A risk factor is anything that may increase your chance of having a disease. Risk factors for a certain type of cancer might include smoking, diet, family history, or many other things. The exact cause of someone's cancer may not be known. But risk factors can make it more likely for a person to have cancer.

Things you should know about risk factors for cancer:

• Risk factors can increase a person's risk. They do not necessarily cause the disease.
• Some people with risk factors never develop cancer. Other people can develop cancer and have few or no risk factors.
• Some risk factors are very well known. But there is ongoing research about risk factors for many types of cancer.

Some risk factors, such as family history, aren't in your control. Others may be things you can change. Knowing the risk factors can help you make choices that might lower your risk. For example, if an unhealthy diet is a risk factor, you may choose to eat healthy foods. If being at a higher weight is a risk factor, you may decide to try to lose weight.

Anyone can get soft tissue sarcoma. Most people who get soft tissue sarcomas don't have any known risk factors. But there are some factors that can raise your risk for this cancer. These can include:

• Exposure to radiation. People who have had past radiation therapy to treat other cancers, such as breast or cervical cancer, have a slightly higher risk for soft tissue sarcoma. This would occur in the place where the radiation was focused.
• Certain inherited syndromes. People who inherit certain genetic syndromes from a parent are more likely to get soft tissue sarcomas. These include neurofibromatosis type 1, Li-Fraumeni syndrome, hereditary retinoblastoma, Werner syndrome, Gardner syndrome, familial adenomatous polyposis, Gorlin syndrome, and tuberous sclerosis.
• Exposure to certain other chemicals (especially in the workplace). Exposure to high levels of certain chemicals in the workplace, such as phenoxy herbicides, may raise the risk of soft tissue sarcomas.
• Lymph system damage (lymphedema). Lymphedema is where fluid collects in the tissue and causes swelling. People who have chronic lymphedema caused by radiation to lymph nodes or surgical removal of lymph nodes have a slightly higher risk for soft tissue sarcoma. This would occur in the area where lymphedema was present.
• Infection with human herpesvirus 8 (HHV-8) and HIV. People infected with these viruses have an increased risk for a specific sarcoma called Kaposi sarcoma.

Because most people who get soft tissue sarcoma may not have any risk factors, doctors have little advice on how to prevent this cancer. Talk to your doctor if you're worried about your risk.

When possible, you should stay away from these risk factors:

• Limit exposure to radiation. This may not be possible for people who need radiation therapy to treat cancer.
• Limit exposure to certain chemicals, especially herbicides.

You may be at a higher risk for this type of cancer if you or anyone in your family has certain conditions or inherited syndromes like those listed above. Some of the inherited syndromes include neurofibromatosis type 1, Li-Fraumeni syndrome, Gardener syndrome, and hereditary retinoblastoma. Ask your doctor if you should be tested for inherited genes that might increase your risk of soft tissue sarcoma.

There are no specific tests to screen for sarcoma before it causes symptoms. You have a better chance of surviving soft tissue sarcoma if it's found and treated early. For this reason, tell your doctor right away if you have any lumps or swelling on your body. Also tell your doctor if a lump is causing pain or if it doesn't go away or is getting larger. Even though most lumps aren't sarcomas, it's important to have a lump checked. Your doctor may watch the lump or have tests done.