Cancer: How does it kill?
The term cancer refers to a group of related conditions in which bodily cells start to divide and grow uncontrollably, often spreading into surrounding tissue.
Cancer kills by growing into key organs, nerves, or blood vessels and interfering with and impairing their function. It can begin in almost any human cell.
Usually, new cells form through growth and division. Cells die once they become too old or damaged, and newly formed cells replace them.
Cancer disrupts the cellular destruction and renewal process. As a result, new cells become increasingly abnormal, and old cells live when the body should destroy them.
New cells also form when there is no need for them. These excess cells can begin to divide uncontrollably, forming tumorous growths.
Keep reading to learn more about tumor growth, how cancer spreads, and how it can lead to death.
Cancer is a genetic condition because it develops due to changes in cellular genes that control cell function, especially how they grow and divide.
A person can inherit these genetic changes from their parents. These changes may also develop due to genetic errors that occur when cells divide or when environmental exposure to toxins damages cellular DNA.
When a gene mutates or there are excess copies of it, it can become permanently switched on when it should not. These abnormal genes, called oncogenes, have the potential to cause cancer. Oncogenes cause cells to grow uncontrollably, which can cause cancer and tumors to form.
Changes in tumor suppressor genes, which normally help restrict cellular growth, can also trigger the growth of cancerous tumors.
In many cases, tumors are solid masses of abnormal tissue. That said, some cancers form in the blood, and these typically do not create solid tumors.
There are several differences between cancer cells and normal cells. It is these differences that allow cancer cells to form tumors that can cause organ damage, failure, and eventually death.
Unlike regular, healthy cells, cancer cells can grow and divide at an uncontrollable and very high rate. Cancer cells also do not mature and develop to perform highly specialized functions as normal cells do.
Cancer cells can also “hide” from the immune system, which normally destroys and removes abnormal or damaged cells.
Furthermore, cancer cells can also sometimes influence healthy cells, blood vessels, and molecules that nourish and surround tumors. For example, cancer cells can make normal cells produce blood vessels to supply the tumor’s oxygen and nutrient needs as they grow. These new blood vessels also remove waste.
Chunks of cancerous tumor can also break off and travel throughout the body in the blood or lymph system, forming new tumors in different locations. Malignant tumors also sometimes regrow after treatment.
Cancer cells or tumors in organs or the bloodstream can disrupt organ function. They may destroy healthy cells in organs, block their nutrient or oxygen supply, and allow waste products to build up.
If cancer becomes severe enough that it impairs or prevents vital organ function, it can result in death.
The list below outlines some examples of how different types of cancer ultimately cause death:
- Gastrointestinal cancers: These cause death due to malnutrition related to the blockage of the digestive system or an infection.
- Lung cancers: These can cause death due to lung collapse, infection, or lack of oxygen.
- Bone cancers: Increased calcium levels in the bloodstream and a reduction of healthy bone marrow reduces the body’s ability to fight infection, stop bleeding, and deliver oxygen to tissues.
- Liver cancers: These cause death due to a buildup of bodily chemicals and toxins.
- Blood cancers: These cause damage to blood vessels that can give rise to fatal, uncontrollable bleeding.
Some tumors are benign, or noncancerous.
Benign tumors can be quite large, but they do not usually spread. Most do not grow back after removal or destruction, and most do not result in death — though brain tumors can sometimes be life threatening.
Tumors can also be malignant, or cancerous. Cancerous tumors tend to spread and invade surrounding tissues, impacting their function or health.
With early treatment, the early stages of cancer usually do not cause severe symptoms or lead to death.
However, untreated later stage cancer tends to cause severe symptoms and has a higher likelihood of causing death.
‘In situ’ and early stage cancer
The sections below will look at early stage cancer in more detail.
This means that cancers or tumors are “in situ,” or where they originally developed. It means that they have not spread.
This stage is usually highly curable, often through the surgical removal of the tumor or cancerous cells.
Often called early stage cancer, stage 1 cancers or tumors are small and not deeply embedded in surrounding tissues. They have also not spread to other parts of the body or the lymph system.
People with stage 0 or 1 cancers may not notice any symptoms. Others may experience symptoms or notice changes to their body, such as:
- abnormal lumps, bumps, firmness, or swelling
- skin changes, such as new or changing moles, itchiness, scaliness, or becoming dimpled, discolored, darkened, puckered, or inflamed
- a cough or hoarseness that does not improve
- abnormal nipple or genital discharge or changes
- difficulty or pain when urinating
- blood in the urine or stool
- unexplained bruising
- changes in bowel habits
- abdominal pain
- nausea and vomiting
- reduced appetite
- difficulty eating or swallowing
- heartburn or indigestion that does not improve
- unexplained, severe exhaustion that does not improve
- unexplained fever or night sweats
- bleeding, pain, or numbness in the mouth or lips
- headaches and seizures
- vision and hearing changes
- white or red patches on the tongue or in the mouth
- sores that do not heal
- yellowing of the skin and eyes
- unexplained weight loss or gain
Later stage cancer
The sections below will look at later stage cancer in more detail.
Stages 2 and 3
Stage 2 and 3 cancers and tumors tend to be larger and have grown deeply into surrounding tissues. They may also have spread to other parts of the body or the lymph system.
Stage 4 is also called metastatic, or advanced, cancer. At this stage, cancers or tumors have spread to other parts of the body.
People with later stage cancer will experience different symptoms, depending on the type and location of their cancer. Nobody can entirely predict factors such as:
- what will happen at the end of the person’s life
- how long the final period of life will be
- whether or not death will occur
Some people die from cancer fairly quickly, especially if there were unexpected complications or the cancer was very severe. In other cases, it can take months or years.
However, as the cancer grows or spreads, it will start to impact multiple organs and the essential bodily processes they perform. This can cause a range of serious symptoms, including:
- intensified exhaustion and weakness
- a reduced ability to concentrate and think
- a reduced interest in things the person previously enjoyed
- weight loss and muscle loss or thinning
- appetite loss
- difficulty eating and swallowing
- requiring help with most activities
- needing to spend most time sleeping or resting
- a reduced interest in events taking place in the outside world
- wanting to limit time with visitors or only have a few people around
- drooping lips
- talking about things not related to current events or people present
- increased anxiety, loneliness, restlessness, or fear at night
- changes in heart rate, such as becoming more faint, irregular, or fast
- lower blood pressure
As someone approaches their final days with cancer, they may experience:
- noisy breathing, with gurgling, rattling sounds, and congestion
- cool, bluish to dusky colored skin, especially in the hands and feet
- slow breathing, sometimes with long pauses lasting for 10–30 seconds
- reduced urine output
- repetitive or restless involuntary movements
- dry mouth and lips
- loss of bowel and bladder control
- hallucinating or having dream-like experiences involving traveling, being welcomed by deceased people, or preparing for a trip
- confusion about place, time, and the identities of people around them
- a tendency to become gradually less responsive to external cues, such as voice or touch
- a tendency to drift in and out of a conscious state
- reduced speech or hearing
- blurry or dim vision
- difficulty closing the eyelids
When someone succumbs to cancer, their:
- pulse stops
- bowel or bladder empties uncontrollably
- eyes stop moving
- pupils enlarge and stay so, even in harsh light
- breathing stops
- blood pressure is undetectable
It is important to note that the symptoms vary greatly, depending on the type of cancer a person has and the organs it affects.
People with cancer die when tumors or cancerous cells impair organ function to the point where it can not perform vital bodily processes.
People with earlier stages of cancer may not notice any symptoms, or they may experience more subtle symptoms.
As the cancer progresses and spreads to multiple parts of the body, the symptoms tend to increase, as does the likelihood of death.
This article is from Medical News Today - How does cancer kill you? (medicalnewstoday.com)