A risk factor is anything that changes your chance of getting a disease such as cancer. Different cancers have different risk factors. For example, unprotected exposure to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for cancers of the lung, and many other cancers. But risk factors don't tell us everything. Having a risk factor, or even several, doesn't mean that you will get the cancer. Also, many people get cancer without having a risk factor.

Scientists have found a few risk factors that make a person more likely to develop soft tissue sarcomas.

Radiation exposure

Patients may develop sarcomas from radiation given to treat other cancers, such as breast cancer or lymphoma. The sarcoma often develops in the area of the body that had been treated with radiation. The average time between radiation exposure and diagnosis of a sarcoma is about 10 years. Radiation exposure accounts for only a small percentage of sarcomas (less than 5%).

Radiation therapy techniques have improved steadily over several decades. Treatments now target the cancers more precisely, and more is known about selecting radiation doses. These advances are expected to reduce the number of cancers caused by radiation therapy. But because these cancers take so long to develop, the results of these changes may not be seen for a long time. Still, radiation therapy is used only when its benefits (improved survival rate and relief of symptoms) outweigh the risk of cancer and other complications. For more information, see our document Second Cancers Caused by Cancer Treatment.

Genetic syndromes

Certain inherited conditions increase a person's risk of developing soft tissue sarcomas.

• Neurofibromatosis is a disease that usually runs in families and is characterized by many neurofibromas (benign tumors that form in nerves under the skin and in other parts of the body). It is also known as von Recklinghausen disease. It is caused by a defect (mutation) in a gene called NF1. About 5% of people with neurofibromatosis will develop a malignant peripheral nerve sheath tumor in a neurofibroma.

• Gardner syndrome is a disease caused by defects in the gene APC. People with this syndrome get many polyps in the colon (and intestines) and have a high risk of getting colon cancer. It also causes musculoaponeurotic fibromatosis (also called desmoid tumors). Some experts consider desmoid tumors to be a slow-growing (low-grade) type of fibrosarcoma.

• Li-Fraumeni syndrome is caused by inherited defects in the gene TP53. People affected by this syndrome have a high risk of cancer, such as breast cancer, brain tumors, and sarcomas. People with this syndrome are sensitive to the cancer-causing effects of radiation - if their cancer is treated with radiation, they have a very high chance of developing a new cancer in the part of the body that received the radiation.

• Retinoblastoma is an eye cancer of children that can be caused by inherited defects in the gene Rb-1. Children with the inherited form of retinoblastoma also have an increased risk of developing bone or soft tissue sarcomas.

• Werner syndrome is caused by defects in the gene RECQL2. Children with this syndrome have problems like those seen in the elderly. These include clogged heart arteries (arteriosclerosis) which can lead to heart attacks, cataracts, and skin changes. They also have an increased risk of cancer, including soft tissue sarcomas.

• Gorlin syndrome, also called nevoid basal cell carcinoma syndrome, is caused by defects in the PTC gene. People with this syndrome have a high risk of developing many basal cell skin cancers. They also have an increased risk of getting fibrosarcoma and rhabdomyosarcoma.

• Tuberous sclerosis can be caused by a defect in the TSC1 gene. It can also be caused by a defect in another gene: TSC2. People with this syndrome often have seizures and learning problems. They get benign tumors in many different organs. They also get kidney problems, often along with a kidney tumor called angiomyolipoma. People with tuberous sclerosis have an increased risk of getting rhabdomyosarcoma.

Damaged lymph system

Lymph is a clear fluid containing immune system cells that is transported throughout the body by a series of lymph vessels. These vessels connect lymph nodes (small bean-shaped collections of immune system cells). When lymph nodes have been removed by surgery or damaged by radiation therapy, lymph fluid can build up. This is called lymphedema. In other parts of the world, severe lymphedema (a condition called elephantiasis) is sometimes caused by infection with a parasite that blocks lymph vessels. Lymphangiosarcoma is a very rare complication of chronic lymphedema.

Chemicals

Exposure to vinyl chloride (a chemical used in making plastics) is a risk factor for developing sarcomas of the liver, but it has not been proven to cause soft tissue sarcomas. Exposure to dioxin and to herbicides that contain phenoxyacetic acid at high doses (farm workers work closely with these chemicals) may also be risk factors, but this is not known for certain. There is no evidence that herbicides (weed killers) or insecticides, at levels encountered by the general public, cause sarcomas.

Injury

An injury is not a risk factor for developing sarcomas. However, this issue has caused some confusion in the past. One reason is that injury may produce a swelling that resembles a tumor but is not a true tumor. Also, when you are injured, the pain may draw your attention to the injured area. The area may be examined closely, and x-rays or other imaging studies may be obtained. This can make it more likely that any sarcoma that is present will be discovered, even though it may have been present for some time.

Last Medical Review: 03/03/2009
Last Revised: 05/14/2009