
Soft tissue sarcoma (STS) accounts for approximately 1% of all cancers diagnosed annually in the United States. Population-based data from Connecticut covering the years 1935-1989 have shown an increasing incidence of STS in both genders, with a greater increase among men than women. The recent increase in acquired immune deficiency syndrome-related Kaposi's sarcoma does not explain the upward trend in STS, dating back decades.   Excluding Kaposi's sarcoma, the incidence of soft tissue sarcoma has remained stable in Europe (3-4/100,000)

&&url PMID: 9344316
&&url PMID: 11688207
&&url PMID: 11441293

Soft tissue sarcomas are difficult to diagnose.
So one would expect there might be some fuzziness in sarcoma statistics, if there are some diagnostic difficulties.
&&url PMID: 1932225 

There are many different causes [etiologies] of sarcoma, which are reflected in the variations of sarcomas in site and cell type.  Not all LMS risk factors are listed directly below, some are listed in the separate section they belong to, further down on this page.
 
Among the environmental exposures associated with STS are:

external radiation therapy (prevalence of radiation-induced sarcoma: 0.17-0.21%), 
Thorotrast [a contrast Xray dye no longer used], 
arsenical pesticides and medications, 
chlorophenols,
phenoxy herbicides, 
dioxin, 
vinyl chloride, 
immunosuppressive drugs, 
alkylating agents, 
androgen-anabolic steroids, 
human immunodeficiency virus, 
human herpes virus type 8 [Kaposi's sarcoma]
chronically edematous arms after radical mastectomy for breast cancer (Stewart-Treves syndrome)

&&url PMID: 11441293
&&url PMID: 11688207
&&url PMID: 9344316
&&url PMID: 14533826

Partly because of sarcoma rarity, scant attention has been given to their hereditary etiology.  In one study the authors selected 10 sarcoma-prone families ... and focused on them.  
These families displayed marked heterogeneity. In one of these families, 16 relatives had sarcomas, with 2 of the 16 each having 2 metachronous [at the same time] sarcomas; to our knowledge, this represents the greatest number of sarcomas reported in any family described to date. Two familial atypical multiple-mole melanoma syndrome kindreds with the CDKN2A mutation showed the association of sarcoma with malignant melanoma, whereas one family had several pancreatic carcinomas.  Other families with sarcoma had hereditary nonpolyposis colorectal carcinoma with MSH2 mutation, hereditary breast carcinoma with BRCA1 mutation, and p53 mutation in a Li-Fraumeni syndrome.
&&url PMID: 14584079 

In addition, STS occurs excessively among persons with certain other heritable states.  See the section on Hereditary LMS.. 
New syndromes are being discovered as the human genome is being interpreted.  
Some cases of severe immunodeficiency [AIDS, transplant patients] show Epstein-Barr virus is sometimes implicated in LMS.
Sarcomas, including LMS, are associated with autoimmune thyroid disease, and associated with other autoimmune illnesses.
In some cases the genetic predisposition may have interacted with environmental determinants to produce particular tumors.
&&url PMID: 281540
&&url PMID: 11441293
&&url PMID: 11688207
&&url PMID: 9344316 

Causes of sarcomas and leiomyosarcomas also include:
Post transplant immunosuppression. 
thyroid disorders
autoimmune disease
cyclophosphamide
hormonal factors [especially estrogen]
chronic repair processes

&&url PMID: 11441293
&&url PMID: 14599743
&&url PMID: 14533826


These risk factors provide leads for further investigations into the genetic and environmental determinants of various forms of STS.   Cancer is a genetic disease in which many factors including diet, smoking, chemicals, sunlight, hereditary factors, and viruses  are thought to cause alterations or mutations in our genes. An alteration can result in a change of the DNA material within a gene or in excessive copies of a gene.  When enough mutations accumulate, the normal processes inside the cell go awry, and tumors begin to grow. 

It is quite clear that there are certain situations which cause certain damage which can result in LMS.
Why don't all the people who CAN get a cancer get it? 

It's chance.   It depends upon what the radiation photon, the virus, the antibody, actually attacks.  Since most of the causal agents cause DNA damage, the sum of the exposures IS additive.   

Much of the damage comes from free radicals.  Antioxidants help prevent free radicals.  So one way that people predisposed to cancer DON'T get the cancer, is lots of antioxidants in their foods.  This has been illustrated with the epidemiological investigation of green tea drinkers and cancer incidence rates.

For exposure to be significant, it is usually noticeable.  The one person I know who was exposed to that wood preservative, painted her deck and practically bathed in it.  People who have had radiation therapy, or significant exposure to radiation know about it, usually.  Cyclosphosphamide does not grow freely under trees.

Autoimmune disease, especially thyroid, seems to predispose to malignancy.  Autoimmune disease relapses can be stress related.  If there is less stress, there will be fewer autoimmune active spells, and fewer antibodies, and less chance of getting p53 DNA damage.  Autoimmune disease itself probably develops from a combination of genetric susceptibility and possibly a viral trigger.  

About smoking-- there was one study done that showed DNA repair took longer in cells of people who smoke.

In the words of a friend, it's mostly a crapshoot.  BUT it is not completely a crapshoot.  There are predisposing factors, and there are things you can do to counteract those factors...
&&url
&&url
