Cancers can occur any place in the body. Some are more specific to certain areas then others. Rather, cancers that have developed in one organ can spread to other areas. When cancer spreads, it’s called metastasis. Cancer develops through a multistage process in which gene changes remove normal controls over cell division. The development of cancer typically also requires the absence or mutation of at least one tumor suppressor gene.

In metastasis, cancer cells break away from where they first formed, travel through the blood or lymph system, and form new tumors in other parts of the body. Cancer can spread to almost anywhere in the body. But it commonly moves into your bones, liver, or lungs.

When these new tumors form, they are made of the same kind of cancer cells as the original tumor. For example, lung cancer cells that are found in the brain don’t look like brain cells. This disease would be called metastatic lung cancer. The goal of treatment is to stop or slow the growth of cancer or to relieve symptoms.

A cancer cell generally has an abnormally large nucleus and less cytoplasm than usual. It also is poorly differentiated. That is, cancer cells, often do not have the clear structural specializations of cells in mature body tissues. The extent of differentiation of cancer cells can be medically important. In general, the less differentiated cancer cells are, the more readily they break away from the primary tumor and spread the disease.

When a normal cell becomes transformed into a cancerous cell, additional changes occur. The cytoskeleton shrinks, becomes disorganized, or does both. Proteins of the plasma membrane are lost or altered, and new, different ones appear. These changes are passed on to the cell’s descendants. When a transformed cell divides, its daughter cells are cancerous cells too.

Uncontrolled Growth

Cancer cells lack normal controls over cell division. Contrary to popular belief, cancer cells does not necessarily divide more rapidly than normal cells do, but they do increase in number faster. Why? Normally, the death of cells closely balances the production of new ones through mitosis, (indirect cell division) so that the cells are arranged in an orderly tissue. In a cancerous tumor, however, at any given movement more cells are dividing than are dying. As this rampant cell division continues, the cancer cells do not respond to crowding, that is, the normal contact inhibition does not occur. A normal cell stops dividing once it comes into contact with another cell, but a cancerous cell keeps on dividing. Therefore cancer cells accumulate in a disorganized heap, which is why cancerous tumors are often lumpy.

When cancer cells are still contained in the tissue where they developed, it is called carcinoma in situ (CIS). Once those cells break outside the tissue’s membrane, it is called invasive cancer.

Carcinogenesis

The transformation of a normal cell into a cancerous one is a multi-step process called carcinogenesis. Cancer develops in most vertebrates, some invertebrates, and even some plants. Fossils show that some dinosaurs developed cancer. Wherever it turns up, cancer almost always develops through two or more steps in which genetic changes alter normal controls over cell division.

Heredity plays a major role in about 5 percent of cancers. If a mutation exists in a germ cell (sperm or egg), and if it alters a proto-oncogene or tumor suppressor gene, the defect can be passed on to offspring. The first step toward cancer suggest that several genes are involved, including genes that control aspects of cell metabolism and responses to hormones.

Viruses cause some cancers. Sometimes a viral infection can alter a proto-oncogene when the viral DNA is inserted at a certain position in the host cell DNA. For example, the viral gene could take the place of a regulatory sequence that normally prevents a proto-oncogene from switching on (or off) at the wrong time. Other viruses simply carry oncogenes as part of their genetic material and insert them into the host’s DNA. Most viruses linked to human cancer are DNA viruses, but RNA retroviruses are associated with some types of leukemia.

Chemicals 

There are thousands of known chemical carcinogens, cancer-causing substances that can cause DNA damage and subsequent mutation in DNA. Many of these chemicals are by-products of the industrialization of human societies, such as asbestos, coal tar, vinyl chloride and benzene. The list also includes hydrocarbons in cigarette smoke (as well as other types of smoke) and on the charred surfaces of barbecued meats (see my previous articles are high heat cooking), and carcinogenic substances in dyes and pesticides. One of the first carcinogens to be recognized was chimney soot (more accurately substances that soot contains). which frequently caused cancer of the scrotum in chimney sweeps. Plants and fungi can produce carcinogens; aflatoxin, a metabolic by-product of a fungus that attacks stored grain and other seeds, causes liver cancer. For this reason, some authorities advise against eating “raw” peanut butter. Commercial peanut butters are safe because processing kills the aflatoxin fungus. There are many other reasons why cancers develop and many causes are unknown.

Exactly where cancer cells will spread next is dependent on their location in the body, but it is likely to spread nearby first. Cancer can spread through:

Tissue – A growing tumor can push through surrounding tissues or into organs. Cancer cells from the primary tumor can break away and form new tumors nearby.

The lymph system – Cancer cells from the tumor can enter nearby lymph nodes. From there, they can travel the entire lymph system and start new tumors in other parts of the body.

The bloodstream – Solid tumors need oxygen and other nutrients to grow. Through a process called angiogenesis, tumors can prompt the formation of new blood vessels to ensure their survival. Cells can also enter the bloodstream and travel to distant sites.

It is easier to treat cancer before it has the chance to spread. Treatment depends on the specific type of cancer as well as the state. In many cases, treatment will consist of more than one therapy.

Surgery – Depending on the type of cancer you have, surgery may be the first-time treatment. When surgery is used to remove a tumor, the surgeon also removes a small margin of tissue around the tumor to lower the chances of leaving cancer cells behind. In my personal opinion, I believe that margins should be wide enough to ensure that cancers aren’t spreading. And that a pathologist examine the margins before the doctor closes the incision.

Surgery can also help stage the cancer. For example, checking the lymph nodes near the primary tumor can determine if cancer has spread locally.

Radiation and chemotherapy may also be added to the treatment plan after surgery. Sometimes this is an added precaution in case any cancer cells were left behind or have reached the blood or lymph system.

Radiation – Radiation uses high-energy rays to kill cancer cells or slow their growth. The rays target a specific area of the body where cancer has been found.

Radiation can be used to destroy a tumor or to relieve pain. It can also be used after surgery to target any cancer cells that may have been left behind.

Chemotherapy – Chemotherapy is a systemic treatment. Chemo drugs enter your bloodstream and travel throughout your body to find an destroy rapidly dividing cells.

Chemotherapy is used to kill cancer, slow its growth, and reduce the chances that new tumors will form. It is useful when cancer has spread beyond the primary tumor or if you have a type of cancer for which there are no targeted therapies.

Immunotherapy – Immunotherapies boost the power of your own body to fight cancer. These drugs can strengthen your immune system and help it recognize cancer cells.

Cancer isn’t a single disease. There are many types and many subtypes of this terrible disease. Some are more aggressive than others, but there are many variables that lead to different cancer characteristics. Your oncologist can give you a better understanding of the typical behavior of a certain kind of cancer based in the specifics of your pathology report.