A risk factor is anything that increases your chance of getting a disease such as of cancer. Risk factors can be lifestyle-related, environmental, or inherited. Different cancers have different risk factors. For example, unprotected exposure to strong sunlight is a risk factor for skin cancer and smoking is a risk factor for cancers of the lung, larynx, mouth, throat, esophagus, kidneys, bladder, and several other organs.

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

Ionizing radiation: This risk factor accounts for only a small percentage of sarcomas (less than 5%). The most common cause of radiation exposure in patients who develop sarcomas is from radiation given to treat other tumors, such as breast cancer or lymphoma. The average time between radiation exposure and diagnosis of a sarcoma is about 10 years.

Radiation therapy techniques have steadily 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 secondary cancers resulting from radiation therapy. However, oncologists (doctors with special training in the diagnosis and treatment of cancer) prescribe radiation therapy only when its benefits (improved survival rate and relief of symptoms) outweigh the risk of this and other complications.

Family history: 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). One or more neurofibromas will develop into a malignant peripheral nerve sheath tumor in about 5% of people with neurofibromatosis.

• Gardner syndrome is a disease that runs in families and leads to benign polyps (precancerous growths) and cancers in the intestines. It also causes desmoid tumors (a type of low-grade fibrosarcoma) in the abdomen and benign bone tumors.

• Li-Fraumeni syndrome runs in families and increases the risk of developing breast cancer, brain tumors, leukemias, and cancer of the adrenal glands. People with Li-Fraumeni syndrome also have an increased risk of developing soft tissue sarcomas and bone sarcomas. 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 hereditary. Children with the inherited form of retinoblastoma also have an increased risk of developing bone or soft tissue sarcomas.

Damaged lymph system: Lymph (a clear fluid containing immune system cells) is transported throughout the body by lymph vessels and filtered by lymph nodes (small bean-shaped collections of immune system cells). Lymphangiosarcomas, a cancer of lymph vessels, can develop in parts of the body where lymph nodes have been removed by surgery or damaged by radiation therapy. Although this is a rare complication, it affects some women whose axillary lymph nodes were removed and who received radiation to treat their breast cancer.

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, pain from an injury draws a person's attention to the injured area, making it more likely that the sarcoma will be discovered, even though it had been present for some time.

Revised: 11/15/2006