Soft-tissue fibrosarcomas

RELATED CONDITIONS: Angiosarcoma, alveolar soft part sarcoma, clear-cell sarcoma, dermatofibrosarcoma protuberans, desmoid tumors, desmoplastic small-cell tumor, elastofibroma, epithelioid hemangioendothelioma, epithelioid sarcoma, fibroma, fibrous histiocytoma, fibromatosis, gastrointestinal stromal tumor, glomangiosarcoma, leiomyosarcoma, liposarcoma, lymphangiosarcoma, Kaposi sarcoma, musculoaponeurotic fibromatosis, neurofibrosarcoma, rhabdomyosarcoma, superficial fibromatosis, synovial sarcoma, and malignant versions of fibrous histiocytoma, granular cell tumor, hemangiopericytoma, mesenchymoma, peripheral nerve sheath tumor, and schwannoma tumors

DEFINITION: Fibrosarcomas are soft-tissue sarcomas (malignant tumors) of the fibroblasts, the cells that produce the fibrous tissues that connect, support, or surround other organs and tissues in the body (such as those around the joints). They are one of many soft-tissue sarcomas, unlike osteosarcomas that develop in the bone. Fibrosarcomas are often grouped with other soft-tissue sarcomas because these diseases share specific characteristics and have similar treatment options. Fibrosarcomas usually occur in the arms, legs, or torso area, most commonly in the legs.

Risk factors: Most soft-tissue sarcomas have no known cause. However, several factors may increase the risk of developing these types of cancer. Radiation therapy, usually for other types of cancer, is the best-documented risk factor for this disease, possibly because radiation may inactivate the lymph nodes. Surgical removal of the lymph nodes also seems to play a part in the development of this disease.

Another risk factor for this type of disease is exposure to certain chemicals, usually in the workplace. Chemicals that may cause this type of cancer are arsenic, herbicides, vinyl chloride, and wood preservatives.

This disease is also associated with certain genetic mutations. People with alterations in the FH, NF1, KIT, CDKN2A, CDKN2B, and TP53 tumor-suppressor genes, or the RB1 gene and who have the diseases associated with these genetic mutations (Li-Fraumeni syndrome and neurofibromatosis, also called von Recklinghausen disease) are much more likely to develop soft-tissue sarcomas, including fibrosarcoma.

Other diseases that increase the risk of soft-tissue sarcomas include nevoid basal cell carcinoma syndrome (Gorlin syndrome), Gardner syndrome, tuberous sclerosis, and Werner syndrome.

Etiology and the disease process: Fibrosarcomas begins in the cells that develop fibrous tissues. They start as a lump in these fibrous tissues, usually those that surround the joints in the arms, legs, and torso. The lump is usually painless, but the tumor may grow, pressing against other tissues, such as nerves and muscles, and cause pain. These tumors can spread throughout the body, most commonly to the lungs.

Incidence: Soft-tissue sarcomas are rare, and developing fibrosarcoma is even rarer. Only about 13,000 new cases of soft-tissue sarcoma are diagnosed in the United States annually. This type of cancer is most common in people between the ages of twenty and sixty, with most patients being over fifty. However, it can occur in people of any age, including infants.

Symptoms: This type of cancer is most likely to develop in the arms, legs, or torso. It typically appears as a lump or mass and is not usually painful or swollen. There are generally no other symptoms.

Screening and diagnosis: No screening test is available for fibrosarcoma. The only way to accurately diagnose this type of tumor is with a biopsy, the surgical removal of part of the tumor. The tumor section is then examined under a microscope to determine whether the cells are cancerous. These cells may also be tested for the genetic mutations that are risk factors in this disease to determine the most effective treatment.

Doctors may use a computed tomography (CT) scan or magnetic resonance imaging (MRI) to help diagnose and stage this disease. These tests can help determine the size of the tumor and whether its location will allow for surgical removal. The stages of this disease depend on how abnormal the cells of the tumor appear, the size of the tumor, and how likely the tumor is to spread.

Staging of this disease follows the TNM staging system and histologic grading. These letters represent the size of the primary tumor (T), whether the disease has spread to the lymph nodes (N), the grade of the tumor (G), and whether the tumor has spread or metastasized (M).

The size of the tumor (T) is assigned a number based on the size of the primary tumor as follows:

• T1: Tumor is 5 centimeters or less.
• T1a: Superficial (near the surface) tumor
• T1b: Deep tumor
• T2: Tumor is larger than 5 centimeters.
• T2a: Superficial tumor
• T2b: Deep tumor

Lymph node involvement (N) is assigned a number as follows:

• N0: No evidence of cancer is found in nearby lymph nodes.
• N1: Evidence of cancer is found in nearby lymph nodes.

The grade of the tumor is assigned a number as follows:

• G0: Grade of tumor cannot be assessed.
• G1: The tumor is well defined without reaching into surrounding tissues.
• G2: The tumor has moderately reached into surrounding tissues.
• G3: The tumor has reached well into surrounding tissues.
• G4: The tumor cannot be distinguished from surrounding tissues.

The spread of the disease (M) is divided into two categories:

• M0: No disease is present elsewhere in the body.
• M1: Disease is present in a distant body area.

After the TNGM state of the cancer is determined, a stage is assigned.

• Stage I: Low grade and either superficial or deep (G1 or G2, any T or N, and M at 0)
• Stage II: High grade and either superficial or deep (G3 or G4, any T or N, and M at 0)
• Stage III: High grade, large, and deep (G3 or G4, T2b, N and M at 0)
• Stage IV: Any spread of disease to lymph nodes or other sites (any G, any T, and either N1 or M1)

Treatment and therapy: Treatment for fibrosarcoma usually starts with surgery to remove the tumor and some of the healthy tissue surrounding it. The surgeon must ensure that all edges of the tumor have been removed, and sometimes, this involves removing a large amount of tissue. Sometimes, this may involve amputation of an arm or leg to ensure the entire tumor is removed. However, surgeons often try to use limb-sparing techniques to avoid amputation. Some patients may need reconstructive surgery after the tumor is removed.

Radiation therapy (using high-energy rays to kill the cancerous cells or implanting a tumor with radioactive materials) may also be used with this type of cancer, especially if the cancer’s location makes it difficult to remove the entire tumor or avoid damaging other body parts. Radiation therapy may be used along with surgery to ensure that any cancerous cells that may have been left behind are killed. It may also be used when limb-sparing techniques are used to avoid amputation and ensure any remaining cancer cells are killed.

Chemotherapy (using drugs in the bloodstream to kill cancer cells) may also be used with fibrosarcomas. If the cancer has certain gene mutations, it may be treated with drugs specifically developed to target that mutation. Chemotherapy could also be used before surgery to try to shrink the tumor before removal.

MRIs or CT scans may be used after surgical removal to determine if the entire tumor was removed and to make sure the tumor is not growing back.

Prognosis, prevention, and outcomes: The patient's prognosis depends on their age, the size of the tumor, how deep or superficial the tumor is, and the likelihood of the tumor’s spread at the time of diagnosis.

Patients with soft-tissue sarcomas, such as fibrosarcoma, need to receive follow-up care to ensure no disease recurrence. The overall five-year survival rate is around 65 percent.

Outcomes are generally better for patients under sixty with smaller tumors located in the extremities.

Bibliography

Baker, Laurence H., ed. Soft Tissue Sarcomas. Springer, 2011.

Davis, Donald D., et al. "Fibrosarcoma." National Library of Medicine, 12 Nov. 2023, www.ncbi.nlm.nih.gov/books/NBK560759. Accessed 20 July 2024.

"Fibrosarcoma." Cleveland Clinic, 8 Nov. 2021, my.clevelandclinic.org/health/diseases/22009-fibrosarcoma. Accessed 20 July 2024.

Matsuoka, Masatake, et al. "Comparison of Clinical Features Between Patients with Bone and Soft Tissue Fibrosarcomas." Journal of Surgical Oncology, vol. 126, no. 7, 2022, pp. 1299-1305. doi.org/10.1002/jso.27049.

Sabhavath, M., et al. "Soft Tissue Sarcoma." Kancha, R.K. Biomedical Aspects of Solid Cancers. Springer, 2024, doi.org/10.1007/978-981-97-1802-3‗24.

"Soft Tissue Sarcomas & Subtype." Sarcoma Alliance, sarcomaalliance.org/soft-tissue-sarcomas. Accessed 20 July 2024.

Trent, Jonathan C. Sarcomas: Evidence-Based Diagnosis and Management. Demos Medical Publishing, 2020.

"What Is a Soft Tissue Sarcoma?" American Cancer Society, 23 Nov. 2021, www.cancer.org/cancer/types/soft-tissue-sarcoma/about/soft-tissue-sarcoma.html. Accessed 20 July 2024.