A Brief Introduction To Cancer
There is a chance that when you hear the word ‘cancer,’ you panic a little. Someone you know may have had or has cancer. Or it could be you. We tend to associate this word immediately with death.
Why is that?
When I was younger, my parents explained how my uncle died. They told me he had died of cancer. At the time, I did not fully understand what the disease “cancer” was, but I did comprehend that it was extremely deadly.
Because it happened decades before I was born, I did not see first-hand the pain that comes with losing a loved one to this disease or had the desire to research more about the illness. However, last year, my friend’s mother died of cancer. I was with her before and after it happened, and I know how much it has affected her life. Before her mother died, she talked to me about how her mother was improving and how well she was receiving the treatment.
Until one day, it all went downhill.
She told me that her mom had gone to the hospital and that there was a full 180 of how her condition was. Just a couple of days before, she was doing relatively well. But it all disappeared that day once my friend told me what had happened. Her mom’s condition decreased rapidly over a span of three days, and it was just a matter of time until my friend had to say goodbye.
Once it occurred, she was devastated.
You might wonder, why am I telling you this? I am doing this because I want you to understand that cancer is a prevalent societal problem. As well, the illness has been here for a long time. According to the Canadian Cancer Society, “2 in 5 Canadians..are expected to develop cancer during their lifetime. About 1 out of 4 Canadians…is expected to die from cancer.” Even though the numbers can be scary, there is hope. Cancer research is moving forward to find ways to help cancer patients become healthy once again. In this article, I will explain briefly what cancer is, the ten hallmarks of cancer, and treatments used to combat this disease.
Cancer, to put it simply, is life in abundance. It happens when cells do not stop multiplying. Healthy cells become this way by going over several changes and modifications the body’s immune system was not able to find.
In the following diagram, it is possible to see the different stages a healthy cell goes through to become cancerous. There is hyperplasia, where there is an increase of cells in an organ or tissue that appear normal under a microscope. In dysplasia, the cells appear abnormal under a microscope but are not cancer. After these two stages, there is a possibility that the cells can become a tumour, but there is also a chance they will not. This is possible because of mutations in the cell’s DNA.
DNA is the building block of life since it stores information on the cell’s genetic code. There can be changes to this genetic code, but most of the time, our cells pinpoint the modification and destroy it in a process called apoptosis. Apoptosis is the natural process cells undergo to die. It is programmed cell death. This method is a crucial cancer prevention tool as it stops cells from multiplying.
The disease is damaging as it overtakes healthy cells by stealing nutrients, leading to the destruction of these healthy cells. Once the cancerous cells multiply enough, a tumour appears. Please watch this animation that shows how cancer divides:
Cancer is harmful as it overtakes healthy cells by stealing nutrients, which leads it to kill these healthy cells. Once the cancerous cells multiply enough, a tumour appears. There are risks when this happens. The biggest one is the possibility of metastasis. Metastasis is the process by which cancer cells spread to other parts of the body. Most of the time, this process occurs when cancer cells enter the bloodstream and start a secondary tumour in another area. Once a tumour does this, it becomes harder to destroy as it is found somewhere else. Moreover, most cancer deaths occur once the tumour goes through this process.
The Ten Hallmarks of Cancer
The ten hallmarks of cancer are characteristics necessary for a tumour to become malignant. These abilities are crucial for a healthy, normal cell to become malignant tumours. The ten hallmarks of cancer are the following:
- Sustaining proliferative signalling.
Cancer cells decide their cell growth, which means that they do not need other cells to help them with growth signals and no longer depend on external signals. They can increase, the growth of tissue cells, constantly in the absence of stimuli.
2. Evading growth suppressors.
Cancerous cells avoid anti-growth cells by evading growth suppressors. That leads them to uncontrollable cell division. They resist inhibitory signals that might stop their growth. The major ones are Autophagy and Apoptosis, which can lead to cell death and reduce the size of the tumour.
Autophagy is the cell’s recycling mechanism that rids the body of impurities like degradation of cytoplasmic contents, abnormal protein aggregates, and excess or damaged organelles. This is important to create new necessary components. Cancer cells can increase the level of autophagy to increase their survival in stressful environments. Moreover, with this system, cancer cells can increase their growth and aggressiveness.
Apoptosis, or cell death, can be induced by activating death receptors. The loss of apoptosis allows cancerous cells to survive longer and gives more time for mutations to appear.
3. Avoiding Immune Destruction.
Some cancer cells can adapt mechanisms to evade detection and destruction from the host’s immune system. The cells do this by taking over mechanisms from the immune checkpoint control. These immune checkpoints are built-in mechanisms from the immune system that maintain self-tolerance and help avoid unnecessary damage with an immune response. Cancer cells create conditions to hide from the immune system and its attack by evading the immune checkpoints.
4. Enabling Replicative Immortality.
Cancer cells can become a “pre-differentiated, stem-cell-like phenotype,” which allows them to have zero restrictions on cell division and adaptations that allow them to enable survival in difficult conditions. Two signalling pathways have the biggest impact on these changes and they are Hippo and Wnt β-Cantening signaling.
Hippo signalling is a pathway that controls the sizes of organs by regulating cell proliferation, apoptosis, and stem cell self-renewal. Once the cancer cells suppress this pathway, it contributes to cancer development.
Wnt β-Cantening signalling is another type that, when it’s enabled, allows cancer to divide indefinitely. This signalling “regulates stem cell pluripotency and cell fate decisions during development.”
5. Tumor Promoting Inflammation.
Cancer cells hijack inflammatory mechanisms during tumour-promoting inflammation to promote their growth and survival. The usual immune system response is to engulf or destroy foreign invaders. However, within the tumour environment, this function is corrupted and changed by cancerous cells.
6. Activation Invasion and Metastasis.
There are two processes that cancer cells go through to invade local tissue and spread to distant sites known as invasion and metastasis. Tissue invasion refers to the mechanisms that tumour cells use to expand into nearby environments. Metastasis is the process where tumour cells break away from the primary tumour, move to a new location and establish a secondary tumour.
7. Inducing Angiogenesis Energetics.
Cancer cells can stimulate the growth of blood vessels to supply nutrients to them. Angiogenesis is a term referring to the formation of new blood vessels from pre-existing blood vessels, which plays an important role in a tumour’s growth.
8. Genome Instability and Mutation.
Since no cancer cells are equal, they evolve as a response to pressure-driven accumulation of mutations. Cancer cells must “out-compete nearby cells for nutrients and other resources, avoid immune cell attack, and suppress apoptotic self-destruction.”
9. Resisting Cell Death.
By evading apoptosis, cancer cells can resist cell death. Usually, apoptosis helps an organism stay healthy throughout its growth and development by removing infected or damaged cells to maintain body tissue. However, cancer cells do not follow this process, they grow abnormally.
This is achieved by cancer cells altering the mechanisms used to find damage or irregularities, which prevent the proper signs of light to activate apoptosis.
10. Deregulating Cellular Energetics.
A characteristic of cancer is that they grow fast, and to do this they need a lot of energy. For cancer cells, pyruvate from glycoside is directed away from the mitochondria, where it would go to in a healthy cell, “to create lactate through the action of lactate dehydrogenase (LDH/LDHA) — a process typically reserved for the low oxygen state.”
Cancer Treatments
Cancer is a complex and harsh disease that alters the life of an organism once it occurs. It steals nutrients from healthy cells to benefit itself and eventually kills these healthy cells over time. Cancer’s characteristics allow scientists to see a pattern of how it evolves and changes over time to become stronger and more resilient towards treatment. They can pinpoint the proteins, and receptors, among others, to fully understand what is making a cell become malignant. This can contribute to the development of treatments.
In the last few decades, cancer deaths have been slowly declining. Scientists have made significant progress throughout the years, and they still do so today. This has happened because cancer treatment has become more precise and new treatments have been created. Scientists also discovered more about the disease, and more people started being aware of what can cause it.
These therapies can be used together since sometimes a cancer patient may need more than one to combat the illness. There are multiple cancer treatments, but the most common are radiation therapy, surgery, chemotherapy, and immunotherapy.
Radiation Therapy
Radiation therapy, also called radiotherapy, is a cancer treatment that focuses on high doses of radiation and gradually eradicates a tumour. Cancerous cells become damaged beyond repair, which causes them to stop developing and die. More than half of people with cancer will receive radiation therapy as treatment.
The team of doctors taking care of a patient can choose to use radiation as the primary treatment or alongside another treatment, like chemotherapy or surgery.
Radiotherapy is most effective on head and neck, breast, cervix, prostate, and eye cancer because it is usually only used by itself. This therapy is used often since “4 out of every 10 cancer cures include radiotherapy as part of the treatment plan.” However, radiation therapy requires multiple sessions for the treatment to be effective. As a consequence, results are not seen right away. If doctors use radiation therapy, the five-year survival rate of patients is 27%.
This therapy also has a lot of side effects and they may affect the patient’s health. They last depending on the time and dose the treatment was given for. Most of them will be gone after a few months, but some side effects take longer to disappear. This happens because of the damage this therapy has on healthy cells. Some of the side effects of radiation therapy are headaches, hair loss, nausea, vomiting, extreme tiredness (fatigue), hearing loss, skin and scalp changes, and troubles with memory and speech.
Surgery
Cancer surgery is prevalent in diagnosing and preventing the disease. It can be used in different areas. These are cancer prevention, diagnosis, staging, primary treatment, and debulking.
CANCER PREVENTION: In some cases, the cancer can be destroyed by extracting the organ before the tumour can develop. This process helps prevent the cancer from becoming extremely deadly.
DIAGNOSIS: Surgery might be used to get a sample from the tumour to get information about whether it is benign or malignant. These results aid doctors to come up with a plan for the patient.
STAGING: Cancer surgery can let doctors see the size of the tumour and if it has moved around the body, which also tells them what stage the cancer is in. This knowledge informs doctors how urgent and aggressive the treatment must be.
PRIMARY TREATMENT: For numerous types of cancer, surgery is the main, or primary, treatment.
DEBULKING: There are some situations where the cancerous tumour cannot be fully taken out with surgery. When this happens, doctors use a surgical removal called debulking, which is employed to remove as much of the malignant tumour as possible.
Cancer surgery is more effective on most types of cancer before the disease metastasizes. Furthermore, this treatment is most successful with tumours contained in one area, not like blood cancers or lymphatic cancers. 72% of cancer patients are still alive after two years of having surgery.
The side effects of cancer surgery depend on the type of operation the patient is having. The risks that are shared among multiple cancer operations are pain, infection, loss of organ function, fatigue, bleeding, blood clots, and altered bowel and bladder function.
Chemotherapy
To put it briefly, chemotherapy is like a poison to the body. It is a drug treatment that uses strong chemicals to kill fast-growing cells. It targets specifically fast-growing cells because cancer fits into this category.
Cancer cells undergo mitosis at a much faster rate than other cells in the body. To identify what chemotherapy drugs a patient will use, the doctors can ask patients about their type of cancer, the stage of cancer, and the patient’s overall health. This is necessary as there are plenty of types of cancer chemotherapy drugs.
The success rate of chemotherapy varies depending on the type of cancer and the stage of the cancer. For example, for patients with localized colon cancer, the five-year survival rate is 90% during the early stages.
There are a lot of side effects when it comes to chemotherapy, and these are caused by the qualities of the cells the treatment targets, which are the fast rate of cell division. Some types of non-cancerous cells that multiply rapidly in the body are skin cells, digestive cells, or hair cells. They are also affected by the chemotherapy drugs because of this characteristic. Several side effects are nausea, vomiting, diarrhoea, hair loss, loss of appetite, fatigue, fever, mouth sores, pain, and constipation.
Immunotherapy
Immunotherapy is a cancer treatment that aids the immune system in fighting cancer. Naturally, the immune system identifies and annihilates abnormal cells and helps prevent the growth of many cancers. It is the defence mechanism of the human body. However, cancer cells can develop a way to avoid destruction by the immune system. This treatment aids the body in destroying and identifying cancer cells by boosting the immune system through substances created by the body or in a lab. This therapy can improve the long-term survival of patients with cancer.
Immunotherapy treatments are most effective with blood cancer, lung cancer, head and neck cancer, bladder cancer, kidney cancer, and Hodgkin lymphoma. This treatment is extremely helpful as it enables the immune system to identify and target cancerous cells and reaches places where radiation or surgery cannot get to.
The success rate of immunotherapy, for patients with early-stage lung cancer, is 80%. This number is higher compared to standard treatments, which have a 36–68%.
The primary side effect immunotherapy causes is the immune system to be more aggressive and start to damage healthy cells and tissues. Like chemotherapy, immunotherapy can harm healthy cells. These side effects result from overstimulated or misdirected immune responses. For instance, the treatment has the potential to affect any tissue or organ in the body. The side effects can be treated with steroids or other immunosuppressive drugs. They can be affected by the type of cancer and the patient’s overall health. The common side effects associated with immunotherapy are arthritis, chills, constipation, coughing, decreased appetite, diarrhoea, fatigue, fever and flu-like symptoms, headache, hypopituitarism, hypothyroidism, infusion-related reaction/injection site pain, itching, muscle aches, nausea, rash, and vomiting.
Even though there are several side effects, there are also uncommon, more dangerous side effects. They include colitis, hepatitis, inflammation of the lung, or pneumonitis, kidney failure, myocarditis or inflammation of the heart, neuropathy, paralysis, meningitis, or encephalitis, pancreatitis, severe infections, severe skin reactions, and type 1 diabetes.
All of these treatments are still being developed today as advancements are made to make them less harmful and more effective for cancer patients. It is a progress that has been researched for many decades and will be researched for many other years to come. As more are found and developed, the chances of finding a “cure” increase, as well as the hope of patients and their loved ones.
One of the influential discoveries in cancer treatment was CRISPR-Cas9 in 2012. CRISPR-Cas9 is a genome editing tool that is cheaper, faster, and more accurate compared to previous DNA-editing techniques. This tool is not only used in cancer but in many different areas, like creating drought-resistant crops.
CRISPR-Cas9 allows scientists to remove, add, or replace parts of a genome in a DNA sequence. It works by using two key molecules, an enzyme called Cas9 and a piece of guide RNA (gRNA). Cas9 works as a pair of molecular scissors since it can cut two strands of DNA at a specific location. gRNA is a small piece of pre-designed RNA sequence, usually about 20 bases long. This is located within a longer RNA scaffold that binds to DNA and this sequence leads Cas9 to the desired part of the genome. This is necessary for the enzyme to cut in the right place of the genome.
This tool is exciting since it is quite simple, easy to use, and cost-effective. CRISPR-Cas9 is revolutionary because it allows scientists to modify potentially any gene from any organism.
Even though this technology is incredible, there are some ethical problems. Many believe there should be regulations to what extent this tool is used, why it is used, and how it is used.
Overall, cancer is a complex and deadly disease. Its characteristics make it hard to treat as it varies for each cancer patient. These characteristics help scientists understand how to find treatments for this disease and what areas they should focus on. The hallmarks of cancer are an example of these, as it helps them understand what truly is supporting cancer cells to thrive.
This disease affects many people around the world and destroys a person’s life. It brings pain and suffering to the patient and the people around them. However, cancer treatments try to help the patient as much as possible. New discoveries can help create new technologies to do so.
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