Bone Cancer Treatment Information

BONE CANCER TREATMENT INFORMATION

General Information About Normal Bone

The bone is actually an organ system, meaning that it is made up of various tissues, which are in turn made up of specific cells. The bone system functions at two levels, one for structural support of the body (so we don't collapse) and one for the manufacture of blood cells within the "marrow space of the bone. There are specific cells that contribute to each of these two functions. In childhood the outer bone, called the "cortex," is made up of soft cartilage, which in turn is laid down by cartilage-forming cells called "chondroblasts." Gradually, as we mature, the cartilage is calcified into hard bone by cells called gosteoblasts."

Initially, the calcium is laid down in a rather haphazard pattern, so the bone does not have it's optimal strength. A secondary "restructuring" of bone occurs through puberty and young adulthood, where the initial calcified bone is re-absoted cells called "osteoclasts." The restructured bone is then laid down by osteoblasts in "Haversian Canals" which are cylindrical, run along the long axis of the bone, and resemble cement rods. These "canals" have a central blood vessel (bone is living tissue that needs blood for survival).

There are two basic types of bone in the body: flat bone and long long. Flat bones include those in the skull, vertebrae and ribs, while long bones are found in the extremities. The central skeleton contains the flat bones, and is called the 'axial" skeleton; the limbs contain the long bones which are called the "appendicular" skeleton.

While the outer shell, or "Otable" of each bone is the hard cortex, the inside of both flat and long bones is made of up the soft "marrow." The marrow is basically little spicules of bone with blood forming cells clinging to them, so it is very rich in blood. The marrow contains "stem cells," which are the 'precursor (first) blood cells from which all others arise. The cortex of the bone has nerves traveling through it, accounting for bone pain when the bone is injured. When a bone fractures, it forms a hard "callous" around the break, and amazingly this is even stroqger than the bone before breakage!

A balance is kept between the free calcium in the blood and the calcium in bone by hormones. If the blood calcium is too low, then some is reabsorbed from bone through the action of "parathyroid hormone" (PTH), produced by small glands in the thyroid. If the blood calcium is too high, it is deposited into bone by the hormone "Ocalcitonin," also from the thyroid. The laying down of calcium in bone also requires active vitamin D, and a shortage of this during childhood results in "rickets." Vitamin D is converted from its dietary to active form by sunlight, but only requires a very brief exposure. There is a balance between phosphorus and calcium in the blood: when one goes up the other goes down. People with kidney failure, on dialysis, have a difficult time clearing their blood of phosphorus, and this results in calcium being leached out of bone. Too much phosphoric acid in the diet, from soda-pop, can also weaken bone. In women, the deposition of calcium into bone requires estrogen. calcium and exercise. and if lacking these women tend to get "osteoporesis" (brittle bones) after menopause.

What is Bone Cancer?

Normally, the cells informing the bone cortex divide very rapidly from womb life through puberty, and then slow down dramatically during adult life. The major growth occurs at the ends of the long bones, called the "epiphysis": where initially new cartilage grows: this is gradually calcified by osteoblasts into hard bone. If the "epiphyseal plate" is damaged in childhood, by injury or medication, this will stunt that bone's growth. The long shaft of a bone is called the "diaphysis', and the area between the epiphysis and diaphysis is called the "metaphysis." These areas are important to know since particular bone tumors have a predilection to arise in particular areas of the bone, as will be seen. The cells inside the bone marrow, which form the blood cells, must continue to divide very rapidly throughout life, since white blood cells may normally live as little as 10 hours. The types of cancer that arise from these are lymphomas, leukemias, and myelomas, are are NOT considered primary bone cancer; they are different topics.

The control of new bone formation is by the "genes," sequences of DNA which are themselves packed into larger chromosomes in each cell. If there is damage to the genes. a given cell may start dividing out of control. Bone cancer starts in just one cell. This cell starts dividing in a haphazard manner, eventually forming a clump called a "tumor." A tumor simply means a swelling; it can be caused by infection or cancer or injury. If a tumor only grows in it's local area, and does not have the capacity to spread distantly, it is called "benign" and is not cancer. If, however, a tumor has the capability to spread distantly to other organs, it is called "malignant" and this is cancer. The actual process of cancer spread is called "metastasis," and may occur to any place in the body. Sometimes, a tumor in bone may start as benign, but further DNA damage can cause it to become malignant; this process is called "malignant degeneration." Cancer kills by anemia. infection and debility, and by spreading to and interfering with the function of critical body areas, such as the lung and brain. Any cancer that is not successfully treated will eventually lead to the patient's demise, but this may be a very rapid (weeks) or very slow (many years) process. Also, for bone some tumors have a varying degree of aggressiveness, and the same type of tumor (i.e. Giant Cell Tumor) may range from indolent to aggressive in different patients. Thus, even true bone cancers may be classed as merely "bone tumors," which doesn't say if it is a true cancer or not. Ar, essential of the evaluation is to try to detemine how aggressive. or "malignant," the tumor is.

It is important to note that this transcript discusses PRIMARY bone cancers, which means those that arise in the cortex of the bone. Cancers originating in other areas may have a strong predilection to spread to bone. such as prostate, lung and breast cancer. The treatment for these when they have metastasized to bone is discussed under the transcripts dealing with those particular cancers. Also, some cancers arise from cells which normally live in bone, such as lymphomas, myelomas, plasmacytomas. and leukemias from the blood cells within the bone marrow. These are also discussed in their own transcripts, as they are not primary bone cancers.

How Common Is Bone Cancer?

There are about 500 new cases of primary bone cancer each year in the U.S.A, making this a rare cancer. Bone cancers represent 3% of childhood cancers with about 200 new cases per year. The majority of cases are in the second decade (during adolescence), but there is a second peak in the 6th decade. About 3 per 100.000 people will ever develop a primary bone cancer. In children under 10 years old, only 20% of bone tumors are malignant. However, in adults malignant bone tumors are twice as common as benign bone tumors. Recall that most malignant tumors found in bone have spread there from another organ, and so are not primary bone cancer.

What are the Common Types of Bone Cancer?

If multiple myetoma is considered a primary bone tumor (even though it arises in the marrow and not the cortex) then it represents 40% of bone tumors. Classically, the major common types of bone cancer are "Chondrosarcoma" (arising from cartilage), "Osteosarcoma" (arising from bone), "Fibrosarcoma" (arising from scar tissue), "Liposarcoma" (arising from fat), "Ewing's Sarcoma" (from primitive cells) and the increasingly popular "Malignant Fibrous Histiocytoma" (MFH) of disputed origin. Rare types exist, like "Hemangiopericytoma" from blood vessels within the bone, "Malignant Giant Cell Tumor," and "Adamantinoma" (from enamel in teeth). It is important to note that sub-varieties of the above types exist, and there may be a mixture of elements in a given tumor. Primary examples of this are "osteochandrosarcoma" which is made of up both bone and cartilage, and 'fibrochondrosarcoma" made up of both fibrous tissue and cartilage. Another crucial thing to know is that there has been a gradual "reclassification" of bone cancers, so that MFH, which was once a rare diagnosis, is now the most common in many series! Also. various pathologists (doctors who make diagnosis from tissue samples) may give different diagnosis from examining the same bone tumor under the microscope! In fact. there is as much as a 20% disagreement by even expert pathologists when classifying biopsies (samples) of bone tumors from the same patient.

While most cancer in bone is from spread of other cancers there (such as lung or breast cancer) certain patients get "primary bone cancer". This means the cancer actually originates in the bone. Historically the treatment of these cancers was drastic amputation of a limb or other major operation to remove the bone. Unfortunately, patients often died anyway. However, newer research has shown more effective treatment for bone cancers; patients today are often cured while keeping their limb.

It is crucial to be educated and make the proper treatment choices for bone cancer. This can make the difference between keeping or loosing the limb, or life and death. It is important to have the peace-of-mind of knowing you have done everything possible to fight this cancer successfully.

Unfortunately, bone cancer is a very serious form of cancer. While not as common as breast cancer, bone cancer is nonetheless a serious condition, and those who suffer should seek some health information from their physicians.

CancerAnswers's materials explain, in plain English, the definition, types, frequency, symptoms, evaluation, historical treatment and results, and latest effective treatments and results for bone cancer. We describe surgery, radiation and chemotherapy and tell you their results. We tell you everything you need to know to help you make the right decisions today for a bone cancer problem.

This is just an excerpt of CancerAnswers's report on Bone Cancers. Much more, including latest can be sent to you by mail when you order the complete Bone Cancers transcript at a nominal cost. Thank you for using CancerAnswers as your information resource.