What are soft tissue sarcomas
Sarcomas are a heterogeneous group of tumors that encompass three major groups: soft tissues, bones, and GIST (gastrointestinal stromal tumor).
Soft tissue sarcomas are rare tumors that originate in “soft tissues” such as muscles, bones, tendons, blood vessels, fat cells, and cartilage – and therefore can affect any part of the body.
There are about 100 subtypes of sarcomas, but they are rare and represent less than 2% of all cancers in adults. In Brazil, there are few epidemiological studies on the disease, but comparisons of regional data with international databases show that the incidence and prognosis of these tumors are similar in the country and the rest of the world.
About 50% of soft tissue sarcomas originate in the arms and legs, 40% in the trunk, and 10% in the head and neck. The digestive tract can also be affected, as well as the back of the abdomen (retroperitoneum) and the female reproductive system (gynecological sarcomas).
The causes are unknown in most patients, although a small percentage of cases are related to factors such as hereditary genetic syndromes (such as neurofibromatosis or von Recklinghausen disease, Gardner syndrome, Li-Fraumeni syndrome, retinoblastoma, Werner syndrome, Gorlin syndrome, and tuberous sclerosis), weakened immune system due to HIV infection, and exposure to radiation and chemical agents.
Subtypes of soft tissue sarcomas
The most relevant subtypes among soft tissue sarcomas are:
- Angiosarcoma – a malignant tumor that can develop from the inner lining of blood vessels (in any part of the body, but commonly in the skin, breast, liver, spleen, deep tissues). These tumors are associated with radiation exposure and may originate in areas subjected to radiation therapy to cure other diseases, such as sarcoma of soft tissue;
- Desmoplastic small round cell tumor – a rare sarcoma that occurs in teenagers and young adults. It is most commonly found in the abdomen;
- Epithelioid sarcoma – most often develops in tissues beneath the skin of the hands, forearms, feet, or legs. It is more common in teenagers and young adults;
- Liposarcomas – malignant tumors of adipose tissue (fat cells), they can develop in any part of the body but are more frequent in the thighs, below the knees, and inside the abdomen;
- Rhabdomyosarcoma – originates from cells that make up skeletal muscles. It is the most common type of soft tissue sarcoma seen in children;
- Dermatofibrosarcoma protuberans – originates in the deep layers of the skin, usually on the trunk or limbs. It grows into nearby tissues and rarely spreads to distant sites;
- Desmoid fibromatosis – a slow-growing tumor with steady growth. It rarely spreads to distant sites but has potential for local aggressiveness;
- Pleomorphic sarcoma: the most frequent subtype of sarcoma in adults. It mainly originates in the lower limbs;
- Leiomyosarcoma: begins in cells called smooth muscles, responsible for the involuntary contraction of muscles, found in organs and vessels. This means they can originate in any part of the body, with the stomach, limbs, and uterus being the most common sites;
- Gastrointestinal stromal tumor (GIST): a tumor that originates from Cajal cells, a group of cells in the wall of the gastrointestinal tract responsible for intestinal motility (signaling the muscles to move fluids and food through the gastrointestinal tract). This tumor can originate in any part of the gastrointestinal tract, from the esophagus to the anus.
Symptoms of soft tissue sarcomas
The symptoms depend on the type of soft tissue sarcoma and the affected area. Usually, the first sign is a painless lump. Tumors larger than 5 cm should be considered suspicious and evaluated by an experienced professional.
Generally, soft tissue sarcomas are asymptomatic in their early stages. As the tumor develops, there may be an increase in the volume of the affected area, as well as possible swelling and changes in local sensitivity. Pain occurs when the tumor grows and presses on nerves – in these cases, there may be difficulty in movement.
Tumors originating from the digestive tract can cause bleeding in the stool, vomiting, anemia, and abdominal pain.
Diagnosis of soft tissue sarcomas
Diagnosis of soft tissue sarcomas begins with a physical examination based on the observation of some of the symptoms. Blood tests are performed to help detect the disease, and imaging tests such as computed tomography (CT), magnetic resonance imaging (MRI), and PET-CT are important for finding the location of the tumor and assessing both the extent of local disease and whether there is spread to other parts of the body (metastases).
After the imaging analysis, the diagnosis is confirmed through a biopsy, which involves removing a piece of the tumor and analyzing it in the laboratory to confirm the subtype, degree of aggressiveness, and molecular characteristics that may aid in treatment.
Diagnosis of soft tissue sarcomas
The diagnosis of soft tissue sarcomas begins with a physical examination based on the observation of some of the symptoms. Blood tests are performed to help detect the disease, and imaging tests such as computed tomography, magnetic resonance imaging, and PET-CT are important to find the location of the tumor and assess both the extent of local disease and whether there is spread to other parts of the body (metastases).
After the imaging analysis, the diagnosis is confirmed through a biopsy, which involves the removal of a piece of the tumor and laboratory analysis to confirm the subtype, aggressiveness grade, and molecular characteristics that may help in treatment.
Treatment of soft tissue sarcomas
The low incidence, wide spectrum of subtypes, biological behaviors, and ubiquity make the management of soft tissue sarcomas challenging. Therefore, treatment should be carried out in a multidisciplinary setting, with teams of experienced specialists. Treatment depends on the type, size, and location of the tumor and may use the three most common modalities in oncology:
- Surgery;
- Radiotherapy;
- Chemotherapy.
For localized tumors – those that have not spread to other organs or tissues – surgery to remove the lesion is always recommended. Chemotherapy and radiotherapy can be used before (neoadjuvant) or after (adjuvant) surgery to increase the chance of cure or reduce the risk of recurrence (return of the tumor).
In locally advanced or metastatic sarcomas, systemic treatment is the mainstay, based on chemotherapy or targeted therapies. The choice of medications depends on the type of tumor and the patient’s clinical conditions. In some cases, radiotherapy and surgery can be used to control symptoms and metastases.
Treatment is a journey that, in addition to drugs, surgery, and radiotherapy, includes regular appointments with blood tests, imaging, and clinical evaluation by the doctor. The frequency and duration of treatment are assessed individually.
Whenever possible, the option to participate in a clinical trial should be considered. Clinical trials are important because they seek to find new treatments for cancer and test their effectiveness and safety compared to existing treatments. Patients participating in a clinical trial may receive standard treatment or be the first to use new therapeutic options, improving treatment and understanding of cancer.
Prevention of soft tissue sarcomas
Most soft tissue sarcomas have no known risk factor, which makes prevention difficult. There is no routine screening test that helps detect the disease.
For those with genetic syndromes related to the disease, regular screening tests can help in early diagnosis of these tumors and result in a greater chance of cure in treatment.
