Sarcoma of unknown primary: myth or reality?

Area of Science:

• Oncology
• Pathology
• Medical Research

Background:

• Sarcoma of unknown primary (SUP) is diagnosed when metastatic sarcoma lacks an identifiable primary site.
• The concept of SUP as a distinct entity is debated due to sarcomas' potential to arise from various tissues.
• This review critically examines the validity of SUP as a separate diagnostic category.

Purpose of the Study:

• To evaluate the validity of Sarcoma of Unknown Primary (SUP) as a distinct clinical entity.
• To compare the clinical features and outcomes of SUP with sarcomas of known primary sites.

Main Methods:

• A comprehensive literature search of Medline/PubMed and Google Scholar (1990-April 2020) was conducted.
• English-language publications reporting on SUP were included, excluding specific sarcoma types.
• Kaplan-Meier method was used for overall survival analysis.

Main Results:

• Twenty-six patients with SUP were identified, with a median age of 17.5 years.
• Rhabdomyosarcoma subtypes were most common; nearly two-thirds had multiple metastatic sites.
• Median overall survival for 13 patients with data was 10.0 months.

Conclusions:

• SUP exhibits similar aggressive clinical behavior, poor chemotherapy response, and dismal outcomes as sarcomas of known primary sites.
• SUP does not appear to possess unique natural history or biological properties to be considered a distinct entity.
• Autopsy findings in two cases identified primary tumors in the chest wall and paravertebral regions.