Background

Uterine sarcomas are uncommon gynaecological cancers. They are a small but important group of tumours because their management may require a different approach compared to some of the more common cancers of the female genital tract. Due to small numbers, there is limited evidence to guide treatments. From the patient's perspective having a rarer type of cancer may feel more challenging to cope with for several reasons, for example, they may feel more isolated; it might take longer to make a diagnosis; and it can be more difficult for them to find information about their type of tumour.

Sarcomas can occur anywhere within the female genital tract, but the most common site is the uterus. These tumours account for <1% of all gynaecological cancers. They usually behave aggressively and are associated with a poor prognosis.

Terminology and Pathology

The accurate histological assessment of uncommon gynaecological tumours requires expert review by specialist pathologists at cancer centres. A correct pathological diagnosis is essential for planning appropriate management.

The terminology of uncommon cancers can be confusing, as their nomenclature has evolved with improvements in understanding of the pathology. All cancers are classified by both the primary location of tumour (primary site) and the cell type from which the cancer originates (histological type). Carcinomas are malignant cells that arise from epithelial cells and account for the majority of gynaecological cancers. In contrast, sarcomas are malignant cells that arise from mesenchymal tissues such as smooth muscle, connective tissue, fibrous tissue, fat and endothelial cells. In addition to identifying the underlying cell type of the tumour, it is also important to grade the tumour, usually as low (G1, well differentiated) or high (G3, poorly differentiated). Grading is generally based on the degree of cellular abnormality, the presence of necrosis and the rate of cellular proliferation (the mitotic index, measured by the number of mitotic figures identified within a given magnification field). Tumour grading helps to predict how the tumour is likely to behave and respond to treatment.

Carcinosarcoma is a term used to describe a tumour that contains a mixture of both malignant epithelial and mesenchymal cell types. These were previously referred to as malignant mixed Mullerian tumours (MMMTs).