Cancer is almost unbelievably horrible, from the potential hardship of treatment to the prospect of leaving grieving relatives behind. This terrible disease has a long range. According to estimates by the National Cancer Institute (19459006) (NCI), an estimated 1.7 million people were diagnosed with cancer in the United States in 2018. It is estimated that about 610,000 people will die of the disease by the end of the year.
Although the emotional and physical burdens of cancer are often clear, it can be confusing how cancer kills a person. Is it the cancer itself? Or is it usually a more indirect consequence of how cancer can affect a person's health? And does it vary depending on the type of cancer that a person has?
Depending on your situation, this can be a scary subject that you can discuss with a doctor or a loved one. But sometimes you even need answers to the scariest questions. Here we talked to several oncologists to explain how cancer can lead to death.
Cancer occurs when cells get out of control.
It can easily be forgotten how complicated human biology is, but your body is made up of a trillion-cell body. To function properly, these cells constantly grow and divide to form new cells, explains the NCI . In the normal cell cycle, cells that become old or damaged die and are replaced by newer, healthier versions.
Cancer forces this usual process to go terribly wrong. If someone has cancer, his old and damaged cells will not die and new cells will form for no reason. These cells can divide uncontrollably and, as a result, form tumors, says the NCI
Cancer is more likely to be fatal if it is metastatic, meaning it has spread throughout the body.  You may have heard of metastatic cancer but do not know exactly what it means.
Metastatic cancer occurs when cancerous cells invade surrounding tissues or even pass through blood or lymphatic systems to other parts of the body according to the NCI . These cells can then form tumors at their new sites.
Although metastatic cancer has by definition moved away from its place of origin, it is still considered a form of this primary cancer, explains the NCI . So, if you had ovarian cancer that spread to your stomach, this would be considered metastatic ovarian cancer, not gastric cancer.
It's often this spread – and its effect on one or more important organs – that eventually kills someone, Jack Jacoub, MD, oncologist and medical director of the MemorialCare Cancer Institute at the Orange Coast Medical Center in Fountain Valley, California, tells SELF , For this reason, the cancer staging largely depends on how extensive the cancer was . Stage IV cancer, the most severe form, means the cancer is wrapped up in distant parts of the body.
But metastatic cancer does not kill people in a certain way. Instead, this disease can take some ways to end a person's life.
These are the complications that are most likely to be fatal in cancer patients.
. 1 Malnutrition or Dehydration
Cancer can affect the function of your vital digestive system, which includes organs such as the stomach, pancreas and intestines. Tumors can clog up this system and create obstacles that can not get food or food waste, explains the NCI . This in turn can lead to problems such as frequent nausea and vomiting. However, cancer-related digestive problems are most likely to be life-threatening due to malnutrition or dehydration.
"The body stops using nutrients properly," Dr. Martin J. Edelman, Deputy Director of the Clinical Cancer Center at Fox Chase Cancer Center, tells SELBST. This means that even if someone receives nutrients via IV, they can die of malnutrition.
Malnutrition can be associated with difficulty in maintaining fluid level. " Dehydration is a side effect of advanced cancer almost everywhere," says Ishwaria Subbiah, MD, assistant professor in the department of palliative medicine and rehabilitation medicine at the Anderson Anderson Center, University of Texas, opposite the SELF.  While physicians can administer a patient with advanced cancer IV fluids, at some point it is difficult for the body to hold these necessary fluids. "The fluids do not stay where they are intended and penetrate from the blood vessels into the surrounding tissue," Dr. Subbiah. This can lead to dehydration.
. 2 Respiratory arrest
Irrespective of whether cancer originates from the lungs or that these organs are affected by metastasis, this disease can kill or block healthy lung tissue, which makes breathing far too difficult. NCI says.
Someone with advanced cancer can get oxygen in a facility like a hospital. However, this does not necessarily fix the problem if their lungs are unable to breathe, exhale, or transport oxygen and carbon dioxide through their respiratory system. A person with advanced cancer may have too much trouble over time to maintain the oxygen levels their body needs to survive, and their organs may fail, Dr. Dean says. Subbiah.
Cancer can also cause infection. This causes the lungs to fill with fluid, which may result in a person not getting enough oxygen over time, Subbiah says.
. 3 Loss of Brain Function
If cancer affects the brain it may lead to loss of consciousness, seizures, and the general inability of the brain to provide the required performance. Bryan McIver, MD, Ph.D., deputy chief physician of the Moffitt Cancer Center, tells SELF. Brain hemorrhages or injuries that affect the function of another critical part of the body, such as the lungs, can also kill someone, says the NCI .
Another complicating factor: The brain is in the skull's closed space So, there's no place to go when it swells with the pressure of a tumor, Dr. Subbiah. "In certain cases, the pressure is so high that it leads to a hernia in which part of the brain slips off the base of the skull ," she says. "This is always fatal in 19459205."
. 4 Bone marrow problems
Cancer can spread to the bone marrow, forming matter in the center of the large bones that forms new blood cells . If this happens, it can lead to a number of life-threatening problems.
A lack of adequate red blood cells can lead to anemia (too little oxygen in the blood) that can kill someone if he is strong enough . If your bone marrow can not make enough platelets to help your blood clots, it's harder to prevent heavy bleeding.
. 5 Infections
Cancer in the bone marrow can cause the white blood cells, which help to fight the infection, to sink to an extremely low level, says the NCI . In a related note, some cancer treatments, such as chemotherapy can override a person's immune system, increasing the risk of life-threatening infection, according to the American Cancer Society (1945S9070 (ACS)).
"Serious infections such as sepsis can be deadly, although someone may have another [local] infection, such as pneumonia or a urinary tract infection, which [become] could be severe," Dr. Edelman. The likelihood of this varies depending on the type of cancer someone has. Edelman. However, people with cancer in blood-forming tissues, such as leukemia are generally the most at-risk because the cancer can more easily kill too many white blood cells.
. 6 Blood clot complications
Unfortunately, cancer and cancer treatments can generally increase a person's risk of developing blood clots, ACS . There is also the fact that a person with advanced cancer is often in bed for a long time – another risk factor for blood clots . Together, this may increase the likelihood that a person will develop a blood clot that can lead to a fatal stroke or pulmonary embolism [a blood clot that blocks blood flow in the lungs]. med. Przemyslaw Twardowski, Professor of Medical Oncology and the Director of Clinical Research in the Department of Urology and Urological Oncology at the John Wayne Cancer Institute at the Providence Saint John's Health Center in Santa Monica, California, opposite SELF.
. 7 Liver Failure
Your liver juggles many important tasks, including removing toxins from your blood and supporting the digestion of food, explains the NCI . Cancer that starts in the liver or spreads through the liver can cause this organ to fail and to have difficulty performing these tasks. This can eventually lead to life-threatening complications such as excessive bleeding, including in the GI tract, and blood infections, says the Mayo Clinic .
. 8 Excessive calcium levels
When cancer damages a person's bones, too much calcium can enter their bloodstream, says the NCI . This is a condition known as hypercalcaemia, and it can destroy the ability of the heart and brain to function properly, according to the Mayo Clinic . This means that hypercalcaemia can lead to coma and death in severe cases.
Early detection and treatment often reduce the likelihood of these complications.
While physicians can treat some of these problems as they occur in otherwise healthy people, it is much more complicated in patients with advanced cancer, Dr. Subbiah. Often several things go wrong at the same time, which is why advanced cancer often causes fatal consequences. Dr. Subbiah explains, "These are not fixable issues if you put them all together."
This does not mean that all these complications are inevitable or even deadly when they occur. They are much more common and detrimental to advanced cancer, so experts explain why early detection and treatment are crucial. That is why there is hope for many cancer patients, especially in earlier stages.
"The rate at which people die of cancer has fallen ," says Dr. McIver. "We become much better at avoiding direct cancer deaths. And even if cancer can not be cured technically, it can often be controlled for years and even decades.