In the health care realm, everyone has heard of cancer and knows it causes tumors which can kill, but what, exactly, is cancer?
While no definition fits all cancers, the disease usually is characterized by cell growth and multiplication that is unregulated or not in coordination with adjacent tissues.
Such activity forms tumors, which can spread elsewhere in the body, often via blood circulation or the lymphatic system.
Cell growth and division is normal. It heals wounds, replaces skin and hair, and turns children into adults. In many cases, cancer seems to be these routine processes gone awry.
“It is an abnormality of what would otherwise be normal,” said Dr. Daniel Murphy, an oncologist with Tahlequah City Hospital. “The human body grows from one omnipotential cell in a fertilized egg.”
Cancer cell behaviors are caused by a series of mutations in the regulatory genes. More genes are progressively damaged until the cells are out of control. Though cancer can afflict children, it is much more common in older people, which suggests a series of genetic mutations are required to create a cancerous cell.
“Genes may be turned on which should be off, or off when they should be on,” Murphy said. “Skin cells stop growing when they touch each other, but if the inhibition isn’t turned on, they can continue to grow. Cells can even turn into different cells, or do what we call ‘dedifferentiate’ and become less specialized.”
Some researchers believe cancer is the unavoidable fallout of the genetic mutation process, which occurs naturally over generations, though there is much professional disagreement with the theory.
“It is true that there are genetic predispositions to cancer,” Murphy said. “A typical chance of an older person getting cancer is 1 in 8 over 15 years. But a young person with a family history may have a 50 or 60 percent chance of getting cancer in the same timeframe. However, many cancers are caused by environmental factors - carcinogens such as smoking, sunlight, asbestos.”
Cancerous tumors, or malignant neoplasms, are different from benign neoplasms, which do not spread. More than 200 types of cancer can afflict humans.
Reasons for potential lethality vary with the type of cancer, but in general, cancer kills by diminishing or interfering with the function of the tissues in which it is present. The spread of lung cancer reduces the amount of healthy tissue to absorb oxygen, or tumors can obstruct part of the lung and cause a mortal infection. Cancerous bone marrow interferes with blood cell production, or might release a deadly amount of calcium into the bloodstream.
Modern medicine offers many cancer patients an all-fronts approach, which may include radiation treatments, chemotherapy, adjustments to diet and lifestyle, exercise and counseling. But medical researchers are excited about the future possibility of personalizing cancer treatments based on biomarkers - which may help predict the behavior of cancers - and genetic inhibitors.
“Actually, we personalize treatment with the conventional tools of today,” Murphy said. “We are getting better at it, with better technologies and fewer surgeries and side effects. It is important for people to understand that cancer isn’t as lethal as they think. It is the most curable chronic disease there is. Heart disease can only be treated, not cured. About 70 percent of cancers are cured. It is the great medical success story of the last 20 years.”