HOW DO CELLS FUNCTION?

Cells are the basic building blocks of the bodily structures. Cells attach to and interact with each other to form, say, the liver, the lungs, or the bones. Each cell, in turn, functions as its own mini factory, contributing to general function of the organ ot os a part of (for example, enabling the stomach to digest food) and ensuring its own self-preservation. A single organ contains billions of cells. The cells comprised by an organ, however, differ from each other and may contribute to different types of tissues within that organ. For example, certain cells within the lungs form the major lung tissue, called lung parenchyma that gives lungs their substance. Other cells within the lungs form the tough, fibrous structures that surround the lungs and give them their shape. Still other cells contribute to the blood vessels that supply the lung tissue with blood, while entirely different cells make up the nerves associated with the lungs. Any one of these cells could potentially develop into a cancerous cell; this explains why so many different types of cancers might arise in the same organ.

The blueprints for a cell’s function, development, reproduction, and eventual death are contained in structures called DNA (short for deoxyribonucleic acid). The DNA, in turn, is combined to form chromosomes, and chromosomes are housed in a central cell structure called the nucleus. The machinery that carries out the cell’s functions is found in the area surrounding the nucleus, called the cytoplasm.Cells reproduce by dividing into identical halves. These halves then mature, carry out the same functions as their parent, and in turn divide to form four identical cells, and so on. As an individual grows from embryo into a fetus and then into infancy, childhood, and finally adulthood, the number of these dividing cells exceeds the cells that are being replaced (older, dying cells), and organs and tissues grow. Once an individual reaches adulthood, though, cell division slows to keep pace with cell loss, and organs and tissues maintain their size.

Most cells live for a given amount of time (this can very from minutes to years) and then udergo programmed cell death, a process called apoptosis. It is as if each cell came with its own, predetermined expiration date, brought about by its own DNA. As cells age, they lose some or all of their ability to function. They then can no longer contribute as much to the organ or body part to which they belong, and that organ or body part will therefore not function as well. For example, an aging platelet (a cell in the bloodstream whose job is to facilitate blood clotting) will not stem bleeding as well as a young platelet that has freshly entered the bloodstream from the bone marrow. Apoptosis is the body’s built-in mechanism for removing these dysfunctional cells so as to keep its organs operating as efficiently as possible.

WHAT IS THE NORMAL STRUCTURE AND FUNCTION OF AN ORGAN IN THE BODY?

Every organ in the body performs specific duties. Each organ functions as a member of a community of organs, all contributing to the good of the body as a whole. The brain, the "high commander," dictates the functions of most organs. The heart pumps blood (at varying rates and pressures, depending on the brain's signals) to other tissues and organs, the lungs breathe air (providing necessary oxygen to tissues and organs via the bloodstream), and the stomach digests food (providing nutrients to itself and other organs and tissues in the body). The pancreas and gallbladder assist with that digestion, while the liver and kidneys help to process and excrete toxins from the body. The reproductive organs (ovaries in a woman and testes in a man) ensure that the elements that define the individuality of a person (the genes) get passed on to the next generation. Every organ is composed of tissues; tissues are, in turn, composed of cells.

The human body has evolved with a complicated set of organs, each of which performs specific functions and each of which relies on and communicates with other organs for the good of the whole individual. The brain, for example, controls higher-order functioning (memory, thought, sensory input and output) and basic bodily functions (breathing, the beating of the heart, the drive to eat and sleep). It transmits electrical signals to the heart to beat faster or slower, to the movement. It also sends out hormonal signals through the release of chemicals from the pituitary gland. These signals affect other organs, including the heart, lungs, kidneys, reproductive organs, and thyroid gland. The organs affected by the brain then vary their function, in turn sending out signals (either electrical, chemical, or both) to still other organs, then back to the brain to provide "feedback" about how the organ is responding to the brain's initial stimulus.

A scenario may clarify these interactions. You are walking in the forest one day when a tiger jumps out from the bushes. Your brain thinks, "Oh my God, it's a tiger! I'm in trouble!" - a process known as "higher-order functioning." It then transmits electrical signals to the heart to beat faster, to the lungs to breathe harder (basic bodily functions), and to the muscles to tense up, preparing you to flee from or to fight the tiger (your choice!). At the same time, the brain triggers to the pituitary gland (also located in the skull) to release hormones, including one that stimulates the adrenal glands to produce adrenaline (epinephrine). Adrenaline also in turn, send signals back to the brain to tell it "Okay - we're really moving now! You can stop signaling us to work harder. We're already doing it!" (feedback). These organs work together to ensure survival.

Organs, then, perform specific functions, but they also respond to both electrical and chemical stimuli from other organs, all for the good of the individual.

IS CANCER CURABLE?

The short answer to this question is yes. In fact, all cancers are curable if they are caught early enough. That is the justification for screening tests (such as mammograms, colonoscopies, and prostate exams). When cancers are caught early, they tend to be smaller, they are thus either easier to remove surgically or more likely to shrink in response to chemotherapy or radiation therapy.

Cancers not caught early enough (when they are no longer small in size or few in number) still may be curable and almost certainly are treatable. Even advanced cancers - malignancies that have spread to different parts of the body, or have metastasized - usually are treatable. Often, they are thought of as "chronic diseases." or diseases that a person will live with over a long period. While a given therapy may not cure a disease, it may extend a person's life until a more promising and potentially curative therapy becomes available.

WHY DOES HAVING CANCER MAKE A PERSON FEEL SICK?

Some types of cancer release chemicals that make a person feel ill. These chemicals, called cytokines, may cause fevers, chills, sewats, fatigue, anorexia (loss of appetite), or even nausea and vomiting. These are the same chemicals that are released into the bloodstream when a person has the flu, which explains why the tumor necrosis factor, or TNF, used to be called cachexin, because its release from cancer cells was associated with cachexia, or wasting. These symptoms are, in fact, the ones that often bring a person with cancer to a doctor's attention in the first place. As a cancer continues to grow, these chemicals continue to be released. Treating the cancer should alleviate these symptoms.

WHY NOT JUST LET THE CANCER GROW?

In some cases, this may be the right thing to do. As some people have cancers that grow slowly, exposing them to either surgery or chemotherapy may make them sick without doing much to improve their survival. Older adults, in particular, are more prone to experience the side effects or therapy; if those side effects outweigh the potential benefit or therapy or the potential harm of living with cancer, the proposed therapy may not be of benefit. This is where the notion of "quality of life" becomes important. Alternatively, a person may be ideologically opposed to therapy; for such an individual, letting the cancer grow might be the right thing to do.

In other cases, letting the cancer grow may not be the right thing to do. Unfortunately, many cancer cells do not respect the boundaries of other organs or body structures. A growing cancer might press on another organ and prevent that organ from functioning normally, or it might actually invade an organ and impair that organ's function. Then, a situation may arise in which bleeding or an infection occurs. A lung cancer, for example, might press on the esophagus (the tube that carries food from the mouth to the stomach) and block the transit of food. A person with such a cancer might describe a sensation of "food getting caught in my throat - I just can't get it down." Alternatively, if the cancer invaded a blood vessel in the lungs, bleeding would occur, and the person might describe episodes of "coughing up blood."w

WHAT MAKES CANCEROUS CELLS STOP GROWING?

Cancer continue to grow unless one of four things occurs:

1. The cancerous mass is removed by a surgeon
2. Chemotherapy or another type of cancer - specific medication, such as hormonal therapy, is given to the person with cancer
3. A person with cancer receives radiation therapy
4. The cancer cells shrink and disappear on their own. This last event, while extremely rare, can occur with some melanomas (a type of skin cancer) or some kidney cancers
   

WHERE IN THE BODY CAN CANCER DEVELOP?

Cancer can occur anywhere in the body. Any area of the body that you can name can be the target for a cancer. Some cancers even arise in parts of the body that contained structures only when the person was just an embryo - just week after conception! Cancer cells - those abnormal cells that have lost the ability to stop growing - arise from cells that used to be normal components of organs and tissues. What causes cells to become cancerous? Cells grow abnormally because of environmental factors (such as cigarette smoking or radiation exposure), a genetic predisposition, "dumb luck", and as yet unexplained causes. Just "dumb luck" accounts for the majority of cancers.

Examples of Tumor Types and How They Are Categorized:
Liquid Tumors :

• Lymphoma
• Leukimia
• Multple myeloma

Solid Tumors:

• Lung Cancer
• Breast Cancer
• Prostate Cancer
• Colon Cancer
• Rectal Cancer
• Bladder Cancer
• Brain Cancer
  

WHAT IS CANCER?

Put simply, cancer is the abnormal growth of cells. Cancers arise from an organ or body structure and are composed of tiny cells that have lost the ability to stop growing. This growing mass of cells then projects from that organ or body structure until it becomes large enough to be noticed by a patient or physician. Occasionally, cancer may be detected "incidentally" by a laboratory test or x-ray - that is, the test or x-ray may have been ordered for purposes of routine screening or for an entirely different reason; in such a case, the cancer gets noticed almost by accident. at this point, it may be referred to as a "mass", "growth", "tumor", "nodule", "spot", "lump", "lesion", or "malignancy."

In general, the cancer must reach a size of 1 centimeter (that is, between 1/3 and 1/2 inch), or be made up of 1 million cells, before it is detected. Exceptions to this general rule include cancers of the blood and bone marrow - called lymphomas, leukemias, and multiple myeloma - which frequently do not produce a mass but will be evident on laboratory tests; these cancers still require more than a million cells to be present before they are detected. Lymphomas and Leukemias are examples of "liquid tumors," or cancers present in body fluids (the blood and bone marrow), and are detectable by laboratory tests of the blood. "Solid tumors" including cancers of the lung, breast, prostate, colon, rectum, and bladder - are not present in large enough numbers in body fluids to be detected with a blood test. However, they may release chemicals that are detectable in body fluids. A person with prostate cancer, for example, may have an elevated level of prostate - specific antigen, or PSA, in the blood-stream.