A sarcoma is a rare type of cancer that arises from cells of mesenchymal origin. While there are five types under this category, sarcomas are most frequently contrasted with carcinomas which are much more common. Sarcomas are quite rare, making up about 1% of all adult cancer diagnoses and 15% of childhood cancer diagnoses.

There are many subtypes of sarcoma, which are classified based on the specific tissue and type of cell from which the tumor originates.

The word sarcoma is derived from the Greek 'fleshy excrescence or substance', itself from σάρξ meaning 'flesh'.

Classification

thumb|An illustration showing possible sarcoma locations

Sarcomas are typically divided into two major groups: bone sarcomas and soft-tissue sarcomas, each of which has multiple subtypes. In the United States, the American Joint Committee on Cancer (AJCC) publishes guidelines that classify the subtypes of sarcoma. These subtypes are as follows:

Subtypes of bone sarcoma

  • Osteosarcoma
  • Chondrosarcoma
  • Poorly differentiated round/spindle cell tumors (includes Ewing sarcoma)
  • Hemangioendothelioma
  • Angiosarcoma
  • Fibrosarcoma/myofibrosarcoma
  • Chordoma
  • Adamantinoma
  • Other:
  • Liposarcoma
  • Leiomyosarcoma
  • Malignant peripheral nerve sheath tumor
  • Rhabdomyosarcoma
  • Synovial sarcoma
  • Malignant solitary fibrous tumor. but several factors are associated with an increased risk of developing bone sarcoma. Previous exposure to ionizing radiation (such as prior radiation therapy) is one such risk factor. Exposure to alkylating agents, such as those found in certain cancer chemotherapeutic medicines, also increases the risk of bone sarcoma. Importantly, however, none of these laboratory findings are specific to bone sarcomas, meaning that elevations in these lab values are associated with many other conditions as well as sarcoma, and thus cannot be relied upon to conclusively diagnose sarcoma.

Staging

In general, cancer staging refers to how advanced a cancer is, and usually it is based upon factors such as tumor size and whether it has spread to other parts of the body. Staging is important because the stage affects the prognosis (likely outcome), as well as the types of treatments that are likely to be effective against the cancer. In general, grade refers to how aggressive the cancer is and how likely it is to spread to other parts of the body ("metastasize"). Since high-grade tumors are more likely to undergo metastasis (invasion and spread to locoregional and distant sites), they are treated more aggressively. The recognition that many sarcomas are sensitive to chemotherapy has dramatically improved the survival of patients. For example, in the era before chemotherapy, long-term survival for pediatric patients with localized osteosarcoma was only about 20%, but now has risen to 60–70%.

Screening

In the US, the US Preventive Services Task Force (USPSTF) publishes guidelines recommending preventive screening for certain types of common cancers and other diseases. , the USPSTF does not recommend screening for sarcoma, Like the USPSTF, ACS does not recommend preventive screening for sarcoma. Limb-sparing surgery, as opposed to amputation, can now be used to save the limbs of patients in at least 90% of extremity (arm or leg) sarcoma cases. Treatment can be a long and arduous process, lasting about a year for many patients.

  • Pediatric rhabdomyosarcoma is usually treated with chemotherapy, surgery, and sometimes radiotherapy. Pediatric rhabdomyosarcoma patients have a 50–85% long term survival rate.
  • Osteosarcoma is a cancer of the bone that is treated with surgical resection of as much of the cancer as possible, often along with chemotherapy. Radiotherapy is a second alternative to surgery, although not as successful.

It was believed that higher doses of chemotherapy might improve survival. found only one RCT and this did not favour either of the two treatment arms with respect to overall survival. As a result, high dose chemotherapy with stem cell rescue is generally considered appropriate only in the research setting.

Prognosis

Factors that affect prognosis

The AJCC has identified several factors that affect prognosis of bone sarcomas: The American Cancer Society (ACS) estimates that 2,140 people in the US will die in 2023 from bone sarcomas, accounting for 0.3% of all cancer deaths. The median age at death is 61 years old, although death can occur in any age group. Thus, the 5-year survival is 80.8% for soft-tissue sarcomas that have not spread beyond the primary tumor ("localized" tumors), 58.0% for soft-tissue sarcomas that have spread only to nearby lymph nodes, and 16.4% for soft-tissue sarcomas that have spread to distant organs. Some sarcomas, such as leiomyosarcoma, chondrosarcoma, and gastrointestinal stromal tumor (GIST), are more common in adults than in children.

Research

Treatment of sarcoma, especially when the sarcoma has spread, or "metastasized", often requires chemotherapy. However, existing chemotherapeutic medicines are associated with significant toxicities and are not highly effective in killing cancer cells. These drugs are not yet FDA- or other regulator-approved treatment, except PDL1 inhibitor atezolizumab for the ultra-rate diagnosis of alveolar soft part sarcoma. Other strategies, such as small-molecule targeted therapy, biologic agents (e.g., small interfering RNA molecules), and nanoparticle-directed therapy, also are under active investigated.

Research by Clinician Scientist of University of British Columbia Torsten O. Nielsen has contributed to advances in the molecular understanding and classification of sarcoma, particularly soft tissue subtypes. His work has emphasized the use of gene expression profiling and genomic analysis to improve diagnostic accuracy and distinguish between histologically similar tumors, including synovial sarcoma and other spindle cell neoplasms.

Nielsen's studies have also examined the role of characteristic fusion oncogenes, such as SS18–SSX in synovial sarcoma, and their effects on gene regulation and tumor development. This research has helped clarify the biological mechanisms underlying sarcoma progression and supported the development of molecularly defined disease categories.

Awareness

In the US, July is widely recognized as Sarcoma Awareness Month. The UK has a Sarcoma Awareness Week in July led by Sarcoma UK, the bone and soft-tissue cancer charity.

American YouTuber Technoblade was diagnosed with sarcoma in August 2021, and died from his illness in June 2022 after the sarcoma metastasized. He had raised over $500,000 in a charity stream. Many YouTubers have raised awareness and donated to charities such as the Sarcoma Foundation of America after Technoblade's diagnosis and passing. To date, Technoblade's fans have raised over $1,000,000 for sarcoma research.

TikTok has provided a voice for many creators to chronicle their experiences with sarcoma. "Dance You Outta My Head", by American singer Cat Janice, went viral on TikTok in early 2024 before the singer died of sarcoma, prompting awareness of this rare disease.

Kimberley Nix, a Canadian physician, chronicled her journey with undifferentiated pleomorphic sarcoma, from her diagnosis to eventual death, on TikTok under the username @cancerpatientmd. Nix died on 8 May 2024 at the age of 31, and her death was announced in a video uploaded posthumously to her TikTok page. In many of her videos, she links viewers to her Own.Cancer fundraiser, which has raised almost C$118,000 as of 17 May 2024.

References

  • Bone sarcoma at the National Cancer Institute
  • What is Sarcoma?
  • Sarcoma Help from the Liddy Shriver Sarcoma Initiative