Radiation-induced sarcoma

Radiation-induced sarcoma (RIS) can originate in either the irradiated bone or soft tissues after a period of latency. They are usually high-grade tumors with a poor prognosis when compared with primary sarcomas. Malignant fibrous histiocytoma and osteosarcoma are the two most common histological types. 

The incidence is not well known as it is related theoretically to all radiation therapy procedures 1. One study in Finland taking in consideration all treated parts of the body found a risk of 0.05% 2. RIS constitutes ~4% of all sarcomas 3.

It was found a higher risk of RIS among younger patients; it has been thought a link between a particular cancer type that  is more common among the young 2. There is a direct correlation with the risk and the radiation doses 4.

A history of prior radiation therapy is mandatory for a diagnosis of RIS to be made. The median latency period is around 14 years 4, however RIS can develop in a short time as 3-4 years following radiotherapy. 

Malignant fibrous histiocytoma and osteosarcoma are the two most common histological types, although other histologies (e.g. angiosarcoma and rhabdomyosarcoma) can occur. 

RIS has a poor prognosis compared to primary sarcomas: the 5-year survival rates vary from 17 to 58% in RIS compared with 54–76% in patients with sporadic sarcomas. Some unfavourable factors related to RIS are: central tumor site, incomplete surgical remission, microscopic tumor necrosis and the presence of metastases, the two former factors overrepresented in RIS 3.

Similar to primary sarcomas, RIS originating soft-tissues has on tumor size and grade the two most important prognostic factors 1:

  • high-grade tumors larger than 5 cm: usually treated with primary chemotherapy followed by a margin-negative surgical excision of the residual disease 
  • low-grade tumors and high-grade tumors with 5 cm or smaller: usually treated with a margin-negative surgical excision and systemic chemotherapy is considered when a negative margin is not certain

RIS originating in bone is usually approached with primary chemotherapy followed by a margin-negative excision 1

RIS was first described in 1920’s in workers painting radium watch dials 4.

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Article information

rID: 36661
Tag: cases
Synonyms or Alternate Spellings:
  • Radiation-induced sarcomas
  • Radioinduced sarcoma

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