CHAPTER ONE: WHAT IS CANCER
(keywords and concepts, cancer development, lung cancer,
role of lymph nodes, development of lung cancer, links to lung cancer sites )
1.0 A DEFINITION OF CANCER
A medical text defines cancer as "a cellular malignancy whose unique trait- loss of normal controls- results in unregulated growth, lack of differentiation, and ability to invade local tissues and metastasize."(1) These three characteristics, abnormal growth, lack of appropriate differentiation, and capacity to invade other tissues or organs are common to different types of cancers. While these characteristics are common in various types of cancers, the extent of each may vary. For example, as we see in chapter three, small cell lung cancer will metastasize more quickly than non-small cell lung cancer.
1.1 HOW AND WHY DO NORMAL CELLS CHANGE TO CANCER CELLS
1.11 Normal Cells Divide and Multiply
While one characteristic of cancer cells is their ability to multiply, normal cells do that too. Dr. Norman Coleman explains:
Cells do all kind of things, including divide into more cells: one cell can divide into two cells, each "offspring cell" can divide into two cells, and so on. Cell division occurs at various times and for various reasons: cells divide during the growth and development of the embryo and the fetus, for example, and when there is a need to repair an injury in the body, such as a scraped need. Cells also divide in cancer- cancer occurs when they divide out of control (2)
Why do we have genes in our system whose whole purpose is apparently to create abnormal cellular development? The answer is we don't. Oncogenes are genes which malfunction under certain conditions: AThe term proto-oncogenes is misleading because if wrongly implies that these genes latently reside in the genome for the sole purpose of expressing the neoplastic phenotype, when in fact they are essential to the normal biological processes such as cell division. The risk of errors (e.g. chromosomal translocations) which activate their oncogenic potential suggests that numerous safeguards preventing facile activation of oncogenes must exist.
1.2 HOW DO NORMAL CELLS KNOW WHEN TO MULTIPLY- THE ROLE OF GROWTH FACTORS
Cellular division and replacement is a normal process in the body: Cells in many parts of our body are growing. We are aware that our our fingernails and hair, for example. Other areas are not growing bigger, but the cells within them are multiplying. Such growth is necessary because almost all parts of the body are subjected to daily wear and tear that kills cells, or damages them, or makes them fall off. For instance, every day we lose many millions of cells from the lining of our mouth, and the digestive tract. The cells that are lost are replaced daily by new cells created by growth and multiplication.
1.21 How do Cells know when to divide:
Cells divide only when they receive the proper signals from growth factors that circulate in the bloodstream or from a cell they are in direct contact with. For example, if a person loses blood, a growth factor called erythropoietin, which is produced in the kidneys, circulates in the bloodstream and tells the bone marrow to manufacture more blood cells. Growth factors that come from outside the cell can transmit a message by binding to the appropriate receptor on the cell surface (the key and lock) triggering a signaling system that activates a specific gene in the cell's nucleus. Other signals generated within the cell itself can use the signaling system to activate a gene.z
1.5 HOW ARE GENES DAMAGED AND HOW DO NORMAL GENES BECOME ONCOGENES
A normal gene can become damaged in different ways. A cell can become abnormal when part of a gene is lost (deleted), when part of a chromosome is rearranged and ends up in the wrong place on a chromosome (called a translocation), or when an extremely small defect occurs in the DNA, which results in an abnormal DNA blueprint and production of a defective protein.
1.51 Time for Cancer to Develop
Cancer does not develop overnight though some people will associate an cancer with some event or exposure that happened a few months before. Instead, as we explain in chapter two, most tumors are associated with a series of changes that may occur over a period of 10 to 15 years or even longer. (7).
1.52 Primary SitesThe place where the cancer begins is called the primary site and the cancer that initially forms is the primary cancer.
1.7 HOW DO CANCER CELLS METASTASIZE
Cancers have no enclosing structure to keep them in place, and therefore their natural tendency is to travel and expand. Perhaps the most serious malfunction in cancer development is the tendency of cancerous cells to metastasize, that is, invade neighboring structures, and transmit the cellular malfunctions to those cells. As cancer cells grow and form a clump or tumor, they may also invade neighboring normal areas. How do cancer cells escape?. Cancers have no enclosing capsule, so their cells can escape and be transported by the lymph circulation or the bloodstream to other organs..
1.72 How do Cancers Penetrate the Natural Protective Barriers in Cells and Organs
Once the cancer cells come in contact with another organ, they succeed in breaking down the normal barriers or frontiers that keep that organ=s cells in order. Often the frontier or boundary that separate one group of normal cells from the next is quite easy to see when the tissue is examined under a microscope; and is called a basement membrane.
legal claims based upon the failure to timely diagnose lung cancer.
LUNGCANCER LINKS AND SITES
A list of lung cancer links, sites, and organizations. Partial list below.
Howard Gutman is a New Jersey attorney based in Parsippany, New Jersey who has handled numerous legal claims involving pulmonary tumors. A member of the board of directors of a leading cancer support group, he has been an advocate for early detection programs and is the author of the upcoming book, A Complete Guide to Lung Cancer.