This came from a website that sells information called "canceranswers.com". They give some information free and then sell a report if you are interested. So far in my research, this description and explanation of cancer of unknown primary (origin) is the simplest and clearest I've found. CANCER OF UNKNOWN ORIGIN TREATMENT INFORMATION The simplest living component of the human body are it's individual living cells.
There are many types of cells within the adult body, but they all arose from a single fertilized egg cell implanted in the womb. This cell was "pleuri-potential", meaning it contained all the information necessary to construct a new human body. Astoundingly, every single body cell (except the sperm and egg cells) retains the total amount ("complement") of information to construct a duplicate person! This information is carried by the tiny "genes" in each cell, which are themselves compacted into a substance called "DNA" which forms the 48 chromosomes within every human cell. Normally, much of the genetic information is "masked" within cells as they divide and develop ("differentiate") from previous cells.
Only the information needed to perform their specified function is readily available. This accounts for why cells specialize to become brain, bone, cartilage, muscle and fat cells, for example. Cells themselves are arranged into network structures called "tissues", such as heart tissue, lung tissue, eye tissue and kidney tissue. The blood is a circulating tissue. Furthermore, various tissues can be further combined to form "organs" like the brain, pancreas and larynx (voicebox). Moreover, at a higher level, organs can be integrated into "organ systems" such as the respiratory, digestive, nervous, and reproductive systems. Thus increasing levels of complexity and sophistication are seen as the human develops, but every part of the body can be defined by it's cellular components.
The cells comprising a fledgling human grow very rapidly in the womb, in early childhood, and through puberty. In adulthood, new cells are only formed to replace those which have died from injury, old age or disease. The division of cells to produce new ones is under tight control by the "genes" within each cell. and if they become damaged, the cell may start dividing out of control. Cancer starts in a single cell which has become abnormal. This cells produces millions, and eventually billions, of copies of itself. The copies are called "clones". These clones fail to function as normal esophagus tissue, but instead divert resources from healthy cells to fuel their own growth. When there are about 1 billion cells, they form a clump, or "tumor" 1/2 inch across. A "tumor" merely means a swelling, it can be caused by infection, inflammation, cancer or whatever. If a tumor only grows in it's local area (even very large) but does not have the capacity to spread to distant body areas, it is called "benign" and is not cancer. If, however, the tumor has the ability to spread to distant body areas, it is called "malignant" and this is cancer.
The actual process of spread is called "metastasis", and can occur to any area of the body. It is this ability to spread that makes cancer so dangerous. Patients rarely succumb to the growing tumors themselves. Rather, cancer most commonly kills by causing anemia (lowered red blood cell count), infection (due to a lowered white blood cell count), and bleeding (due to lowered blood platelet count). We also see interference with normal organ functioning, and a general debility arising from malnutrition, dehydration, and multiple metabolic disturbances. While modern medicine can extend the lifespans of most cancer patients by partially correcting these disturbances, only completely eliminating the "malignant clone" of cancerous cells from body will cure the disease. What is Cancer of Unknown Origin?
Every cancer initially arises from somewhere. Usually, the location where the first cells turns malignant ("transforms") to start a cancer is obvious, since an enlarging tumor becomes apparent there . The location where a cancer first starts is called the "primary site". The cancer then spreads into adjacent tissues by "local extension", that is direct growth from the primary site. An example is a bone tumor extending into the muscle and fat surrounding the bone. Next, the cancer commonly spread into the "lymphatic system" which is comprised of a network of tiny "lymph channels" which drain the tissue fluid with bathes body cells with oxygen and nutrients [there is not a blood vessel connecting to every cell; instead the blood fluid ("plasma") seeps out of the smallest blood cells to supply groups of cells and absorb their waste products, and this fluid is collected by the lymphatic system]. The lymph channels carry their fluid to normally pea-sized "lymph nodes", which are packed with white blood cells.
These lymph nodes tend to occur in clusters, called "glands". They purify the plasma, killing bacteria and trapping cancer cells. When they detect something foreign in the plasma, such as a germ, allergen or cancer cell, these lymph glands swell up ("lymphadenopathy"). As an example, there are about 400 lymph nodes in the neck region and people often note swollen "glands" in their neck with a strep throat. Ultimately, the lymph glands interconnect via lymph channels, and all of the lymph fluid eventually drains back (into the "left thoracic duct" nearby the heart) to rejoin the bloodstream. The point of all this is that cancer can spread from the primary site to local lymph glands ("lymphogenous dissemination") causing them to swell, and then to more distant lymph glands. The lymph glands closest to the primary tumor are called "first eschelon" nodes, and more distant ones are called "secondary nodes" and named by their anatomical location.
Cancer can also spread ("metastasize") from the primary site via the bloodstream, since individuals cancer cells can be sucked ("embolized") into local small blood vessels ("capillaries"). This process is called "hematogenous dissemination", and can spread the cancer to ANY living area of the body. This is basically "seeding" of the cancer to fertile areas where "metastatic tumors" (as distinguished from the initial "primary site") can flourish. Certain areas of the body seem more "receptive" to trapping cancer cells from the bloodstream and promoting their growth. These areas are those that have good blood supply and complex loose fibrous networks that trap cells, such as the lungs, liver, bones, brain and skin. In fact, these environments may prove more hospitable for tumor cell growth than the primary site, resulting in a larger "metastatic tumor burden" (bulk) than the size of the initial tumor! Thus, the more obvious appearance of the cancer may well be to the site(s) of spread, rather than the area it started in. All cancers are described by where they putatively started, and the areas that they have spread to ("involved").
However, in a minority of cancer patients (5 to 10%) not only is the site of spread more evident than the "primary site", but the site of origin is not apparent at all! This is called "Cancer of Unknown Primary", (or "Unknown Origin" or "Occult Carcinoma") and represents a serious dilemma for treatment. Sometimes the "primary site" can be intuited with great accuracy. An example is when the lymph nodes in the armpit ("axilla") only are involved with cancer in a woman with high risk for breast cancer-- the likely origin of the cancer is in the breast on that side of the body, even if nothing shows up on physical exam or mammogram of that breast. On the other hand, sometimes the origin may be very perplexing and nearly impossible to discern, such as when a single lump of non-skin cancer arises on the torso, and could have arisen from any number of inapparent areas. Then the cause ("etiology") of cancer is unknown, and may either become apparent over time, be deduced from medical inquiry, or may never be known. As will be seen, many cancers which are originally classified as "Unknown Origin" will ultimately "declare themselves" with careful investigation, but about 20% will remain unsolved.
The origin of a cancer may be inapparent for several reasons. Firstly, a cancer is not generally detectable with any of our radiology procedures until it is at least 1 cm. in diameter (about 1 billion cells), but it may have spread to a more fertile area for growth before getting this large at the "primary site"-- and thus go unnoticed there. Also, the original cancer site may have outstripped it's blood supply, and died, but managed to "seed" the bloodstream before disappearing in it's primary site. Likewise, immune processes (white blood cells) may have successfully detected and destroyed the cancer when it was small at the primary site, but (unfortunately) not before it had managed to metastasize to an area where the immune system is less effective (i.e. brain or bone). Another possibility is that the whole of the primary cancer "shed" away into the lymph system and bloodstream, simply leaving no remaining cancer cells in it's orginal area. Sometimes the original site of the cancer simply dies ("apoptosis") from genetic instability or other unknown reasons. Finally, there may be tissues in the body in the wrong places (called "ectopic tissues") which resemble normal tissue counterparts, but become cancerous. Thus, tissue resembling the thyroid may be found in the ovary, or resembling bone may be found in the lung. If these abnormal areas become cancerous (as they are prone to do) then we may fruitlessly search the normal area of that tissue (i.e. thyroid or bone) for the primary site-- but there is none to be found. Thus, we can understand why a Cancer of Unknown Primary may or may not eventually have it's area of origin discovered, and also that if we successfully treat the area(s) of metastasis, we may in fact have no cancer cells remaining in the body.
The origin of most cancers is obvious, either by looking at which organ the original tumor started in or at a sample of the cancer cells under a microscope. Rarely however a cancer will be found in skin, muscle, fat, glands, bone or brain and it is apparent that the cancer started elsewhere. This is because the cancer cells found at the site of spread are different types of cells than would normally be found in that area. Even after medical workup, the site of the original, or "primary" cancer, cannot be determined. This is a Cancer of Unknown Origin, also called "Occult Cancer".
It is critical to get prompt and proper treatment for an Occult Cancer, this can literally make the difference between life and death. Often the "primary" is never found, and so doesn't become a clinical problem. With competent analysis, however, the primary may be found and treated, possibly saving the patient's life.
CancerAnswers' material explains, in plain English, the definition, frequency, symptoms, evaluation, historic and latest effective treatment for a Cancer of Unknown Origin. We tell you everything you must know to help make the right decisions for this cancer problem today.
This is just an excerpt of CancerAnswers's report on Cancer of an Unknown Origin.
