of cell they originate from. Carcinoma, for example, is a type of cancer that develops from epithelial cells. These include most breast, prostate, and lung cancers. Sarcoma is a type of cancer that develops in connective tissues. These include the bones, cartilage and fat cells. Lymphoma and Leukemia are types of cancer that form in the blood cells and later mature in the lymph nodes or the blood.
All of these types, and a few others, fit under the term Cancer because of the way they come to be and how they affect the body. All types of cancer have this in common: they are caused by genetic mutations that cause cells to divide and proliferate abnormally. In a way, a cancerous cell ignores the ‘rules’ set by the body, ceases to work synchronously with the other cells and divides unstoppably. The proliferation of faulty cells leads to a partial lack or full absence of functionality of the organ that hosts these mutations and often of surrounding tissues, as well.
Mutations that lead to cancer can occur in almost any type of cell in our bodies. Every cell has a nucleus, in which the genetic material, the DNA, is stored. Most cells cannot live forever and so they divide to grow and sustain tissues that make up our bodies. Each cell divides at a different rate - some every few hours, while some divide only once or even never during our whole lifetime.
When our cells divide, the DNA of the cell is wholly replicated and so each cell has a copy. The DNA encodes for the proteins and enzymes and everything that the cell needs to function. Part of the functional genes that our DNA contains are oncogenes and tumor-suppressor genes; oncogenes are genes that are responsible for cell growth and division, while tumor-suppressors are genes that inhibit growth and stop cell division if it may pose a danger to the body.
We have an unimaginable number of cells in our bodies (estimated to be over 37 trillion). Each has a copy of the entire genetic material that is needed to form every mechanism that sustains our bodies. Our cells have very efficient and reliable mechanisms that ‘copy and paste’ the DNA, but a mistake will naturally happen every once in a while. These mistakes are called mutations. A single mutation or a combination of a few may lead to harmless changes, like a different hair color, or even cause no change at all. However, a mutation may lead to an abnormal expression of oncogenes or tumor-suppressor genes.
If oncogenes are over-expressed or tumor-suppressors under-expressed in a cell, then this cell may divide in an uncontrollable manner. When this happens, cells that originate from the mutated cell will also possess the mutation and will keep dividing in the same manner. This aggregate of unnaturally dividing cells is what we call a tumor.
A crucial property of cancerous tumors is that they metastasize. These tumors tend to spread to nearby tissues, and sometimes a few cells may break off and spread via the blood system, thus disseminating the disease in our body. When a cancerous tumor metastasizes, harmful cells may end up practically anywhere in the body, at this point the lethality rates soar. When you have one defined tumor, it can be surgically removed. This treatment is relatively easy and effective. But when a tumor spreads, it may become nearly impossible to find and treat, making it highly dangerous.
A cancerous tumor may present with no symptoms and it is not always lethal. As it grows, it can ulcerate or appear as a noticeable lump. It may affect the well-being of nearby organs, which might lead to symptoms that fit other diseases. A tumor in the lungs, for example, can block the bronchus and cause coughing and bleeding, symptoms that are similar to those of Pneumonia. With time, the tumor will interfere with the function of the system it affects. Interrupting crucial functions of the body will lead to lasting damage or death.
Mutations might naturally occur sporadically, but there are many external factors that can cause mutations that lead to cancer. In fact, most of the cancer-causing mutations are happening due to external factors. Between 90-95% of cancer cases are caused by genetic mutations from environmental factors, the rest from hereditary and spontaneous mutations.
Environmental factors include anything that is external to the body and may cause changes to the DNA or its expression. For example, ionizing radiation from medical devices or the sun can damage our DNA and call for extra repairs, thus increasing the chances for a mutation to occur. External materials that enter our bodies may cause changes in our internal environmental conditions (such as pH or salt levels), this may consequently affect the efficiency of our DNA replication and expression mechanisms.
Materials that affect the body and cause increased mutation rates are called Carcinogens. These include many substances that we may encounter, sometimes very often, in our daily lives. Polluted air, smoke from cigarettes, alcohol, materials found in processed meats, materials used in different industries and even UV wavelengths in sunlight can cause mutations. A combination of a few carcinogens increases the chances of cancer development by a fair margin. In the western world, the numbers of two of the leading lethal cancers - lung and colorectal - can be considerably decreased by lifestyle changes that include more physical activity and avoidance of alcohol and tobacco, for example.
That does not mean that cancer is a disease that is rooted in our modern way of lives. Smoking and drinking alcohol has been common for centuries. Radiation from the sun is nothing new for us. Even if we eliminate all of this factors, cancer would still be a part of our lives.
Despite the somewhat popular belief that cancer is a problem of the modern world, cancer has been with us since we came to be. Hereditary and spontaneous mutations have existed since the first cell divided way back when. Cancer-causing environmental factors are thought to be exacerbated in the modern world, but even if we could eliminate them we would still face cancer. The increased number of cancer cases we see today is mostly attributed to one factor - age.
Age is a major factor in cancer development. Most invasive cancer patients are over the age of 65. Errors in DNA replication that have accumulated over a lifetime, along with age-related changes in our bodies increase the chances for cancer development. Rates of cancer cases are increasing as people live longer today than ever before. In the past, people died from any other reason before reaching an age where cancer is more prevalent. Many scientists believe that if we would have lived long enough, we all would have developed cancer at some point.
This information might give the impression that cancer is just waiting to strike but it should comfort you to know that the human body does its very best to prevent cancer. We have a few inherent lines of defense that stand between us and cancer. The first line of defense is the body’s DNA repair mechanisms. When a mistake is put into the DNA sequence, our cells are pretty good at identifying and fixing the mistake. If our DNA is damaged, our body can rebuild the damaged area with rather good precision. The second line of defense is halting the life cycle of a cell. If a certain amount of damage or inconsistency in the DNA sequence is detected, enough to pose danger to the body, the cell will not go into the stage of mitosis (cell division) until these mistakes are fixed. The last line of defense is programmed cell death, or Apoptosis. When the cell crosses a line beyond which the damage is too much to repair, or if there’s a chance that the cell may pass on dangerously mutated DNA, the cell will eliminate itself in a controlled manner, for the good of the whole. These lines of defense are not perfect and every once in a while these mutations do manage to get passed them.
Between mutations occurring intermittently and our body’s defense mechanisms, there are three properties that a cell has to maintain to become cancerous. The first property is that the cell divides even without a clear signal to divide. A cell usually divides based on signals in the form of hormones or growth factors. A cancerous cell is always going towards cell division, it does not wait for an order to do so. The second property is the absence of the self-destruction mechanism of the cell. This mechanism is mainly based on two genes - RB1 and TP53. These genes regulate cell division by making sure that the cell does not divide uncontrollably or when it’s damaged in any way. In a cancerous cell, these mechanisms are overridden or are not functioning correctly. The third property is that the cell can divide an unlimited amount of times. A healthy cell has a limit to the number of times it may divide, depending on a structure at the end of the chromosomes, known as the Telomere. These telomeres are made of repeating DNA sequences that erode with each division and when they are gone, the cell will not be able to divide anymore. Cancer cells have the ability to restore the telomeres and thus multiply indefinitely, spreading the disease.
So why we may never have a single cure for cancer? Well, by definition, cancer is intrinsic to a genetic system as ours. While mutations may cause adverse effects, they are not necessarily negative and are an integral part of our development and evolution. Our DNA encodes for every function our body requires and a mutation in the code for one of the functions that coordinate our cells will happen every once in a while and these may lead to a form of cancer. Despite the fact that external factors can cause these mutations, cancer is not an external disease, like an infection. It is, in a way, part of our DNA. For cancer to occur, it sometimes takes over a hundred different mutations. Some types of cancer share a few common mutations, but the combinations of mutations that lead to cancer are endless. There simply will not be a cure that fixes each one of this combinations. Cancer treatment is getting more efficient with each year that passes, but we may never cure out cancer altogether.
It is important to know, though, that all of the effort and resources that we put into cancer research seem to pay off. The number of cancer patients rises each year, but that is mostly due to the fact that there are more of us around and we live longer than ever before. But take lung cancer as an example; it is a common type of cancer and a leading cause of death that is showing a decline in the death rates every year since the early 90’s, and the 5-year survival rate is increasing. The knowledge we amass from cancer research allows for better diagnosis of cancer, more effective treatments and minimizing their side-effects. These days, there are a few novel ideas for techniques to tackle cancer that utilize modern technology that might one day lead to new types of treatments. These may seem futuristic today and they are still in their early stages, but they might one day prove useful enough to change the perception that we hold of cancer today.
There's always more to talk about - read some more in the Additional Notes to this article.
Thank you so much for reading this article!
Daphne Semus Cyprus.