Norwegian Sarcoma Registry

Summary from the annual report 2025

Sarcoma is a collective term for rare mesenchymal malignant tumors that arise in the body’s connective and supporting tissues, such as muscle, adipose tissue, connective tissue, and bone. In 2025, 612 patients were diagnosed with sarcoma in Norway. Sarcomas can occur in all parts of the body and comprise numerous subtypes with substantial variation in aggressiveness, treatment, and prognosis.

Approximately nine out of ten cases are soft tissue sarcomas, while the remainder are bone sarcomas. Soft tissue sarcomas occur mainly in adults and the elderly and may arise both superficially and deep within the body, for example in the extremities, trunk, or internal organs. Many of these tumors have an indolent course, but some subtypes are aggressive.

Bone sarcomas are rarer and more often affect children and young adults. They are generally higher-grade malignancies andrequire rapid, structured diagnostic evaluation and multimodal treatment at specialized centers.

An important subgroup of soft tissue sarcoma consists of abdominal and retroperitoneal sarcomas. In 2025, more than 200such cases were registered, with gastrointestinal stromal tumors (GIST) accounting for the majority. These tumors may grow for a long time without causing clear symptoms and are often detected late or as incidental findings. Appropriate referral prior to biopsy or surgery is particularly critical in this group, and the report shows that most patients are referred in accordance with national recommendations. 

Previous radiotherapy is a known risk factor, and approximately 2–3 % of sarcoma cases are considered radiationinduced. About one in four patients has had a previous cancerdiagnosis. Genetic predisposition may also contribute to an increased risk of multiple cancers in the same individual. 

The diagnostic workup of sarcoma usually begins with imaging. A large number of examinations are reviewed at sarcoma centers to distinguish benign conditions from tumors requiring further evaluation. When sarcoma is suspected, patients are usually referred to a sarcoma center prior to biopsy. The report shows high target achievement for several key quality indicators, including the use of MRI for deep soft tissue tumors and PET-CT for osteosarcoma and Ewing sarcoma.

Surgery is themain stay of treatment for most sarcoma diagnoses, often combined with radiotherapy and, in selected cases, systemic anticancer therapy. The use of chemotherapy in elderly patients and during the final phase of life is low, indicating a deliberate emphasis on quality of life when cure is not achievable. 

The 2025 annual report also includes new areas, such as analyses of sarcomas of the breast and chest wall, as well as data on benign notifiable diagnoses including giant cell tumor of bone and desmoid fibromatosis. In addition, proton therapy became available in Norway in 2025, and the first sarcoma patients received this treatment during the year. Two proton therapy centers, in Bergen and Oslo, were opened in 2025. 

Overall, the report shows that the diagnostic evaluation and treatment of sarcoma in Norway largely adhere to professional guidelines and are of good quality. At the same time, the report highlights the need for continued efforts to improve reporting to the clinical registry and to monitor developments in treatment practices and regional variations over time.