Soft Tissue Sarcoma

Patients with sarcoma will usually present with a non-tender mass in the limbs or in the torso. Sarcomas may affect nerve structures by compression and cause peripheral neurologic signs like radiculopathies and neuritis. Joints and bursae may also be invaded causing signs of limited mobility and pain. Cystic soft tissue tumors may transilluminate light sources during physical examinations. Late stage sarcomas can involve regional lymph nodes and cause node enlargement and adenopathies. Deep tissue masses should be accurately measured, masses more than 7 centimeters are most likely malignant in most cases of deep tissue sarcomas. Although 30% of subcutaneous soft tissue sarcomas behave less aggressively [5].

The following work-up diagnostic techniques and tests are done in patients suspected of having sarcomas:

• Imaging: In general, imaging studies like computed tomography (CT) and magnetic resonance imaging (MRI) can define the anatomic location, the extent of invasion, and the neighboring structures involved [6]. CT scan is superior in determining the number of pulmonary metastasis and identifying soft tissue tumors in the retroperitoneal space. MRI is able to define contiguous planes in sarcoma and the adjacent anatomic structures that are involved [7].
• Histopathology: The use of fine needle aspiration biopsy in the pathologic identification of sarcoma has been a standard in the diagnosis of soft tissue sarcomas. Histocytologic evaluation and immunocytochemical evaluation of the aberrant cells may be performed on multiple passes under electron microscopy as a confirmatory test [8].

Soft tissue sarcoma under intermediate to high grade classification will benefit significantly with chemotherapy using doxorubicin and ifosfamide by increasing the average survival rate of patients [9]. Localized sarcoma are treated with excision with or without chemotherapy and radiation therapy to prevent recurrence. The radical excision with amputation approach to sarcomas in the extremities affords the lowest recurrence rate among the other surgical approaches used [10]. Non-extremity sarcoma may not be easily accessible for surgical excision especially those tumors within the retroperitoneal space and the mediastinum. These cancers are treated with a combination of surgical resection, chemotherapy, and high dose radiation therapy to avert the high recurrence rating of this kinds of sarcoma.

Sarcomas are graded accordingly in reference to its cellular and subcellular structures found in the tumor. Low-grade tumors carry a good prognosis especially after surgical resection of the sarcoma. However, intermediate grade and high-grade sarcoma offer a grim prognosis despite the treatment combination of surgery and radiotherapy [4]. High-grade tumors are likely to metastasize with high morbidity rating compared to its low-grade counterparts. Osteosarcoma has a survival rating of up to 70% with chemotherapy and only 20% without chemotherapy.

There are compelling evidences that the occurrence of sarcoma is largely influenced by genetic factors like gene mutations. There are other genetic factors that increase the likelihood of the development of sarcoma like the tumor suppressor gene, unique cytogenetic defects, and various oncogenes. The development of fibrosarcoma among patients exposed to radiation therapy has placed radiation exposure as an etiologic factor in the carcinogenesis of sarcoma. Environmental carcinogens like arsenic, thorium, and vinyl chloride have been implicated in the prevalence of hepatic angiosarcoma. The advertent exposure to Epstein Barr virus and Herpes virus type 8 has been linked to the development of soft tissue tumors like Kaposi sarcoma among immunocompromised hosts.

The current incidence of soft tissue sarcoma worldwide reaches up to 35 cases per 1 million population. In the United State, sarcoma has an annual incidence rate of only 15,000 newly diagnosed cases per year [1]. The prevalence rate of sarcoma varies directly with the age of the patient. Soft tissue sarcomas occur twice as often as the primary bone sarcomas. Up to 45% of sarcoma occur in the lower extremities while visceral sarcoma is the most uncommon. Soft tissue sarcomas follow a distinct age distribution pattern like rhabdomyosarcoma that predominates among young children, the synovial sarcoma mostly occurs among young adults, and the malignant fibrous histiocytoma and liposarcoma abound among the elderly age group. Sarcomas have a slight predilection for males than in females.

The majority of soft tissue sarcomas are confined within fascial boundaries and grow centripetally (from lateral to central). These fascial boundaries are only violated during the later stages of cancer. The nearby neurovascular structures in sarcoma are displaced by the neoplasm to sides rather than enveloped as with other invasive cancers. The compressed fibrous region is surgically referred to as the compression zone while the thin layer surrounding this zone is called the reactive zone. These layers will guide surgeons on where to resect the tumor during an en bloc tumor removal or debulking operations.

A sarcoma tumor that has been removed with its capsule will leave behind microscopic tumor particles that usually recure in the same location in 80% of cases within 2 to 3 years from initial operation [2]. The radical use of radiation therapy after surgical resection drastically reduce the incidence of recurrence after tumor removal. High grade and intermediate grade sarcomas are likely to metastasize through the blood and seed in the lungs in the majority of cases. Lung metastasis among high-grade sarcomas occurs in 53% of cases [3].

The prudent avoidance of environmental carcinogens like arsenic, vinyl chloride, and radiation therapy may prevent some soft tissue sarcoma from occurring. The early detection and prompt intervention of sarcoma with excision surgery and adjuvant chemotherapy and radiotherapy can prevent high-grade sarcomas from metastasizing to distant organs.

Soft tissue sarcoma is a clinical term that refers to a broad group of cancers that affect soft connective tissues. Treatment approaches to sarcoma varies on the tumor type, anatomic location, and other patient factors. Sarcoma is conveniently divided into two types based on cell type and includes liposarcoma, leiomyosarcoma, and rhabdomyosarcoma.

Definition

Soft tissue sarcoma is a group of rare cancers that affect the soft tissues that support, surround, and connect organs.

Cause

Genetic mutation is implicated in the development of most sarcomas. Exposure to environmental toxins like vinyl chloride, thorium dioxide, and arsenic are among the popular etiologic agents of the neoplasm. Post-radiation exposure sarcoma has been documented in some patients.

Symptoms

The presence of a non-tender mass tissue in the torso or the extremities. Compression signs are common on the neurovascular structures adjacent to the primary tumor growth.

Diagnosis

A complete physical examination is done to diagnose sarcoma. Imaging studies and histopathologic studies (biopsy) are known confirmatory tests for the diagnosis.

Treatment and follow-up

Surgical excision, adjuvant chemotherapy, and radiotherapy are the therapeutic modalities available for the treatment of sarcoma.

1. Borden EC, Baker LH, Bell RS, et al. Soft tissue sarcomas of adults: state of the translational science. Clin Cancer Res. 2003 9 (6): 1941–56.
2. Enneking WF. Staging of musculoskeletal neoplasms. In: Uhthoff HK, ed. Current Concepts of Diagnosis and Treatment of Bone and Soft Tissue Tumors. Heidelberg:. Springer-Verlag; 1984.
3. Potter DA, Glenn J, Kinsella T. Patterns of recurrence in patients with high-grade soft-tissue sarcomas. J Clin Oncol. Mar 1985; 3(3):353-66.
4. Longhi A, Errani C, De Paolis M, Mercuri M, Bacci G. Primary bone osteosarcoma in the pediatric age: state of the art. Cancer Treat Rev. 32 (6): 423–36.
5. Gustafson P. Soft tissue sarcoma. Epidemiology and prognosis in 508 patients. Acta Orthop Scand Suppl. Jun 1994; 259:1-31.
6. Gay F, Pierucci F, Zimmerman V, Lecocq-Teixeira S, Teixeira P, Baumann C, et al. Contrast-enhanced ultrasonography of peripheral soft-tissue tumors: Feasibility study and preliminary results. Diagn Interv Imaging. Jan 2012; 93(1):37-46.
7. Bland KI, McCoy DM, Kinard RE. Application of magnetic resonance imaging and computerized tomography as an adjunct to the surgical management of soft tissue sarcomas. Ann Surg. May 1987; 205(5):473-81.
8. Dal Cin P. Soft tissue tumors: an overview. Atlas Genet Cytogenet Oncol Haematol. January 2003.
9. Casper ES, Gaynor JJ, Harrison LB. Preoperative and postoperative adjuvant combination chemotherapy for adults with high grade soft tissue sarcoma. Cancer. Mar 15 1994; 73(6):1644-51.
10. Geer RJ, Woodruff J, Casper ES. Management of small soft-tissue sarcoma of the extremity in adults. Arch Surg. Nov 1992; 127(11):1285-9.