Risks of Getting a Sarcoma

What Causes, or Increases the Risk of Getting a Sarcoma - a malignant (cancerous) tumor of the soft tissues?

The common underlying factor is damage to DNA which causes the affected cell to become transformed - that is lose control over it’s division. Cancer is ultimately a disease of the DNA!

Things which seem to increase overall sarcoma risk:

Carcinogens (Chemical Exposure)

Radiation Exposure

Viruses

Genetic Diseases

Chronic Irritation

Can sarcomas be prevented?
There is no sure way to prevent any sarcoma. It is always a good idea to avoid unnecessary exposure to potential carcinogens and avoid unwarranted X-rays. This is especially true for people with family susceptibility to cancers, or who actually have genetic diseases. If a worrisome sign or symptom arises (see below) it should be evaluated promptly, and not ascribed to some benign process without proof. Eating a diet with enough vitamin C (Ascorbic Acid) is important for proper maintenance and healing of soft tissues, especially cartilage. Vitamin C deficiency results in a breakdown of the soft tissues (scurvy); it is essential for crosslinking their crucial collagen proteins. However, taking too much can cause the blood to become too acidic (ascorbic acidemia). A standard supplement multi-vitamin is well advised.

Understanding Cancer:
What Are the Normal Soft Tissues?

The human body is made up of individual cells, of which there are various kinds. Initially, when the father’s sperm and mother’s egg join to form a fertilized egg, each cell in the human embryo is exactly the same. As the embryo’s cells divide, the genetic material within them, called DNA, instructs certain cells to specialize - that is become lung cells, heart cells, bone cells, brain cells, etc.. This process of specialization is called differentiation, and accounts for the wide variety of cells making up us adults. The early embryo separates cells into 3 basic distinctions - cells for making skin, brain and the nerves (ectoderm), cells for making the organs (endoderm), and cells cells for making bone, flesh and blood (mesoderm). However, ultimately the mesoderm cells are found in all parts of a human beeing.

Certain specialized cells are programed to form tissues, which are a collection of cells for a certain purpose. Examples of tissues include skin, muscle, fat, bone, blood and cartilage. The tissues are joined in complex patterns to form organs, which contain many types of cells. For instance, the ear is an organ which contains bone (the ossicles), muscle fibers, nerves, fat, cartilage and skin, all precisely organized. Organs are further arranged into organ systems. The ear must be properly connected to another organ, the brain, to function. Other examples of organ systems include the skeletal, digestive, urinary, and reproductive systems. Still, as complex as the systems become, they still are made of single cells as the smallest unit of life.

The mature human body contains organs, bones, flesh, and blood, and each of these complex structures are formed from simpler tissues. The soft tissues of the body are basically it’s flesh - formed of muscles, fat, cartilage, and fibrous tissues. These tissues are not only found as the middle layer (mesoderm) between the skin and bone, but are also a part of many internal organs, such as the stomach, bladder, uterus, and bone. Thus, a disease of the soft tissues can actually arise almost anywhere in the body! This is because these basic tissues are the building blocks of nearly all a human’s parts. While the bone is initially from the mesoderm flesh (it starts out as cartilage), as it becomes calcified it is no longer considered a soft tissue (after all it is hard!). Thus, diseases, including cancer, of bone are classified separately from soft tissue diseases, even though the same tissues may be involved. Skin is also classified separately since it arises from a different area of the developing embyro (ectoderm), along with the nerves and brain.

Thus, the basic soft tissues making flesh in the adult are the muscle, fat, fibrous tissues (sinews), cartilage, and blood vessles.

To understand disease of these, we must look at them on their cellular level. There are actually three types of muscle cells in the body, several types of fibrous cell, but only one type of fat and cartilage cell. The blood vessles are made up of layers of various types of cells. For muscle cells, there are intercalated heart cells, striated skeletal muscle cells, and smooth organ muscle cells. The diseases from them are named in Latin:

Chondro - means arising from cartilage cells. In a growing bone, the cells lay down cartilage which is formed of various condroitin proteins. These proteins are also called "glucose-amino-glycans" or "GAGs"; they are made of chains of amino acids linked by sugars. Later, the cartilage can become calcified to form hard bone, but other areas (ears, nose, joints, ribs) will contain cartilage throughout adult life. Cartilage is nourished by diffusion of tissue fluid.

Rhabdomyo - means arising from the striated, or skeletal muscle. This type of muscle shows a small patterns of bands (striations) under the light microscope, and is under voluntary control - the muscles we can move such as in the face and limbs. Muscles often have specific vessels that feed them.

Leiomyo - means arising from the smooth muscles. This type of muscle occurs as linings within organs, arranged in circular or longitudinal patterns. It is not under voluntary control, but instead controlled by the autonomic nervous system - by the body itself. Examples of this kind of muscle are contracting linings of the intestines, uterus, and blood vessels.

Lipo - means arising from fat cells, called adipocytes. These fat cells are found in all sorts of body areas, including behind the eyeballs, within the bone marrow and in the liver. Most fat cells are in the trunk and limbs.

Fibro - means arising from the fibrous tissues (sinews) of the body, and in particular the fibroblasts which are the basic scar tissue of the body.

Synovial - a specialized type of fibrous tissue making the sacs that surround certain joints, like the knees. These cells secrete special fluid to lubricate.

Neurofibro - means arising from the linings around nerves, made up of an insulating substance called myelin (makes nerves white). The myelin is produced by Schwann cells, which line the nerves and are also considered a fibrous soft tissue. Only the nerve linings are a soft tissue.

Angio, Hemangio - means arising from the blood vessel cells. While blood is not considered a soft tissue, the blood vessels are.

Osteo - means arising from bone. Even though bone tumors are considered separately from soft tissue tumors, the bone is a mesenchymal (middle layer) tissue and may be found mixed into other soft tissue tumors.

Meso or Myxo - this means arising from a mixture of soft tissues, which may be blood vessels, cartilage, fat, fibrous tissues, and smooth or striated muscle. It is related to Mesothelium (middle layer) also called Mesenchymal.

That is the range of crucial soft tissues in the body, and understanding the above prefixes allows us to categorize the diseases that arise from these mesechymal cells. It is not uncommon for more that one type of cell to be involved with a disease process, so sometimes the names are conjoined together to describe the cells seen under the microscope. Examples include Chondrofibro, Osteochondro and Lipofibro; they are all mesenchymal (middle embryo layer) diseases.

How Common is Soft Tissue Sarcoma?
Each year about 8,000 new cases of Soft Tissue Sarcoma are reported in the United States: They cause approximately 2,500 deaths per year. Thus, they represent ~1% of all new cancers. Soft Tissue Sarcoma is about 3 times more common than Bone Sarcoma. There are two peaks of most common patient age, one in childhood at 10 years old and the other in 40 year old adults. Thus Sarcomas are unlike the other major type of cancer, Carcinomas (e.g. breast, lung, prostate, colo-rectal) which all tend to get more likely as we age. Males and Females are overall equally affected by Sarcomas. In children, the most common type of Soft Tissue Sarcoma is Rhabdomyosarcoma (from skeletal muscle cells), which occur mostly in the Head and Neck areas. In contrast to childhood cases, the least common area for adult sarcomas is in the Head and Neck area. In adults, the most common type is now Fibrosarcoma or the closely related Malignant Fibrous Histiocytoma, which tends to occur in the trunk or extremities. These account for up to 80% of soft-tissue sarcoma cases. "Chondrosarcoma" is the second most common sarcoma, with about 500 cases per year in the USA. Overall, the number of new cases of Soft Tissue Sarcoma has remained stable for the past 3 decades.

What Causes, or Increases the Risk for Getting a Sarcoma?
As with every cancer, the precise reason why one person gets a Sarcoma and another does not remains unknown. This is particularly true for Chondrosarcoma, which often arises with no preceding risks identified. However, depending upon the particular subtype, various things have been noted which seem to increase overall sarcoma risk:

1) Carcinogens (Chemical Exposure) - Some chemicals have the ability to get into cells and damage their DNA, leading to disease. The chemical may kill cells, leading to an increase in production of new ones, but some cells may not be killed only injured. These cells often try hard to repair themselves, but may try to divide before succeeding with complete repair. The more often damaged cells try to divide, the higher the chance for a cancer to arise. Some chemicals shown to raise the risk for cancer in general, and sarcomas in particular, include Dioxin, Polyvinyl Chloride, Arsenic, Benzene, and Thorium.

2) Radiation Exposure - Ionizing radiation passes through cells and damages their DNA. This may lead to malfunction of genes which would normally prevent the damaged cell from dividing (suppressor gene), or turn on a potential cancer gene (oncogene). The most common type of cancers arising from prior radiation treatment are sarcomas.

While the risk is extremely low with occasional diagnostic X-rays, getting X-ray therapy (especially for a cancer caused by a genetic disease {e.g. retinoblastoma} may result in a 20% risk of later sarcomas (radiation carcinogenesis).

3) Viruses - These actually get into cells, insinuate themselves into the DNA, and start giving their own instructions to the cell! In the process, they can do damage to the host DNA, leading to cancer. Kaposi’s sarcoma linked with the HIV (AIDS) virus is the best known example.

4) Genetic Diseases (Family Syndromes) - These include disease where the genes are damaged from birth, and thus susceptible to turning cancerous (such as Neurofibromatosis, Beckwith Weidemann and Retinoblastoma). Also, there are inborn diseases where DNA repair is impaired, or the stop signal that prevents damaged cells from dividing is broken (Li-Fraumeni). With Chondrosarcoma, there may be preceding Enchondromas (bone cysts) from the rare Maffucci's syndrome or Ollier's syndrome.

5) Chronic Irritation - This can stimulate cells to divide, and the more often division occurs (especially in cells that don’t normally divide often) the more likely a cancerous one is to arise. Examples include the lymphangiosarcomas seen in limbs with chronic swelling (edema) called the Stewart-Treves syndrome in women with arm swelling after treatment for breast cancer. Also, there is more risk for sarcomas around permanent stabilization pins placed into bones and joints after traumatic injuries.

The common underlying factor is damage to DNA which causes the affected cell to become transformed - that is lose control over it’s division. Cancer is ultimately a disease of the DNA! The DNA is packed into thousands of genes, which are themselves located upon the 48 chromosomes (46 general plus 2 sex chromosomes) that all healthy humans have in every cell. The chromosomes become visible under an ordinary light microscope when cells divide, and nearly every case of Sarcoma shows chromosome damage. This damage usually includes pieces missing from chromosomes (deletions), or even parts of one chromosome getting stuck onto another (translocations). Overall, anything which can damage DNA, the fundamental genetic material, will increase the risk of a cell turning cancerous. This damage may be latent, meaning a cancer may arise many years or decades after the damage occurs.